Methods for fabrication of dual network polymers formed from polymeric precursors and in SITU polymerization and systems for same

Abstract

Aspects of the present disclosure include methods for making a conductive pyrolytic carbon microstructure. Methods according to certain embodiments include irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition having a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface, displacing the build elevator away from the build surface, irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second non-polymerized region in contact with the build surface, repeating this in a manner sufficient to generate a polymeric microstructure, contacting the polymeric microstructure with a carbon precursor component (e.g., incorporating a carbon precursor component into the polymeric microstructure) and pyrolyzing the polymeric microstructure to generate a conductive pyrolytic carbon microstructure with a conductive component positioned therein. In some instances, the pyrolytic carbon microstructure is an interpenetrating network that forms a homogeneous pyrolytic carbon material. Conductive pyrolytic carbon microstructures having a conductive component positioned within prepared by the subject methods are also disclosed. Microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate) are also provided.

Description

[0001] METHODS FOR FABRICATION OF DUAL NETWORK POLYMERS FORMED FROM POLYMERIC PRECURSORS AND IN SITU POLYMERIZATION AND SYSTEMS FOR SAME

[0002] GOVERMENT RIGHTS

[0003] This invention was made with Government support under contract 2146755 awarded by the National Science Foundation and under contract NNH18ZHA008CMIROG6R awarded by the National Aeronautics and Space Administration. The Government has certain rights in the invention.

[0004] CROSS-REFERENCE TO RELATED APPLICATION

[0005] Pursuant to 35 U.S.C. § 119(e), this application claims the benefit of priority to the filing date of United States Provisional Patent Application Serial No. 63 / 619,685, filed on January 10, 2024 and United States Provisional Patent Application Serial No. 63 / 558,305, filed on February 27, 2024; the disclosures of which applications are incorporated herein by reference.

[0006] INTRODUCTION

[0007] Additive manufacturing techniques for printing polymeric resins have been used in applications such as personalized human protection, wearable electronics, and functionally graded materials. Printed materials have been shown to have desirable mechanical, electrical, and chemically stable properties. Continuous liquid interface production (CLIP), like other digital light projection (DLP) methods, projects a rapid sequence of ultraviolet patterns (UV) to photopolymerize a resin layer-by-layer. Unlike other DLP methods which require layer by layer delamination between each exposure, CLIP generates a polymer structure by resin renewal underneath the build surface through a continuous liquid interface, the dead zone, created by oxygen, a polymerization inhibitor, fed through the highly oxygen permeable window at the bottom of the resin reservoir. The combination of improved optical projection and CLIP technology has allowed printers to reach sub-micron lateral (XY) resolution at speeds 100 times faster than other 3D printing methods. SUMMARY

[0008] Aspects of the present disclosure include methods for making conductive pyrolytic carbon microstructures. Methods according to certain embodiments include irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition having a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface, displacing the build elevator away from the build surface, irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second nonpolymerized region in contact with the build surface, repeating this in a manner sufficient to generate a polymeric microstructure, contacting the polymeric microstructure with a carbon precursor component (e.g., incorporating a carbon precursor component into the polymeric microstructure) and pyrolyzing the polymeric microstructure to generate a conductive pyrolytic carbon microstructure with a conductive component positioned therein. In some instances, the pyrolytic carbon microstructure is an interpenetrating network that forms a homogeneous pyrolytic carbon material. Conductive pyrolytic carbon microstructures having a conductive component positioned within prepared by the subject methods are also disclosed. Microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate) are also provided.

[0009] In some embodiments, the methods include fabricating hierarchical 3-D polymer structures with high pyrolysis char yields formed by additive manufacturing followed by in situ polymerization of interpenetrating networks and infusion of carbon precursor additives. In some instances, the methods include fabricating dual networks with high pyrolysis carbon yields via infusion of gels with monomers and subsequent in situ polymerization. In some instances, the methods include holistic manufacturing of 3-D architected electrodes for high volumetric electrochemical reactions for energy sustainability. Carbon materials formed by pyrolysis of 3D printed polymers have many potential applications in sustainable manufacturing from renewable energy storage to carbon capture to electrification. Pyrolysis requires high surface area to volume structures to avoid mechanical integrity concerns due to thinner features better facilitate volatiles escaping during heating without deformation. However, traditional molding methods are not able to fabricate large objects with thin features, such as beam-based lattice structures, that achieve the desired high surface area to volume ratio characteristic. In some instances, the methods of the present disclosure include a holistic manufacturing process for the fabrication of 3D carbon-based structures that will empower high-volumetric capacities and rapid occurrence electrochemical reactions. This innovative approach combines CLIP 3D printing of polymeric structures followed by infusion of high char yield polymers (e.g., polyacrylonitrile and carbohydrates among others) as well as metal catalyst-assisted graphitization and nanocarbon growth during pyrolysis. The resulting highly electrically conductive 3D carbon hierarchical structures offer high surface areas with low tortuosity.

[0010] In some embodiments, the carbon precursor component includes one or more metals. In some instances, the carbon precursor component includes a reactive precursor. In some instances, the carbon precursor component includes a carbohydrate such as sucrose, fructose, ribose, glucose, xylose, starch, etc., and the carbohydrate is simultaneously infused and carbonized in the polymeric microstructure via a solvothermal process. In some instances, the swelling takes place in an aqueous solution prior to the solvothermal carbonization process. In some instances, the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to react carbonaceous solvothermal derivatives with vinyl groups positioned on the polymeric microstructure, e.g., via a Diels-Alder cycloaddition reaction. In some instances, the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to generate one or more aromatic moieties on the polymeric microstructure e.g., via a Diels-Alder cycloaddition reaction. In some embodiments, pyrolyzing the polymeric microstructure generates a conductive pyrolytic carbon microstructure metal composite. In some instances, the method includes contacting the conductive pyrolytic carbon microstructure with carbon nanotubes, carbon nanofibers or a combination thereof. In some instances, a layer of carbon nanotubes, carbon nanofibers or combination thereof is formed on a surface of the pyrolytic carbon microstructure. In some instances, methods include contacting the conductive pyrolytic carbon microstructure with an active material. In certain instances, the active material is electrografted to the conductive pyrolytic carbon microstructure. In certain instances, the active material is electro-grafted to the layer of carbon nanotubes, carbon nanofibers or combination thereof on the surface of the pyrolytic carbon microstructure. In some instances, electro-grafting of the active material to the conductive pyrolytic carbon microstructure is sufficient to generate a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0011] In some embodiments, the carbon precursor component is a polymeric precursor. In some embodiments, the polymeric precursor is an acrylonitrile. In some instances, the non-conductive polymer formed by polymerization (e.g., in situ within the polymeric microstructure) is a polyacrylonitrile. In some instances, pyrolysis of the polymeric microstructure with the non-conductive polymer positioned within forms a conductive pyrolytic carbon lattice from the non-conductive polymer, such as a conductive pyrolytic carbon 3D lattice. In some instances, carbonization of the non- conductive polymer forms a stabilized polymer such as by cyclization stabilization of a polyacrylonitrile polymer. In certain instances, carbonization forms a 3D lattice of cyclized conductive polymer (e.g., 3D lattice formed by cyclization of polyacrylonitrile).

[0012] In some embodiments, the polymeric precursor is contacted with the polymeric microstructure. In some instances, contacting the polymeric precursor is sufficient to incorporate the polymeric precursor within the internal cavities of the polymeric microstructure. In some instances, contacting the polymeric precursor with the polymeric microstructure includes swelling the polymeric microstructure with the polymeric precursor. In some instances, the polymeric precursor is swelled into the polymeric microstructure with a solvent, such as with dimethyl sulfoxide (DMSO). In certain instances, the polymeric precursor is combined into a composition that includes a solvent (e.g., DMSO) and a radical initiator (e.g., a thermal initiator or a photo-initiator) such as azobisisobutyronitrile (AIBN)). In certain instances, the polymeric precursor is combined in a composition that includes a crosslinker (e.g. polyethylene glycol) diacrylate).

[0013] In embodiments, the polymeric precursor is polymerized in situ within the polymeric microstructure. In some instances, polymerizing the polymeric precursor includes applying heat to the polymeric microstructure with the polymeric precursor (e.g., swelled polymeric microstructure). In some instances, the polymer microstructure with the polymeric precursor within is heated to a temperature of from 50 °C to 100 °C, such as from 60 °C to 80 °C. In some instances, the polymer microstructure with the polymeric precursor within is heated in the presence of a heating medium, such as one or more of mineral oil, dimethyl sulfoxide (DMSO), argon gas and a fluorinated heattransfer fluid.

[0014] In some instances, the non-conductive polymer within the polymeric microstructure is prepared for pyrolysis through an oxidative thermal treatment of the polymeric microstructure with the non-conductive polymer positioned within. In some instances, oxidative treatment includes applying heat to the polymeric microstructure with the non-conductive polymer in the presence of oxygen. In some instances, oxidative treatment includes heating to a temperature of from 150 °C to 350 °C, such as from 200 °C to 300 °C in the presence of oxygen. In some instances, the temperature is ramped at a rate of 0.01 °C / minute or more, such as by 0.05 °C / minute or more, such as by 0.1 °C / minute or more, such as by 0.5 °C / minute or more, such as by 1 °C / minute or more, such as by 2 °C / minute or more, such as by 3 °C / minute or more, such as by

[0015] 4 °C / minute or more, such as by 5 °C / minute or more, such as by 6 °C / minute or more, such as by 7 °C / minute or more, such as by 8 °C / minute or more, such as by

[0016] 9 °C / minute or more and including by 10 °C / minute or more. In some instances, the temperature is ramped at a rate of from 0.1 °C / minute to 10 °C / minute, such as from 3 °C / minute to 9 °C / minute, such as from 4 °C / minute to 8 °C / minute and including

[0017] 5 °C / minute. The oxidative treatment may be applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of 20 minutes or more, such as 30 minutes or more, such as 60 minutes or more, such as 90 minutes or more, such as 120 minutes or more and including 180 minutes or more. In some instances, the oxidative treatment is applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of from 20 minutes to 120 minutes, such as from 30 minutes to 90 minutes and including oxidative treatment for about 60 minutes.

[0018] In certain embodiments, methods include an isothermal hold after the oxidative treatment of the polymeric microstructure with non-conductive polymer positioned within. In some instances, the isothermal hold includes maintaining the polymeric microstructure with non-conductive polymer positioned within at a temperature from 300 °C to 450 °C, such as from 325 °C to 425 °C under an inert atmosphere, such as under nitrogen (N2) gas. The isothermal hold may be applied for a duration of 20 minutes or more, such as 30 minutes or more, such as 60 minutes or more, such as 90 minutes or more, such as 120 minutes or more and including 180 minutes or more. In some instances, the isothermal hold is applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of from 20 minutes to 120 minutes, such as from 30 minutes to 90 minutes and including an isothermal hold for about 60 minutes.

[0019] In embodiments, the polymeric microstructure with non-conductive polymer positioned within is pyrolyzed by heating in a manner sufficient to carbonize the polymeric microstructure with non-conductive polymer into a pyrolytic carbon microstructure with a conductive pyrolytic carbon polymer positioned therein. In some instances, the pyrolytic carbon microstructure is formed from monolithic hard carbon. In some instances, the polymeric microstructure with non-conductive polymer is pyrolyzed by heating under an inert atmosphere. In some instances, the polymeric microstructure with non-conductive polymer is pyrolyzed by heating under vacuum. In other instances, the polymeric microstructure with non-conductive polymer is pyrolyzed by heating under an inert gas selected from nitrogen, argon and helium. In some embodiments, the polymeric microstructure with non-conductive polymer positioned within is heated to a temperature of 300 °C or more, such as 400 °C or more, such as 500 °C or more, such as 600°C or more, such as 700 °C or more, such as 800 °C or more, such as 900 °C or more, such as 1000 °C or more, such as 1100 °C or more, such as 1200 °C or more, such as 1300 °C or more, such as 1400 °C or more, such as 1500 °C or more and including 1600 °C or more. In some instances, pyrolysis includes heating to a temperature of from 300 °C to 1600 °C, such as from 400 °C to 1000 °C. In some instances, the temperature is ramped at a rate of 0.01 °C / minute or more, such as by 0.05 °C / minute or more, such as by 0.1 °C / minute or more, such as by 0.5 °C / minute or more, such as by 1 °C / minute or more, such as by 2 °C / minute or more, such as by 3 °C / minute or more, such as by 4 °C / minute or more, such as by 5 °C / minute or more, such as by 6 °C / minute or more, such as by 7 °C / minute or more, such as by

[0020] 8 °C / minute or more, such as by 9 °C / minute or more and including by 10 °C / minute or more. In some instances, the temperature is ramped at a rate of from 0.1 °C / minute to 10 °C / minute, such as from 3 °C / minute to 9 °C / minute, such as from 4 °C / minute to 8 °C / minute and including 5 °C / minute.

[0021] In certain embodiments, pyrolysis methods include an isothermal hold after the oxidative treatment of the polymeric microstructure with non-conductive polymer positioned within and before heating to the final upper pyrolysis temperature. In some instances, the isothermal hold includes maintaining the polymeric microstructure with non-conductive polymer positioned within at a temperature from 300 °C to 450 °C, such as from 325 °C to 425 °C under an inert atmosphere, such as under nitrogen (N2) gas. The isothermal hold may be applied for a duration of 20 minutes or more, such as 30 minutes or more, such as 60 minutes or more, such as 90 minutes or more, such as 120 minutes or more and including 180 minutes or more. In some instances, the isothermal hold is applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of from 20 minutes to 120 minutes, such as from 30 minutes to 90 minutes and including an isothermal hold for about 60 minutes.

[0022] Pyrolysis may, in some instances, be for a duration of 1 hour or more, such as for 2 hours or more, such as for 3 hours or more, such as for 4 hours or more, such as for 5 hours or more and including for 6 hours or more. In some embodiments, the polymeric microstructure is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 50% or less. In some instances, the polymeric microstructure is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 25% or less. In some instances, the polymeric microstructure is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 5% or more, such as by 10% or more, such as by 15% or more, such as by 20% or more and including by 25% or more. In some embodiments, the pyrolytic carbon microstructure has an electrical conductivity that is 50% or greater as compared to the electrical conductivity of the polymeric microstructure, such as determined by a quantitative conductivity test or impedance determination, such as 75% or greater, such as 100% or greater, such as 2- fold or greater, such as 3-fold or greater, such as 5-fold or greater and including where the pyrolytic carbon microstructure has an electrical conductivity that is 10-fold or greater as compared to the electrical conductivity of the polymeric microstructure. In some instances, the pyrolytic carbon microstructure exhibits a compressive strength that is 50% or greater as compared to the compressive strength of the polymeric microstructure. In some instances, the pyrolytic carbon microstructure exhibits a compressive strength that is 0.001 GPa or greater, such as 0.005 GPa or greater, such as 0.01 GPa or greater, such as 0.05 GPa or greater, such as 0.1 GPa or greater, such as 0.5 GPa or greater, such as 1 GPa or greater, such as 10 GPa or greater. In certain instances, the pyrolytic carbon microstructure exhibits a compressive strength that is 13 GPa or greater. In some instances, pyrolyzing the polymeric microstructure comprising the non-conductive polymer exhibits a char yield of 40% or more, such as 60% or more.

[0023] In some embodiments, in preparing the pyrolytic carbon microstructure, the polymerizable composition contains a polymerizable material selected from the group consisting of polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, aliphatic urethane acrylate, polyacrylonitrile, polycaprolactone, polyglycolic acid, polylactic acid, polystyrene, divinylbenzene, polylactic-co-glycolic acid, polyethylene glycol, thiol-enes, anhydrides, polyacrylic acid, poly methylmethacrylate, polyvinyl alcohol, polyvinylpyrrolidone, poly(diaminonaphthalene), vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof. In certain instances, the polymerizable composition includes polyethylene glycol) diacrylate (PEGDA).

[0024] In some embodiments, the polymerizable composition is in contact with the build elevator and the build surface. In some instances, the method includes irradiating the polymerizable composition for a duration sufficient to bond the first polymerized region of the polymerizable composition to the build elevator. In some instances, the build elevator is displaced in predetermined increments of from 0.5 pm to 10.0 pm. In some instances, the method further includes adding polymerizable composition to the build surface after each displacement of the build elevator away from the build surface. In some embodiments, the polymerizable composition is irradiated through the build surface. In some instances, the polymerizable composition is irradiated in the presence of a polymerization inhibitor. In some instances, the polymerizable composition is continuously polymerized while displacing the build elevator away from the build surface. In some instances, the build surface is permeable to the polymerization inhibitor, such as where the polymerization inhibitor is oxygen.

[0025] In some instances, the pyrolytic carbon microstructure is an interpenetrating network that forms a homogeneous pyrolytic carbon material. In some embodiments, the pyrolytic carbon microstructure has a lattice microstructure. In some instances, the pyrolytic carbon microstructure has 2 or more repeating lattice cell units. In some instances, the pyrolytic carbon microstructure has a gradient in the lattice cell units such that the density of lattice cell units increases across a longitudinal axis of the pyrolytic carbon microstructure. In some embodiments, the lattice cell unit has a lattice shape selected from tetrahedral, Kagome, rhombic, icosahedral, Voronoi, octet, and triangular. In some instances, the pyrolytic carbon microstructure has lattice cell units having a size of from 25 pm to 1000 pm. In some embodiments, the lattice microstructure has a plurality of struts. In some instances, the lattice microstructure has struts having a thickness of from 5 pm to 150 pm. In some instances, the pyrolytic carbon microstructure has a volume of from 0.01 pL to 2 pL.

[0026] Aspects of the present disclosure also include a conductive pyrolytic carbon microstructure, such as a conductive microstructure having one or more conductive components positioned therein. In some instances, the pyrolytic carbon microstructure includes one or more metals. In some instances, the conductive pyrolytic carbon components positioned therein includes hydrochar derived from the solvothermal decomposition of a carbohydrate such as sucrose, fructose, ribose, glucose, xylose, starch, etc., reacted with one or more vinyl groups, e.g., via a Diels-Alder cycloaddition reaction positioned on the polymeric microstructure. In some instances, the conductive pyrolytic carbon microstructure includes carbon nanotubes, carbon nanofibers or a combination thereof. In some instances, the carbon nanotubes, carbon nanofibers or a combination thereof form a layer on a surface of the conductive pyrolytic carbon microstructure. In some instances, a layer of carbon nanotubes, carbon nanofibers, or a combination thereof is grown on the surface of the pyrolytic carbon microstructure. In some instances, the CNTs / CNFs are grown from an externally supplied hydrocarbon gas, such as ethylene, at the surface of a metal catalyst deposited prior to pyrolysis. In some instances, the hydrocarbon byproducts generated during the decomposition of the polymer form a small amount of CNTs / CNFs. In some instances, the catalyst species are reduced by a reducing gas, such as H2or carbon during the pyrolysis by carbothermal reduction. The catalyst may be deposited on the polymer template prior to pyrolysis, or after pyrolysis.

[0027] In certain embodiments, the conductive pyrolytic carbon microstructure includes an active material. In some instances, the active material is electro -grafted to the conductive pyrolytic carbon microstructure. In certain instances, the active material forms a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0028] In some embodiments, the conductive pyrolytic carbon microstructure includes a conductive pyrolytic carbon polymer positioned within the pyrolytic carbon microstructure. In some instances, when pyrolyzed together, the material is an interpenetrating network of polymers and additives pyrolyzed together that form a homogeneous pyrolytic carbon material. In some instances, the conductive pyrolytic carbon polymer includes a conductive pyrolytic carbon lattice, such as a 3D lattice. In some instances, the non-conductive polymer is a polyacrylonitrile. In some instances, the pyrolytic carbon microstructure is monolithic hard carbon. In some instances, the pyrolytic carbon microstructure exhibits a compressive strength that is 0.001 GPa or greater, such as 0.005 GPa or greater, such as 0.01 GPa or greater, such as 0.05 GPa or greater, such as 0.1 GPa or greater, such as 0.5 GPa or greater, such as 1 GPa or greater, such as 10 GPa or greater. In some instances, the pyrolytic carbon microstructure is electrically conductive. In some instances, the pyrolytic carbon microstructure has a lattice microstructure. In some instances, the pyrolytic carbon microstructure has 2 or more repeating lattice cell units. In some instances, the pyrolytic carbon microstructure has a gradient in the lattice cell units such that the density of lattice cell units increases across a longitudinal axis of the pyrolytic carbon microstructure. In some instances, the lattice cell unit has a lattice shape selected from the group consisting of tetrahedral, Kagome, rhombic, icosahedral, Voronoi, octet, and triangular. In some instances, the pyrolytic carbon microstructure has lattice cell units having a size of from 25 pm to 1000 pm. In some instances, the lattice microstructure comprises a plurality of struts. In some instances, the lattice microstructure comprises struts having a thickness of from 5 pm to 150 pm. In some instances, the pyrolytic carbon microstructure has a volume of from 0.01 pL to 2 pL. In some instances, the pyrolytic carbon microstructure has a pyrolyzed polymeric microstructure.

[0029] In some embodiments, the pyrolytic carbon microstructure having a conductive pyrolytic carbon polymer positioned therein is formed from pyrolysis of a polymeric microstructure formed from polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, urethane acrylate, polycaprolactone, polyglycolic acid, polylactic acid, polylactic-co-glycolic acid, polyethylene glycol, thiol-enes, anhydrides, polyacrylic acid, polyacrylonitrile, poly methylmethacrylate, polystyrene, divinylbenzene, ethoxylated pentaerythritol tetraacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyhexanediol diacrylate, polyvinyl alcohol, polyvinylpyrrolidone, poly(diaminonaphthalene), vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof and non-conductive polymer formed from polymerization (and in some instances, oxidative treatment) of polyacrylonitrile.

[0030] Aspects of the present disclosure also include microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate). In some instances, the microelectrode includes a substrate. In certain instances, the substrate is planar. In certain instances, the substrate is non-planar. In some instances, the substrate is conductive, such as a substrate formed from a metal. In some instances, the substrate is non-conductive, such as where the substrate is an insulator. BRIEF DESCRIPTION OF THE FIGURES

[0031] The disclosure may be best understood from the following detailed description when read in conjunction with the accompanying drawings. Included in the drawings are the following figures:

[0032] FIG. 1 depicts the pyrolysis of a polymeric microstructure to a conductive pyrolytic carbon microstructure according to certain embodiments.

[0033] FIG. 2 depicts a microelectrode having a high surface area conductive pyrolytic carbon microstructure according to certain embodiments.

[0034] FIG. 3 depicts a printed susceptor having a conductive pyrolytic carbon microstructure according to certain embodiments.

[0035] FIG. 4 depicts steps for generating a conductive pyrolytic carbon microstructure having incorporated active material according to certain embodiments.

[0036] FIG. 5 depicts hierarchal three-dimensional structure of a conductive pyrolytic carbon microstructure according to certain embodiments.

[0037] FIG. 6 depicts a comparison of strut diameter before and after solvothermal process according to certain embodiments.

[0038] FIG. 7 depicts a comparison of physical characteristics of lattice structures of polyethylene glycol) diacrylate (PEGDA) after different durations and conditions for solvothermal carbonization according to certain embodiments.

[0039] FIG. 8 depicts pyrolysis shrinkage behavior of different lattice unit cell geometries of polymeric microstructures according to certain embodiments.

[0040] FIG. 9 depicts generating pyrolyzed polyacrylonitrile (PAN) three-dimensional lattices according to certain embodiments.

[0041] FIG. 10 depicts polyacrylonitrile (PAN) gel infusion in a polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments.

[0042] FIG. 11 depicts the changes in physical characteristics of polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold during the polymerization and pyrolysis process according to certain embodiments.

[0043] FIG. 12 depicts a comparison of pyrolyzed poly(ethylene glycol) diacrylate (PEGDA) scaffolds and pyrolyzed polyacrylonitrile (PAN) gel infused poly(ethylene glycol) diacrylate (PEGDA) scaffolds according to certain embodiments. FIG. 13 depicts attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy of a polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments.

[0044] FIG. 14 depicts thermogravimetric analysis of polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate char yields from pyrolysis after oxidative isothermal holds according to certain embodiments.

[0045] FIG. 15 depicts surface morphology of a pyrolyzed polyacrylonitrile (PAN) gel infused poly(ethylene glycol) diacrylate (PEGDA) scaffold by scanning electron microscopy according to certain embodiments.

[0046] FIG. 16 depicts cyclic voltammetry for a pyrolyzed polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments.

[0047] DETAILED DESCRIPTION

[0048] Aspects of the present disclosure include methods for making a conductive pyrolytic carbon microstructure. Methods according to certain embodiments include irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition having a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface, displacing the build elevator away from the build surface, irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second nonpolymerized region in contact with the build surface, repeating this in a manner sufficient to generate a polymeric microstructure, contacting (e.g., swelling or infusing) the polymeric microstructure with a carbon precursor component (e.g., incorporating a carbon precursor component into the polymeric microstructure) and pyrolyzing the polymeric microstructure to generate a conductive pyrolytic carbon microstructure with a conductive component positioned therein. In some instances, the pyrolytic carbon microstructure is an interpenetrating network that forms a homogeneous pyrolytic carbon material. Conductive pyrolytic carbon microstructures having a conductive component positioned within prepared by the subject methods are also disclosed. Microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate) are also provided.

[0049] Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0050] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0051] Certain ranges are presented herein with numerical values being preceded by the term "about." The term "about" is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrecited number may be a number which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number.

[0052] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

[0053] All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

[0054] It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

[0055] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.

[0056] While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 U.S.C. §112, are not to be construed as necessarily limited in any way by the construction of "means" or "steps" limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 U.S.C. §1 12 are to be accorded full statutory equivalents under 35 U.S.C. §1 12.

[0057] As summarized above, the present disclosure provides methods for making a conductive pyrolytic carbon microstructure, such as one having a conductive pyrolytic carbon polymer positioned therein (e.g., a pyrolytic carbon microstructure having a conductive pyrolyzed carbon formed from the pyrolysis of a stabilized cyclized polyacrylonitrile polymer). In further describing embodiments of the disclosure, methods including generating a conductive pyrolytic microstructure having a conductive component positioned within are first described in greater detail. Next, conductive pyrolytic carbon microstructures having a conductive component positioned within prepared by the subject methods are also described. Microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate) are also provided.

[0058] METHODS FOR MAKING A CONDUCTIVE PYROLYTIC CARBON MICROSTRUCTURE

[0059] Aspects of the present disclosure include methods for making a conductive pyrolytic carbon microstructure (e.g., with a conductive component such as a conductive pyrolytic carbon polymer positioned therein formed by in situ polymerization of a non- conductive polymer within a polymeric microstructure) followed by pyrolysis. Methods according to certain embodiments include irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition having a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface, displacing the build elevator away from the build surface, irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second non-polymerized region in contact with the build surface. These steps are repeated in a manner sufficient to generate a polymeric structure. For example, the steps may be repeated 2 or more times, such as 3 or more times, such as 4 or more times, such as 5 or more times, such as 10 or more times, such as 20 or more times, such as 30 or more times, such as 40 or more times, such as 50 or more times, such as 100 or more times, such as 250 or more times, such as 500 or more times and including 1000 or more times.

[0060] In embodiments, the polymerizable composition is provided to the space between the build elevator and build surface of the liquid interface production module with a source of a polymerizable material. In some instances, the polymerizable composition may be provided directly to the build plate from a liquid conduit and reservoir system. In some embodiments, the carrier includes one or more feed channels therein. The carrier feed channels are in fluid communication with the polymerizable composition source, for example a reservoir and associated pump. Different carrier feed channels may be in fluid communication with the same supply and operate simultaneously with one another, or different carrier feed channels may be separately controllable from one another (for example, through the provision of a pump and / or valve for each). Separately controllable feed channels may be in fluid communication with a source (e.g., reservoir) containing the same polymerizable composition, or may be in fluid communication with a reservoir containing different polymerizable compositions. Through the use of valve assemblies, different polymerizable compositions may in some embodiments be alternately fed through the same feed channel, if desired. In some embodiments, methods include injecting the polymerizable composition through the conduit with a syringe pump.

[0061] In some embodiments, the polymerizable composition is conveyed to the space between the build elevator and the build surface through two or more conduits, such as 3 or more, such as 4 or more, such as 5 or more, such as 6 or more, such as 7 or more, such as 8 or more, such as 9 or more and including through 10 or more different conduits. In some instances, the conduit is positioned internal to the generated polymeric structure. In other instances, the conduit is positioned external to the generated polymeric structure. In certain instances, one or more of the conduits passes through the build elevator, such as 2 or more of the conduits, such as 3 or more of the conduits and including where polymerizable composition is conveyed through 5 or more of the conduits that pass through the build elevator.

[0062] In some embodiments, methods include conveying two or more different polymerizable materials into the space between the build elevator and the build surface. In some instances, a first polymerizable material is conveyed through a first conduit into the space between the build elevator and the build surface and a second polymerizable material is conveyed through a second conduit into the space between the build elevator and the build surface. In certain embodiments, a plurality of different polymerizable materials is conveyed through a plurality of different conduits into the space between the build elevator and the build surface. For example, the number of different polymerizable materials conveyed may be 2 or more, such as 3 or more, such as 4 or more, such as 5 or more, such as 6 or more, such as 7 or more, such as 8 or more, such as 9 or more and including 10 or more. In some instances, the plurality of polymerizable materials is conveyed through 2 or more different conduits, such as 3 or more, such as 4 or more, such as 5 or more, such as 6 or more, such as 7 or more, such as 8 or more, such as 9 or more and including 10 or more different conduits.

[0063] The two or more different polymerizable materials may be conveyed into the space between the build elevator and the build surface simultaneously or in a predetermined sequential order. In some instances, two or more different polymerizable materials are conveyed into the space between the build elevator and the build surface, such as to form a blend or mixture of the two or more different polymerizable materials (i.e., a mixed resin). In other instances, two or more different polymerizable materials are conveyed sequentially into the space between the build elevator and the build surface, such as to form layers of different polymerizable materials.

[0064] The polymerizable composition may be conveyed through each conduit at a rate that varies, such as from 0.01 pL / s to 200 pL / s, such as from 0.05 pL / s to 150 pL / s, such as from 0.1 pL / s to 100 pL / s, such as from 0.5 pL / s to 90 pL / s, such as from 1 pL / s to 80 pL / s, such as from 2 pL / s to 70 pL / s, such as from 3 pL / s to 60 pL / s, such as from 4 pL / s to 50 pL / s, such as from 5 pL / s to 40 pL / s, such as from 6 pL / s to 30 pL / s and including from 7 pL / s to 27 pL / s. In some instances, the rate for conveying the polymerizable composition is controlled by a syringe pump. In some instances, the rate may be controlled by a rate-limiting valve positioned at a proximal or distal end of the conduit. In certain embodiments, the polymerizable composition is conveyed into the space between the build elevator and the build surface at a rate sufficient to generate the polymeric structure at a rate of 0.01 mm / hr or more, such as 0.05 mm / hr or more, such as 0.1 mm / hr or more, such as 0.5 mm / hr or more, such as 1 mm / hr or more, such as 2 mm / hr or more, such as 3 mm / hr or more, such as 4 mm / hr or more, such as 5 mm / hr or more, such as 6 mm / hr or more, such as 7 mm / hr or more, such as 8 mm / hr or more, such as 9 mm / hr or more, such as 10 mm / hr or more, such as 15 mm / hr or more, such as 20 mm / hr or more, such as 25 mm / hr or more, such as 50 mm / hr or more, such as 75 mm / hr or more, such as 100 mm / hr or more, such as 150 mm / hr or more and including conveying the polymerizable composition through one or more conduits into the space between the build elevator and the build surface at a rate sufficient to generate the polymeric structure at a rate of 250 mm / hr or more. For example, the polymerizable material may be conveyed through one or more conduits at a rate sufficient to generate the polymeric structure at a rate of 1 mm / hr to 250 mm / hr, such as from 2 mm / hr to 225 mm / hr, such as from 3 mm / hr to 200 mm / hr, such as from 4 mm / hr to 175 mm / hr, such as from 5 mm / hr to 150 mm / hr and including from 10 mm / hr to 125 mm / hr.

[0065] The polymerizable composition may include one or more different polymerizable materials, such as a polymerizable material selected from polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, aliphatic urethane acrylate, polycaprolactone, polyglycolic acid, polylactic acid, polylactic-co-glycolic acid, polyethylene glycol, polyethylene glycol dimethacrylate (PEGDMA), polystyrene, divinylbenzene, thiol-enes, anhydrides, polyacrylic acid, poly methylmethacrylate, poly(diaminonaphthalene), trimethylolpropane triacrylate (TMPTA) monomer, polyvinyl alcohol, polyvinylpyrrolidone, vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof. In certain instances, one or more of the polymerizable materials includes carbon nanotubes incorporated therein, such as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs). In certain embodiments, the polymerizable material includes an aliphatic urethane acrylate. In some instances, the polymerizable composition conveyed through the conduit has a viscosity of from 100 cP to 7000 cP, such as from 150 cP to 6500 cP, such as from 200 cP to 6000 cP, such as from 250 cP to 5500 cP, such as from 300 cP to 5000 cP, such as from 350 cP to 4500 cP, such as from 400 cP to 4000 cP, such as from 450 cP to 3500 cP and including a viscosity of from 500 cP to 3000 cP.

[0066] In some embodiments, the lattice microstructures of the polymeric microstructures described herein have 2 or more repeating lattice cell units, such as 3 or more repeating lattice cell units, such as 4 or more repeating lattice cell units and including 5 or more repeating lattice cell units. In some instances, the lattice microstructure has a lattice shape selected from tetrahedral, Kagome, rhombic, icosahedral, Voronoi, octet, or triangular. In some instances, the lattice microstructure is composed of two or more lattice cell units having different lattice shapes, such where the lattice microstructure is composed of 3 or more different lattice shapes, such as 4 or more different lattice shapes and including where the lattice microstructure is composed of 5 or more different lattice shapes.

[0067] In some embodiments, the lattice microstructure is formed from lattice cells having a unit size of from 1 pm to 1000 pm, such as from 5 pm to 950 pm, such as from 10 pm to 900 pm, such as from 15 pm to 850 pm, such as from 20 pm to 800 pm, such as from 25 pm to 750 pm, such as from 30 pm to 700 pm, such as from 35 pm to 650 pm, such as from 40 pm to 600 pm, such as from 45 pm to 550 pm and including from 50 pm to 500 pm, for example from 200 pm to 500 pm. In embodiments, the lattice microstructure has a volume of from 0.01 pL to 25 pL, such as from 0.02 pL to 24.5 pL, such as from 0.03 pL to 24 pL, such as from 0.04 pL to 23.5 pL, such as rom 0.05 pL to 23 pL, such as from 0.6 pL to 22.5 pL, such as from 0.07 pL to 22 pL, such as from 0.08 pL to 21 .5 pL, such as from 0.09 pL to 21 pL, such as from 0.1 pL to 20 pL, such as from 0.5 pL to 19 pL, such as from 1 pL to 18 pL, such as from 2 pL to 17 pL, such as from 3 pL to 16 pL and including from 4 pL to 15 pL. The polymeric structure may be configured to contain a composition within the lattice microstructure (e.g., a fluidic composition) where in some embodiments the lattice microstructure is configured to contain a volume of from 0.1 pL to 25 pL, such as from 0.2 pL to 24 pL, such as from 0.3 pL to 23 pL, such as from 0.4 pL to 22 pL, such as rom 0.5 pL to 21 pL, such as from 0.6 pL to 20 pL, such as from 0.7 pL to 19 pL, such as from 0.8 pL to 18 pL, such as from 0.9 pL to 17 pL and including where the lattice microstructure is configured to contain a volume of from 1 pL to 15 pL.

[0068] In some embodiments, the density of lattice cell units remains constant throughout the lattice microstructure of the polymeric structures. In other embodiments, the density of lattice cell units varies at one or more parts the lattice microstructure. In some embodiments, the lattice microstructure contains regions of increased lattice cell density, such as where the lattice cell density in these regions is increased by 1% or more across the longitudinal axis of the lattice microstructure, such as by 2% or more, such as by 3% or more, such as by 4% or more, such as by 5% or more, such as by 10% or more, such as by 20% or more, such as by 30% or more, such as by 40% or more and including by 50% or more. In some instances, the regions of increased lattice cell density are present at various increments across the longitudinal axis of the lattice microstructure. For example, the regions of increased lattice cell density may be present at increments of every 0.01 pm or more, such as 0.05 pm or more, such as 0.1 pm or more, such as 0.5 pm or more, such as 1 pm or more, such as 2 pm or more, such as 3 pm or more, such as 4 pm or more, such as 5 pm or more, such as 6 pm or more, such as 7 pm or more, such as 8 pm or more, such as 9 pm or more, such as 10 pm or more across the longitudinal axis of the lattice microstructure, such as every 15 pm or more, such as every 20 pm or more, such as every 30 pm or more, such as every 40 pm or more and including every 50 pm or more.

[0069] In some instances, the density of lattice cell units exhibits a gradient in one or more parts of the lattice microstructure. In certain instances, the density of lattice cell units gradually increases across a longitudinal axis of the lattice microstructure. For example, the density of the lattice cell units may increase by 1% or more across the longitudinal axis of the lattice microstructure, such as by 2% or more, such as by 3% or more, such as by 4% or more, such as by 5% or more, such as by 10% or more, such as by 20% or more, such as by 30% or more, such as by 40% or more and including by 50% or more. In some embodiments, the density of the lattice cell units increases at predetermined increments across the longitudinal axis of the lattice microstructure, such as where the density of the lattice cell units increases every 1% or more of the length across the longitudinal axis of the lattice microstructure, such as every 2% or more, such as every 3% or more, such as every 4% or more, such as every 5% or more, such as every 6% or more, such as every 7% or more, such as every 8% or more, such as every 9% or more and including every 10% or more. Depending on the size of the lattice microstructure, the density of the lattice cell units may increase every 1 pm or more across the longitudinal axis, such as every 2 pm or more, such as every 3 pm or more, such as every 4 pm or more, such as every 5 pm or more, such as every 10 pm or more, such as every 20 pm or more, such as every 30 pm or more, such as every 40 pm or more and including every 50 pm or more. For example, the density of the lattice cell units may increase by 1% or more every 25 pm or more across the longitudinal axis of the lattice microstructure, such as by 2% or more every 25 pm or more across the longitudinal axis of the lattice microstructure, such as 5% or more every 25 gm or more across the longitudinal axis of the lattice microstructure.

[0070] In some embodiments, the lattice microstructure includes a plurality of struts. Struts according to certain embodiments provide mechanical integrity to the lattice microstructure. In some instances, struts have a thickness which range from 1 gm to 200 pm, such as from 2 pm to 190 pm, such as from 3 pm to 180 pm, such as from 4 pm to 170 pm, such as from 5 pm to 160 pm, such as from 6 pm to 150 pm, such as from 7 pm to 140 pm, such as from 8 pm to 130 pm, such as from 9 pm to 120 pm and including from 10 pm to 100 pm. For instance, the strut size may be in certain examples from 50 pm to 100 pm such as 70 pm to 90 pm.

[0071] In some instances, the polymer structure includes a plurality of microchannels. In some instances, one or more of the microchannels includes one or more bifurcations, such as 2 or more bifurcations, such as 3 or more, such as 4 or more, such as 5 or more and including 10 or more different bifurcations. In some instances, the microchannels extend through the polymeric structure. In some instances, the microchannels are fluidically interconnected. In some instances, the polymeric structure has a single network of fluidically interconnected microchannel networks. In other instances, the polymeric structure has a plurality of fluidically interconnected microchannel networks.

[0072] In some embodiments, the polymerizable composition in the space between the build elevator and the build surface of the liquid interface production module is irradiated with a light beam generator component of a micro-digital light projection system. In some instances, the light source is a broadband light source that emits light having wavelengths from 400 nm to 1000 nm. In some instances, the broadband light source is a halogen lamp, deuterium arc lamp, xenon arc lamp, stabilized fiber-coupled broadband light source, a broadband LED with continuous spectrum, super-luminescent emitting diode, semiconductor light emitting diode, wide spectrum LED white light source, a multiLED integrated white light source, among other broadband light sources or any combination thereof. In some instances, the light source is a narrow band light source emitting a particular wavelength or a narrow range of wavelengths. In some instances, the narrow band light sources emit light having a narrow range of wavelengths, such as for example, 50 nm or less, such as 40 nm or less, such as 30 nm or less, such as 25 nm or less, such as 20 nm or less, such as 15 nm or less, such as 10 nm or less, such as 5 nm or less, such as 2 nm or less and including light sources which emit a specific wavelength of light. In some instances, the polymerizable composition is irradiated with a narrow band light source such as a narrow wavelength LED, laser diode or a broadband light source coupled to one or more optical bandpass filters, diffraction gratings, monochromators or any combination thereof.

[0073] In certain embodiments, the light source is a stroboscopic light source and the polymerizable composition is illuminated with periodic flashes of light, such as where the polymerizable composition is irradiated at a frequency of 0.01 kHz or greater, such as 0.05 kHz or greater, such as 0.1 kHz or greater, such as 0.5 kHz or greater, such as 1 kHz or greater, such as 2.5 kHz or greater, such as 5 kHz or greater, such as 10 kHz or greater, such as 25 kHz or greater, such as 50 kHz or greater and including 100 kHz or greater. In certain instances, the polymerizable composition is irradiated with a laser, such as pulsed laser or a continuous wave laser.

[0074] In some embodiments, the polymerizable composition is in contact with the build elevator and the build surface. In some instances, methods include irradiating the polymerizable composition for 1 second or longer to bond the first polymerized region of the polymerizable composition to the build elevator, such as from 5 seconds longer, such as for 10 seconds or longer, such as for 20 seconds or longer, such as for 30 seconds or longer, such as for 1 minute or longer, such as for 5 minutes or longer and including for 10 minutes or longer.

[0075] In some embodiments, the build elevator is displaced away from the build surface after the first polymerized region of the polymerizable composition is bonded to the build elevator. In some instances, the build elevator is displaced in increments of 0.001 pm or more, such as 0.005 pm or more, such as 0.01 pm or more, such as 0.05 pm or more, such as 0.1 pm or more, such as 0.5 pm or more, such as 1 pm or more, such as 2 pm or more, such as 3 pm or more, such as 4 pm or more, such as 5 pm or more and including in increments of 10 pm or more. In certain instances, the build elevator is displaced in increments of from 0.001 pm to 20 pm, such as from 0.005 pm to 19 pm, such as from 0.01 pm to 18 pm, such as from 0.05 pm to 17 pm, such as from 0.1 pm to 16 pm, such as from 0.2 pm to 17 pm, such as from 0.3 pm to 16 pm, such as from 0.4 pm to 15 pm, such as from 0.5 pm to 14 m, such as from 0.6 pm to 13 pm, such as from 0.7 pm to 12 pm, such as from 0.8 pm to 11 pm and including from 0.9 pm to 10 pm.

[0076] In certain instances, polymerizable composition is added to the build surface after each displacement of the build elevator away from the build surface. In some instances, the polymerizable composition is continuously added to the build surface. In other instances, the polymerizable composition is added to the build surface in discreet intervals each having a predetermined amount. In some embodiments, the polymerizable composition includes polyethylene glycol) diacrylate (PEGDA), 1 ,6- hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, or an aliphatic urethane acrylate. In some embodiments, the polymerizable composition is selected from polycaprolactone, polyglycolic acid, polylactic acid, polystyrene, divinylbenzene, poly(diaminonaphthalene), polylactic-co-glycolic acid, polyethylene glycol, thiol-enes, anhydrides, polyacrylic acid, poly methylmethacrylate, polyvinyl alcohol, polyvinylpyrrolidone, vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof.

[0077] In embodiments, methods include irradiating the polymerizable composition. In some embodiments, the polymerizable composition is irradiated through the build surface. In some instances, the polymerizable composition is irradiated in the presence of a polymerization inhibitor. In certain embodiments, the polymerizable composition is continuously polymerized while displacing the build elevator away from the build surface. In certain cases, the polymerization inhibitor is oxygen and the build surface is permeable to oxygen. In certain instances, polymerizing the polymerizable composition in the presence of a polymerization inhibitor such as oxygen enables continuous (i.e. , not layer-by-layer) generation the lattice microstructure with a liquid “dead zone” at the interface between the build surface and the building polymeric structure. In some instances, the dead zone is generated because oxygen acts as a polymerization inhibitor, passing through the oxygen-permeable build surface. Photopolymerization cannot occur in the oxygen containing “dead zone” region such that this region remains fluid, and the polymerized component in contact with the build surface so that the building microstructure does not physically attach to the build surface. Displacement of the build elevator therefore generates a continuous polymeric microstructure having a microchannel which exhibits sufficient mechanical integrity and surface isotropicity.

[0078] In some embodiments, the polymerizable composition is in contact with the build elevator and the build surface. In some instances, the method includes irradiating the polymerizable composition for a duration sufficient to bond the first polymerized region of the polymerizable composition to the build elevator. In some instances, the build elevator is displaced in predetermined increments of from 0.5 pm to 1 .0 pm. In some instances, the methods include adding polymerizable composition to the build surface after each displacement of the build elevator away from the build surface. In some instances, methods include continuously adding polymerizable composition to the build surface. In some instances, the polymerizable composition is continuously added to the build surface by injection through a conduit.

[0079] In certain embodiments, the polymerizable composition is polymerized using a liquid interface polymerization module that is part of a continuous liquid interface production (CLIP) system such as that described in International Patent Publication No. WO 2014 / 126837; U.S. Patent Publication Nos. 2018 / 0064920; 2017 / 0095972; 2021 / 0246252 and U.S. Patent Publication Nos. 10,155,882; 10,792,857, the disclosures of which are herein incorporated by reference.

[0080] In some embodiments, methods include irradiating the polymerizable composition with a micro-digital light projection system. In some instances, methods include determining a focal plane on the build surface using the micro-digital light projection system. In some embodiments, determining the focal plane on the build surface includes irradiating the build surface with a stroboscopic light source through the tube lens and displacing the build surface until the light is focused on the build surface through the tube lens. In certain embodiments, methods for determining the focal plane on the build surface includes irradiating build surface with the stroboscopic light source with periodic flashes of light. For example, the frequency of each light pulse may be 0.0001 kHz or greater, such as 0.0005 kHz or greater, such as 0.001 kHz or greater, such as 0.005 kHz or greater, such as 0.01 kHz or greater, such as 0.05 kHz or greater, such as 0.1 kHz or greater, such as 0.5 kHz or greater, such as 1 kHz or greater, such as 2.5 kHz or greater, such as 5 kHz or greater, such as 10 kHz or greater, such as 25 kHz or greater, such as 50 kHz or greater and including 100 kHz or greater. In certain instances, the frequency of pulsed irradiation by the light source ranges from 0.00001 kHz to 1000 kHz, such as from 0.00005 kHz to 900 kHz, such as from 0.0001 kHz to 800 kHz, such as from 0.0005 kHz to 700 kHz, such as from 0.001 kHz to 600 kHz, such as from 0.005 kHz to 500 kHz, such as from 0.01 kHz to 400 kHz, such as from 0.05 kHz to 300 kHz, such as from 0.1 kHz to 200 kHz and including from 1 kHz to 100 kHz. The duration of light irradiation for each light pulse (i.e., pulse width) may vary and may be 0.000001 ms or more, such as 0.000005 ms or more, such as 0.00001 ms or more, such as 0.00005 ms or more, such as 0.0001 ms or more, such as 0.0005 ms or more, such as 0.001 ms or more, such as 0.005 ms or more, such as 0.01 ms or more, such as 0.05 ms or more, such as 0.1 ms or more, such as 0.5 ms or more, such as 1 ms or more, such as 2 ms or more, such as 3 ms or more, such as 4 ms or more, such as 5 ms or more, such as 10 ms or more, such as 25 ms or more, such as 50 ms or more, such as 100 ms or more and including 500 ms or more. For example, the duration of light irradiation may range from 0.000001 ms to 1000 ms, such as from 0.000005 ms to 950 ms, such as from 0.00001 ms to 900 ms, such as from 0.00005 ms to 850 ms, such as from 0.0001 ms to 800 ms, such as from 0.0005 ms to 750 ms, such as from 0.001 ms to 700 ms, such as from 0.005 ms to 650 ms, such as from 0.01 ms to 600 ms, such as from 0.05 ms to 550 ms, such as from 0.1 ms to 500 ms, such as from 0.5 ms to 450 ms, such as from 1 ms to 400 ms, such as from 5 ms to 350 ms and including from 10 ms to 300 ms. In some instances, methods include irradiating the build surface with a plane of light having a projected image pattern with the stroboscopic light source.

[0081] In some embodiments, the carbon precursor component further includes one or more metals. In some instances, the precursor component includes a reactive precursor. In some instances, the carbon precursor component includes a carbohydrate such as sucrose, fructose, ribose, glucose, xylose, starch, etc. In some instances, the carbohydrate component (e.g., glucose) is infused or swelled into the polymeric microstructure. In some instances, the carbohydrate is simultaneously infused and carbonized in the polymeric microstructure via a solvothermal process. In some instances, the swelling takes place in solution prior to the solvothermal carbonization process. In some instances, the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to react carbonaceous solvothermal derivatives with vinyl groups, e.g., via a Diels-Alder cycloaddition reaction, positioned on the polymeric microstructure. In some instances, the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to generate one or more aromatic moieties on the polymeric microstructure, e.g., via a Diels-Alder cycloaddition reaction.

[0082] In some embodiments, a non-conductive polymer is polymerized within the polymeric microstructure from polymeric precursors swelled into the internal cavities of the polymeric microstructure. Pyrolysis of the polymeric microstructure with incorporated non-conductive polymer forms the pyrolytic carbon microstructure with a conductive pyrolytic carbon polymer positioned therein.

[0083] In some embodiments, the carbon precursor component is a polymeric precursor. In some instances, a polymeric precursor is contacted with the polymeric microstructure. In some embodiments, the polymeric precursor is an acrylonitrile. In some instances, the non-conductive polymer formed by polymerization (e.g., in situ within the polymeric microstructure) is a polyacrylonitrile. In some instances, pyrolysis of the polymeric microstructure with the non-conductive polymer positioned within forms a conductive pyrolytic carbon lattice from the non-conductive polymer, such as a conductive pyrolytic carbon 3D lattice. In some instances, carbonization of the non- conductive polymer forms a stabilized polymer such as by cyclization stabilization of a polyacrylonitrile polymer. In certain instances, carbonization forms a 3D lattice of cyclized conductive polymer (e.g., 3D lattice formed by cyclization of polyacrylonitrile).

[0084] In some instances, contacting the polymeric precursor is sufficient to incorporate the polymeric precursor within the internal cavities of the polymeric microstructure. In some instances, contacting the polymeric precursor with the polymeric microstructure includes swelling or infusing the polymeric microstructure with the polymeric precursor. In some instances, the polymeric precursor is swelled into the polymeric microstructure with a solvent, such as with dimethyl sulfoxide (DMSO). In certain instances, the polymeric precursor is combined into a composition that includes a solvent (e.g., DMSO) and a radical initiator (e.g., a thermal initiator or a photo-initiator) such as azobisisobutyronitrile (AIBN)). In certain instances, the polymeric precursor is combined in a composition that includes a crosslinker (e.g. polyethylene glycol) diacrylate).

[0085] In embodiments, the polymeric precursor is polymerized in situ within the polymeric microstructure. In some instances, polymerizing the polymeric precursor includes applying heat to the polymeric microstructure with the polymeric precursor (e.g., swelled polymeric microstructure). In some instances, the polymer microstructure with the polymeric precursor within is heated to a temperature of from 50 °C to 100 °C, such as from 60 °C to 80 °C. In some instances, the polymer microstructure with the polymeric precursor within is heated in the presence of a heating medium, such as one or more of mineral oil, dimethyl sulfoxide, argon gas and a fluorinated heat-transfer fluid.

[0086] In some instances, the non-conductive polymer within the polymeric microstructure is prepared for pyrolysis through an oxidative thermal treatment of the polymeric microstructure with the non-conductive polymer positioned within. In some instances, oxidative treatment includes applying heat to the polymeric microstructure with the non-conductive polymer in the presence of oxygen. In some instances, oxidative treatment includes heating to a temperature of from 150 °C to 350 °C, such as from 200 °C to 300 °C in the presence of oxygen. In some instances, the temperature is ramped at a rate of 0.01 °C / minute or more, such as by 0.05 °C / minute or more, such as by 0.1 °C / minute or more, such as by 0.5 °C / minute or more, such as by 1 °C / minute or more, such as by 2 °C / minute or more, such as by 3 °C / minute or more, such as by

[0087] 4 °C / minute or more, such as by 5 °C / minute or more, such as by 6 °C / minute or more, such as by 7 °C / minute or more, such as by 8 °C / minute or more, such as by

[0088] 9 °C / minute or more and including by 10 °C / minute or more. In some instances, the temperature is ramped at a rate of from 0.1 °C / minute to 10 °C / minute, such as from 3 °C / minute to 9 °C / minute, such as from 4 °C / minute to 8 °C / minute and including

[0089] 5 °C / minute. The oxidative treatment may be applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of 20 minutes or more, such as 30 minutes or more, such as 60 minutes or more, such as 90 minutes or more, such as 120 minutes or more and including 180 minutes or more. In some instances, the oxidative treatment is applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of from 20 minutes to 120 minutes, such as from 30 minutes to 90 minutes and including oxidative treatment for about 60 minutes.

[0090] In embodiments, the generated polymeric microstructure is pyrolyzed to generate a pyrolytic carbon microstructure having a conductive component positioned therein. The term “pyrolyzed” is used herein in its conventional sense to refer to process of thermal carbonization (e.g., decomposition) through heating at a high temperature. In some instances, the polymeric microstructure is pyrolyzed in a manner sufficient to generate a pyrolytic carbon microstructure of monolithic hard carbon. In some instances, the polymeric microstructure is pyrolyzed by heating under an inert atmosphere. In some instances, the polymeric microstructure is pyrolyzed by heating under vacuum. In other instances, the polymeric microstructure is pyrolyzed by heating under an inert gas selected from nitrogen, argon and helium. In some embodiments, the polymeric microstructure is heated to a temperature of 300 °C or more, such as 400 °C or more, such as 500 °C or more, such as 600°C or more, such as 700 °C or more, such as 800 °C or more, such as 900 °C or more, such as 1000 °C or more, such as 1 100 °C or more, such as 1200 °C or more, such as 1300 °C or more, such as 1400 °C or more, such as 1500 °C or more and including 1600 °C or more. In some instances, pyrolysis includes heating to a temperature of from 300 °C to 1600 °C, such as from 400 °C to 1000 °C. In some instances, the temperature is ramped at a rate of 0.01 °C / minute or more, such as by 0.05 °C / minute or more, such as by 0.1 °C / minute or more, such as by 0.5 °C / minute or more, such as by 1 °C / minute or more, such as by 2 °C / minute or more, such as by 3 °C / minute or more, such as by 4 °C / minute or more, such as by 5 °C / minute or more, such as by 6 °C / minute or more, such as by 7 °C / minute or more, such as by 8 °C / minute or more, such as by 9 °C / minute or more and including by 10 °C / minute or more. In some instances, the temperature is ramped at a rate of from 0.1 °C / minute to 10 °C / minute, such as from 3 °C / minute to 9 °C / minute, such as from 4 °C / minute to 8 °C / minute and including 5 °C / minute.

[0091] FIG. 1 depicts the pyrolysis of a polymeric microstructure to a conductive pyrolytic carbon microstructure according to certain embodiments. In some instances, the polymer lattice is pyrolyzed to form a porous carbon lattice. In some instances, pyrolysis includes an initial low-temperature heating stage which forms the carbonaceous backbone followed by a high-temperature heating stage resulting in the graphitization to sheets of 6-membered carbon rings. For example, the polymer lattice may be pyrolyzed by heating at 1 .5 °C per minute under nitrogen to 400 °C, holding the temperature at 400 °C for 20 minutes followed by heating 2.5 °C per minute under nitrogen to 900 °C. In some embodiments, the pyrolytic carbon is composed of three- dimensionally arranged, curved graphene sheets.

[0092] In certain embodiments, pyrolysis methods include an isothermal hold after the oxidative treatment of the polymeric microstructure with non-conductive polymer positioned within and before heating to the final upper pyrolysis temperature. In some instances, the isothermal hold includes maintaining the polymeric microstructure with non-conductive polymer positioned within at a temperature from 300 °C to 450 °C, such as from 325 °C to 425 °C under an inert atmosphere, such as under nitrogen (N2) gas. The isothermal hold may be applied for a duration of 20 minutes or more, such as 30 minutes or more, such as 60 minutes or more, such as 90 minutes or more, such as 120 minutes or more and including 180 minutes or more. In some instances, the isothermal hold is applied to the polymeric microstructure with non-conductive polymer positioned within for a duration of from 20 minutes to 120 minutes, such as from 30 minutes to 90 minutes and including an isothermal hold for about 60 minutes.

[0093] Pyrolysis may include heating for 1 minute or more, such as for 2 minutes or more, such as for 3 minutes or more, such as for 4 minutes or more, such as for 5 minutes or more, such as for 10 minutes or more, such as for 15 minutes or more, such as for 30 minutes or more, such as for 45 minutes or more, such as for 60 minutes or more, such as for 90 minutes or more and including heating the polymeric microstructure for 120 minutes or more. Pyrolysis may be a duration of 1 hour or more, such as for 2 hours or more, such as for 3 hours or more, such as for 4 hours or more, such as for 5 hours or more and including for 6 hours or more.

[0094] In some embodiments, the polymeric microstructure is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 50% or more, such as by 55% or more, such as by 60% or more, such as by 65% or more, such as by 70% or more, such as by 75% or more, such as by 80% or more, such as by 85% or more, such as by 90% or more and including by 95% or more. In some instances, the polymeric microstructure is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 50% or less, such as by 45% or less, such as by 40% or less, such as by 35% or less, such as by 30% or less, such as by 25% or less, such as by 20% or less, such as by 15% or less, such as by 10% or less and including by 5% or less.

[0095] In some embodiments, pyrolyzing the polymeric microstructure generates a conductive pyrolytic carbon microstructure metal composite. In some instances, the method includes contacting the conductive pyrolytic carbon microstructure with carbon nanotubes, carbon nanofibers or a combination thereof. In some instances, a layer of carbon nanotubes, carbon nanofibers or combination thereof is formed on a surface of the pyrolytic carbon microstructure. In some instances, a layer of carbon nanotubes, carbon nanofibers, or a combination thereof is grown on the surface of the pyrolytic carbon microstructure. In some instances, the CNTs / CNFs are grown from an externally supplied hydrocarbon gas, such as ethylene, at the surface of a metal catalyst deposited prior to pyrolysis. In some instances, the hydrocarbon byproducts generated during the decomposition of the polymer form a small amount of CNTs / CNFs. In some instances, the catalyst species are reduced by a reducing gas, such as H2or carbon during the pyrolysis by carbothermal reduction. The catalyst may be deposited on the polymer template prior to pyrolysis, or after pyrolysis. The layer of carbon nanotubes, carbon nanofibers or combination thereof may have a thickness of 0.001 pm or more, such as 0.005 pm or more, such as 0.01 pm or more, such as 0.05 pm or more, such as 0.1 pm or more, such as 0.5 pm or more, such as 1 pm or more, such as 5 pm or more, such as 10 pm or more, such as 15 pm or more, such as 25 pm or more and including 100 pm or more. In some instances, the layer of carbon nanotubes, carbon nanofibers or combination thereof has a thickness of from 1 pm to 1000 pm, such as from 5 pm to 950 pm, such as from 10 pm to 900 pm, such as from 15 pm to 850 pm, such as from 20 pm to 800 pm, such as from 25 pm to 750 pm, such as from 30 pm to 700 pm, such as from 35 pm to 650 pm, such as from 40 pm to 600 pm, such as from 45 pm to 550 pm and including from 50 pm to 500 pm, for example from 200 pm to 500 pm

[0096] In some instances, methods include contacting the conductive pyrolytic carbon microstructure with an active material. In certain instances, the active material is electrografted to the conductive pyrolytic carbon microstructure. In certain instances, the active material is electro-grafted to the layer of carbon nanotubes, carbon nanofibers or combination thereof on the surface of the pyrolytic carbon microstructure. In some instances, electro-grafting of the active material to the conductive pyrolytic carbon microstructure is sufficient to generate a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0097] In some embodiments, pyrolysis of the non-conductive polymer positioned within the polymeric microstructure is sufficient to form a conductive pyrolytic carbon polymer. In some instances, the conductive pyrolytic carbon polymer has an electrical conductivity that is 50% or greater as compared to the electrical conductivity of the non-conductive polymer, such as 60% or greater, such as 70% or greater, such as 80% or greater, such as 90% or greater, such as 99% or more greater, such as 2-fold or greater, such as 5- fold or greater, such as 10-fold or greater, such as 50-fold or greater, such as 100-fold or greater, such as 500-fold or greater, such as 103-fold or greater, such as 104-fold or greater, such as 105-fold or greater, such as 106-fold or greater and including an electrical conductivity that is 109-fold or greater.

[0098] In some embodiments, the conductive pyrolytic carbon microstructure has an electrical conductivity that is 50% or greater as compared to the electrical conductivity of the polymeric microstructure, such as 60% or greater, such as 70% or greater, such as 80% or greater, such as 90% or greater, such as 99% or more greater, such as 2-fold or greater, such as 3-fold or greater, such as 4-fold or greater, such as 5-fold or greater and including 10-fold or greater.

[0099] In some instances, the conductive pyrolytic carbon microstructure exhibits a compressive strength that is 50% or greater as compared to the compressive strength of the polymeric microstructure, such as 60% or greater, such as 70% or greater, such as 80% or greater, such as 90% or greater, such as 2-fold or greater, such as 3-fold or greater, such as 4-fold or greater, such as 5-fold or greater and including 10-fold or greater. In some instances, the pyrolytic carbon microstructure exhibits a compressive strength that is 0.001 GPa or greater, such as 0.005 GPa or greater, such as 0.01 GPa or greater, such as 0.05 GPa or greater, such as 0.1 GPa or greater, such as 0.5 GPa or greater, such as 1 GPa or greater, such as 2 GPa or greater, such as 3 GPa or greater, such as 4 GPa or greater, such as 5 GPa or greater, such as 6 GPa or greater, such as 7 GPa or greater, such as 8 GPa or greater, such as 9 GPa or greater, such as 10 GPa or greater, such as 1 1 GPa or greater, such as 12 GPa or greater and including where the pyrolytic carbon microstructure exhibits a compressive strength that is 13 GPa or greater.

[0100] In some instances, the conductive pyrolytic carbon microstructure exhibits a mechanical integrity sufficient to be load bearing. Depending on the density of the lattice microstructure, in some embodiments the pyrolytic carbon microstructure exhibits a mechanical integrity sufficient to carry a load of 0.1 N or more, such as 0.5 N or more, such as 1 N or more, such as 2 N or more, such as 3 N or more, such as 4 N or more, such as 5 N or more, such as 10 N or more, such as 15 N or more, such as 20 N or more, such as 25 N or more, such as 50 N or more, such as 75 N or more and including 100 N or more. In some embodiments, the pyrolytic carbon microstructure includes one or more structural support struts which is positioned within the lattice microstructure to provide increased mechanical integrity, such as where the mechanical integrity is increased by 5% or more, such as by 25% or more and including by 75% or more. For example, the structural support struts may increase the load that the lattice microstructure can carry by 0.5 N or more, such as by 1 N or more, such as by 5 N or more, such as by 10 N or more, such as by 25 N or more, such as by 50 N or more and including by 100 N or more. In some instances, the structural support struts are positioned within the interior of the lattice microstructure. In other embodiments, the support struts are positioned along the exterior of the lattice microstructure.

[0101] CONDUCTIVE PYROLYTIC CARBON MICROSTRUCTURES

[0102] Aspects of the present disclosure also include conductive pyrolytic carbon microstructures (e.g., having a conductive component positioned therein) such as those prepared by the methods described hereinabove. In some instances, the pyrolytic carbon microstructure is monolithic hard carbon. In some instances, the pyrolytic carbon microstructure is an interpenetrating network that forms a homogeneous pyrolytic carbon material. The pyrolytic carbon microstructure may be any three-dimensional geometric shape including but are not limited to: rectilinear cross sectional shapes, e.g., squares, rectangles, trapezoids, triangles, hexagons, etc., curvilinear cross-sectional shapes, e.g., circles, ovals, etc., as well as irregular shapes, e.g., a parabolic bottom portion coupled to a planar top portion. Polymeric structures having a lattice microstructure of interest may have a length of from 0.1 pm to 5000 pm, such as from 0.5 pm to 4500 pm, such as from 1 pm to 4000 pm, such as from 2 pm to 3500 pm, such as from 3 pm to 3000 pm, such as from 4 pm to 2500 pm, such as from 5 pm to 2000 pm, such as from 6 pm to 1500 pm, such as from 7 pm to 1400 pm, such as from 8 pm to 1300 pm, such as from 9 pm to 1200 pm, such as from 10 pm to 1100 pm, such as from 50 pm to 2000 pm, such as from 75 pm to 1950 pm, such as from 100 pm to 1900 pm, such as from 125 pm to 1850 pm, such as from 150 pm to 1800 pm, such as from 175 pm to 1750 pm, such as from 200 pm to 1700 pm, such as from 225 pm to 1650 pm, such as from 250 pm to 1600 pm, such as from 275 pm to 1550 pm and including from 300 pm to 1500 pm. Polymeric structures having a lattice microstructure of interest may have a width of from 0.1 pm to 5000 pm, such as from 0.5 pm to 4500 pm, such as from 1 pm to 4000 pm, such as from 2 pm to 3500 pm, such as from 3 pm to 3000 pm, such as from 4 pm to 2500 pm, such as from 5 pm to 2000 pm, such as from 6 pm to 1500 pm, such as from 7 pm to 1400 pm, such as from 8 pm to 1300 pm, such as from 9 pm to 1200 pm, such as from 10 pm to 1100 pm, such as from 50 pm to 1000 pm, such as from 75 pm to 950 pm, such as from 100 pm to 900 pm, such as from 125 pm to 850 pm, such as from 150 pm to 800 pm, such as from 175 pm to 750 pm, such as from 200 pm to 700 pm, such as from 225 pm to 650 pm, such as from 250 pm to 600 pm, such as from 275 pm to 550 pm and including from 300 pm to 500 pm.

[0103] In some instances, the pyrolytic carbon microstructure includes one or more metals. In some instances, the conductive pyrolytic carbon components positioned therein includes hydrochar derived from the solvothermal decomposition of a carbohydrate such as sucrose, fructose, ribose, glucose, xylose, starch, etc., reacted with one or more vinyl groups, e.g., via a Diels-Alder cycloaddition reaction, positioned on the polymeric microstructure. In some instances, the conductive pyrolytic carbon microstructure includes carbon nanotubes, carbon nanofibers or a combination thereof. In some instances, the carbon nanotubes, carbon nanofibers or a combination thereof form a layer on a surface of the conductive pyrolytic carbon microstructure. In some instances, a layer of carbon nanotubes, carbon nanofibers or combination thereof is formed on a surface of the pyrolytic carbon microstructure. The layer of carbon nanotubes, carbon nanofibers or combination thereof may have a thickness of 0.001 pm or more, such as 0.005 pm or more, such as 0.01 pm or more, such as 0.05 pm or more, such as 0.1 pm or more, such as 0.5 pm or more, such as 1 pm or more, such as 5 pm or more, such as 10 pm or more, such as 15 pm or more, such as 25 pm or more and including 100 pm or more. In some instances, the layer of carbon nanotubes, carbon nanofibers or combination thereof has a thickness of from 1 pm to 1000 pm, such as from 5 pm to 950 pm, such as from 10 pm to 900 pm, such as from 15 pm to 850 pm, such as from 20 pm to 800 pm, such as from 25 pm to 750 pm, such as from 30 pm to 700 pm, such as from 35 pm to 650 pm, such as from 40 pm to 600 pm, such as from 45 pm to 550 pm and including from 50 pm to 500 pm, for example from 200 pm to 500 pm

[0104] In certain embodiments, the conductive pyrolytic carbon microstructure includes an active material. In some instances, the active material is electro -grafted to the conductive pyrolytic carbon microstructure. In certain instances, the active material forms a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0105] In some instances, the conductive pyrolytic carbon microstructure includes a conductive pyrolytic carbon polymer positioned within. In some instances, the conductive pyrolytic carbon polymer includes a conductive pyrolytic carbon lattice, such as a 3D lattice. In some instances, the non-conductive polymer is a polyacrylonitrile. In some instances, pyrolysis of the polymeric microstructure with the non-conductive polymer positioned within forms a conductive pyrolytic carbon lattice from the non- conductive polymer, such as a conductive pyrolytic carbon 3D lattice. In some instances, carbonization of the non-conductive polymer forms a stabilized polymer such as by cyclization stabilization of a polyacrylonitrile polymer. In certain instances, carbonization forms a 3D lattice of cyclized conductive polymer (e.g., 3D lattice formed by cyclization of polyacrylonitrile).

[0106] In some embodiments, the pyrolytic carbon microstructure having a conductive pyrolytic carbon polymer positioned therein is formed from pyrolysis of a polymeric microstructure formed from polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, urethane acrylate, polycaprolactone, polyglycolic acid, polylactic acid, polylactic-co-glycolic acid, polyethylene glycol, thiol-enes, anhydrides, polyacrylic acid, polystyrene, divinylbenzene, poly(diaminonaphthalene), polyacrylonitrile, poly methylmethacrylate, ethoxylated pentaerythritol tetraacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyhexanediol diacrylate, polyvinyl alcohol, polyvinylpyrrolidone, vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof and non-conductive polymer formed from polymerization (and in some instances, oxidative treatment) of polyacrylonitrile.

[0107] In some embodiments, the lattice microstructure of the pyrolytic carbon microstructure is formed from lattice cells having a unit size of from 1 pm to 1000 pm, such as from 5 pm to 950 pm, such as from 10 pm to 900 pm, such as from 15 pm to 850 pm, such as from 20 pm to 800 pm, such as from 25 pm to 750 pm, such as from 30 pm to 700 pm, such as from 35 pm to 650 pm, such as from 40 pm to 600 pm, such as from 45 pm to 550 pm and including from 50 pm to 500 pm, for example from 200 pm to 500 pm. In embodiments, the pyrolytic carbon microstructures have a volume of from 0.01 pL to 25 pL, such as from 0.02 pL to 24.5 pL, such as from 0.03 pL to 24 pL, such as from 0.04 pL to 23.5 pL, such as rom 0.05 pL to 23 pL, such as from 0.6 pL to 22.5 pL, such as from 0.07 pL to 22 pL, such as from 0.08 pL to 21.5 pL, such as from 0.09 pL to 21 pL, such as from 0.1 pL to 20 pL, such as from 0.5 pL to 19 pL, such as from 1 pL to 18 pL, such as from 2 pL to 17 pL, such as from 3 pL to 16 pL and including from 4 pL to 15 pL. In some embodiments, the pyrolytic carbon microstructure is configured to deliver a volume of from 0.1 pL to 25 pL, such as from 0.2 pL to 24 pL, such as from 0.3 pL to 23 pL, such as from 0.4 pL to 22 pL, such as rom 0.5 pL to 21 pL, such as from 0.6 pL to 20 pL, such as from 0.7 pL to 19 pL, such as from 0.8 pL to 18 pL, such as from 0.9 pL to 17 pL and including where the lattice microstructure is configured to contain a volume of from 1 pL to 15 pL. MICROELECTRODES HAVING CONDUCTIVE PYROLYTIC CARBON MICROSTRUCTURES

[0108] Aspects of the present disclosure also include microelectrodes having conductive pyrolytic carbon microstructures (e.g., where the conductive pyrolytic carbon microstructures are positioned on a substrate). In some instances, the microelectrodes have a high surface area and tailored lattice geometries. In some instances, the electrodes have one or more of: 1 ) flow-directing capabilities; and 2) controlled-ion intercalation. In some instances, microelectrodes are susceptors for electrification of thermochemical reactors. In some instances, the microelectrodes are electrocatalysis scaffolds or substrates. In other instances, the microelectrodes are lightweight aerospace structural materials.

[0109] In some instances, the microelectrode includes a substrate. In certain instances, the substrate is planar. In certain instances, the substrate is non-planar. In some instances, the substrate is conductive, such as a substrate formed from a metal. In some instances, the substrate is non-conductive, such as where the substrate is an insulator.

[0110] Microelectrodes of interest can have a variety of forms and be made from a variety of materials. For example, microelectrodes can be formed as plates, mesh, tubes or other shapes of conductive material. The microelectrode can also be a conductive film formed over an inert non-conducting base material formed in the shape of, for example, a plate, tube, or mesh. The conductive films can be formed on the non-conducting base material by a variety of methods, including, for example, sputtering, physical vapor deposition, plasma deposition, chemical vapor deposition, screen printing, and other coating methods.

[0111] The microelectrodes can further include a conductive material, such as, for example, metal, carbon, conductive polymer, or metallic compound. Suitable conductive materials for use in microelectrodes formed with the subject conductive pyrolytic carbon microstructures may be non-corroding and can include, for example, gold, vitreous carbon, graphite, platinum, ruthenium dioxide, and palladium, as well as other materials. Suitable non-conducting base materials for use in microelectrodes formed with the subject conductive pyrolytic carbon microstructures include plastic and polymeric materials, such as, for example, polyethylene, polypropylene, polyurethanes, and polyesters.

[0112] The conductive pyrolytic carbon microstructures and / or the optional nonconducting base material in microelectrodes of interest may be porous or microporous. For example, the conductive pyrolytic carbon microstructures and / or the optional nonconducting base material may be formed, for example, as a mesh, a reticulated structure, a microporous film, or a film that is permeable to a reductant or oxidant.

[0113] FIG. 2 depicts a microelectrode having a high surface area conductive pyrolytic carbon microstructure according to certain embodiments. The microelectrode provides for electrolyte flow capabilities where there is working ion transport through a membrane but restricts (or altogether inhibits) mediator crossover. As shown in the legend, the conductive pyrolytic carbon microstructure includes a nickel metal with a manganese oxide surface layer which provides for functional connectivity between a cathode / separator interface and current collector. The zinc concentration in the electrolyte increase closer to the cathode / separator interface. The Pe ratio can be calculated by the ratio of the convective transport rate (vL) to diffusive transport rate (D).

[0114] FIG. 3 depicts a printed susceptor having a conductive pyrolytic carbon microstructure according to certain embodiments. The conductive pyrolytic carbon microstructure includes surface catalysts which are functionally coupled to high frequency, high efficiency power electronics such as to absorb electromagnetic energy and convert it to heat. The susceptor has optimized electromagnetic properties such as tuned electrical conductivity, mechanical properties such as effective strength and durability as well as thermal properties such as tuned thermal conductivity. As shown in FIG. 3, the printed susceptor having the conductive pyrolytic carbon microstructure can be used with a flow through device.

[0115] KITS

[0116] Kits for use in practicing certain methods described herein are also provided. In certain embodiments, the kits include one or more structures having a pyrolytic carbon microstructure as well as pyrolytic carbon microstructures having a conductive component positioned therein as described above. In some embodiments, kits include one or more polymeric precursors (e.g., acrylonitrile) for polymerization in situ within the polymeric microstructure. In some instances, kits include a solvent (e.g., DMSO) as well as a radical initiator (e.g., AIBN). In certain instances, kits further includes a crosslinker (e.g. polyethylene glycol) diacrylate). In certain instances, the kits can include a heating medium such as a fluorinated heat transfer medium. In some instances, kits include one or more metals. In some instances, kits include carbon nanotubes, carbon nanofibers or a combination thereof. In some instances, kits can include an active material such as for electro-grafting to the conductive pyrolytic carbon microstructure. Kits may also include one or more substrates (e.g., planar or non-planar conductive or non-conductive) for preparing a microelectrode as described herein.

[0117] In certain embodiments, the kits will further include instructions for practicing the subject methods or means for obtaining the same (e.g., a website URL directing the user to a webpage which provides the instructions), where these instructions may be printed on a substrate, where substrate may be one or more of: a package insert, the packaging, reagent containers and the like. Yet another form of these instructions is a computer readable medium, e.g., diskette, compact disk (CD), portable flash drive, USB storage, DVD, Blu-ray disk, etc.), and the like, on which the information has been recorded. Yet another form of these instructions that may be present is a website address which may be used via the internet to access the information at a removed site.

[0118] EXPERIMENTAL

[0119] The following examples are offered by way of illustration and not by way of limitation.

[0120] Example 1 - Methods for fabrication of dual network polymers with high pyrolysis carbon yields via infusion of gels with monomers and subsequent in situ polymerization

[0121] A. Introduction

[0122] Subjecting polymers to a high temperature treatment called pyrolysis to convert them to conductive graphitic carbon material is becoming an increasingly important process in manufacturing for sustainable energy storage, carbon capture, and electrification applications.

[0123] Pyrolysis requires high surface area to volume structures to avoid mechanical integrity concerns that arise with thicker solid objects during pyrolysis due to volatile components escaping from deep inside the structures causing deformation as they escape. Thinner features better facilitate volatiles escaping during heating without deformation. However, traditional molding methods are not able to fabricate large objects with thin features, such as beam-based lattice structures, that achieve the desired high surface area to volume ratio characteristic. This is a direction where vat photopolymerization (VP) 3D-printing of structures with high surface area to volume ratios adds significant value to pyrolysis.

[0124] One of the most widely used materials in pyrolysis is polyacrylonitrile (PAN), which is a precursor for generating conductive high-strength carbon fibers that are commonly used in lightweight structural applications and have been incorporated into battery systems for sustainable energy storage. The pyrolysis of PAN from a nonconductive polymer to a conductive pyrolytic carbon via an intermediate cyclization of linear PAN chains has been extensively studied. However, PAN has never before been generated by a scalable VP 3D-printing method, such as the state-of-the-art continuous liquid interface production (CLIP) process. Directly 3D printing PAN lattices via VP of a resin containing acrylonitrile (AN) monomer is challenging because PAN is a linear polymer insoluble in its own AN monomer. This linear polymer characteristic means that during VP 3D-printing, PAN undergoes precipitation reactions to form powder instead of forming a crosslinked network to maintain high-resolution architected shapes during photo-initiated polymerization.

[0125] Therefore, pioneering a new approach for incorporating PAN into 3D-printed high-resolution lattice structures via CLIP that bypasses the issues mentioned above followed by pyrolysis presents the potential for revolutionary high impact in sustainable applications ranging from batteries for energy storage to electrocatalysis for carbon capture and electromagnetic components for electrifying thermochemical reactors. B. Description

[0126] To overcome the challenges faced by VP 3D-printing high-resolution PAN structures for pyrolysis, we have developed a novel method for producing 3D carbon fiber structures from PAN that involves the following sequential steps: (1 ) 3D printing a lattice sacrificial scaffold structure out of a crosslinked gel material, for example polyethylene glycol) diacrylate (PEGDA), via CLIP, (2) infusing the gel scaffold structure with acrylonitrile monomers and a thermal initiator, (3) polymerizing the AN monomers to PAN linear chains inside the gel scaffold structure forming an interpenetrating polymer network, and then (4) subjecting the PAN-infused gel lattice structure to thermal treatment processes (e.g., an oxidative pre-treatment, isothermal holds, and / or pyrolysis) that converts the PAN to 3D pyrolytic carbon.

[0127] We have demonstrated the ability to infuse AN monomer solution into PEGDA 3D printed structures. We heat these AN-infused 3D printed structures to induce the free radical polymerization of AN to form PAN in situ. We then subsequently pyrolyze these PAN-infused PEGDA composite structures to form pyrolytic carbon-based structures. We have used this process to generate PAN-infused PEGDA lattices that maintain their 3D lattice shape and undergo isotropic shrinkage during pyrolysis. We have verified that AN is indeed polymerized to form PAN inside the PEGDA lattice gel scaffold via attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. In FTIR spectra, we observe the intensity of the nitrile band, a characteristic peak of PAN that is not present in PEGDA, increasing over time during polymerization. To date, we have varied the pyrolysis conditions of these PAN-swollen PEGDA templates over a wide range of temperatures and excipient gas (air, nitrogen) flow rates towards maximizing the outputted pyrolytic carbon char yield, which has reached up to 40% by mass, comparable to industry values of char yield for conventionally electrospun PAN fibers. The resulting pyrolytic carbon lattice structure has a rough surface texture, contributing further to the high surface area of the final material. Preliminary electrochemical testing of the resulting pyrolytic carbon structures has demonstrated that they are electrically conductive and they exhibit acceptable voltage potential ranges for energy storage. This novel VP 3D-printing and gel infusion method can be used to pioneer the incorporation of other linear polymers beyond PAN into high-resolution lattice structures, for example polyethylene and polyimides. PAN-based pyrolytic carbon lattice structures developed via our novel gel infusion method hold significant promise for use in commercial applications ranging from electrodes in battery energy storage to susceptors for electrifying thermochemical reactors to substrates in electrocatalysis for carbon capture. In the battery field, we have discussed using this method for production of flowdirecting electrodes in redox flow batteries, zinc-aqueous batteries, and lithium sulfur batteries. These battery systems could be used in grid energy storage or in electrical vehicles (EVs). We can also use this method to produce susceptors for thermochemical reactors in high-throughput reactions such as the reverse water gas shift (RWGS) reaction, an endothermic chemical process that is anticipated to be foundational to a modern sustainable industrial economy.

[0128] These applications are viable because pyrolyzing polyacrylonitrile-based 3D structures generated via our gel infusion method yields carbonaceous material with excellent electrical conductivity and strong chemical stability. Using CLIP vat polymerization 3D-printing to generate these structures enables complex 3D geometries with high surface area to volume ratios, for example tailored lattices. Specifically, these structures are designed to achieve high volumetric-density electrochemically active surface area and facilitate mass transport.

[0129] The differentiation of this work is that acrylonitrile has never been swelled in a 3D-printed gel structure and subsequently polymerized to polyacrylonitrile. We have demonstrated that this process, when followed by pyrolysis, can be used to generate revolutionary 3D lattice carbon fiber structures. The only competing instance of PAN VP to date has been via a recent small-scale preliminary interfacial photopolymerization method, which has trouble generating shapes more than a few layers thick. Our PAN- based 3D carbon fiber production procedure entails gel resin fabrication, 3D printing a gel scaffold via CLIP, polymerization of AN to PAN while swelled in the gel, and subsequent pyrolysis. Similar gel infusion methods have enabled metal lattice production, and PAN has been infused in polymer systems to make interpenetrating networks. However, to our knowledge, the combination of these approaches is novel, and neither of the strategies have been used to generate precursors for pyrolysis for the applications we have described herein.

[0130] We have reviewed the existing pyrolysis and vat polymerization 3 D-printing literature, and this elucidated numerous commercial and custom photopolymerizable resins that have been employed towards energy storage, electrocatalysis, and adsorption applications. However, one significant shortcoming of existing work is that the commercial resins often used in these studies, such as acrylate-based Autodesk PR-48 and epoxy-based EPON SU-8, were not originally designed for pyrolysis. Therefore, they inherently do not have the most optimal polymeric composition for tailoring pyrolysis char yield output. Several custom polymer resins have been developed with the goal of being more intentional about which polymer components are being incorporated into the pyrolyzed structure, for example incorporating graphene oxide into polyethylene glycol) diacrylate (PEGDA) or generating aromatic polyimide structures among other formulations. While some of these tailored custom resins show some promise, they usually require scanning stereolithography or two photon lithography approaches, which are not scalable, and they often fall short in conductivity characteristics and structural integrity when compared to industry standard traditional pyrolytic carbon precursors that are used outside of the 3D-printing field.

[0131] Example 2 - Holistic manufacturing of 3D architected electrodes for high volumetric electrochemical reactions for energy sustainability

[0132] A. Introduction

[0133] The increasing global demand for renewable energy, driven by ever-growing energy needs and the depletion of fossil fuel resources, which is further exacerbated by recent geopolitical crises, has driven an imperative need for energy storage systems capable of harnessing and storing massive intermittent natural energy sources like sunlight and wind. The growing demand for affordable, long-range electric transportation has spurred the demand for energy storage systems capable of delivering high-energy density under rapid charging and discharging, i.e., high power density. Meeting these demands call for structural engineering of electrodes that can accommodate a substantial amount of active materials (i.e., redox centers) and allow every part of these active materials to timely participate in energy conversion.

[0134] Nearly 7% of CO2 emissions come from the production of industrial chemicals. Electrochemical synthesis possesses great promise to utilize renewable energy sources for conversion of abundant feedstocks, like green H2derived from solar water splitting, and subsequently the formation of NH3and CH3OH by reaction of H2with N2and CO2respectively. Employing appropriately tailored 3D electrodes anchored with active materials (i.e., catalytically active sites) for the synthesis of these foundational compounds, will enable the concurrent occurrence of electrochemical reactions in all three Cartesian dimensions for highly efficient and low-cost industrial-scale production.

[0135] The following describes a holistic manufacturing process for the fabrication of 3D carbon-based electrodes that will empower high-volumetric capacities and rapid occurrence electrochemical reactions, a capability hitherto unattainable. This innovative approach capitalizes on the unique advantages of new additive manufacturing techniques — 3D printing of polymeric structure — and catalyst-assisted graphitization and 1 D nanocarbon growth to produce highly electrically conductive and mechanically robust 3D electrodes with geometries customized for specific applications. Such a process capability harbors immense potential to reshape the future of energy storage and electrocatalysis / chemical production, poised to underpin the development of environmentally friendly and high efficiency systems critical for a sustainable future.

[0136] B. Discussion

[0137] These electrodes consist of continuous microchannels defined by polymer templates, which will be transformed to metal and carbon composite materials through pyrolysis, establishing a primary structure. High-density carbon nanotubes / carbon nanofibers (CNTs / CNFs) are grown on the primary structure via catalyst-assisted 1 D nanocarbon growth, forming a secondary structure. A thin layer of active materials is conformally electro-grafted onto the secondary structure, creating a tertiary structure. FIG. 4 depicts steps for generating a conductive pyrolytic carbon microstructure having incorporated active material according to certain embodiments. FIG. 4 depicts the proposed fabrication process and highlights the high-resolution printing of complex structures and hierarchical structuring as described above.

[0138] In some embodiments, the 3D hierarchical electrode structures (FIG. 4) encompass three key salient features. First, 3D printed polymeric structures will be first infused with a carbohydrate such as sucrose, fructose, ribose, glucose, xylose, starch, etc., either in and aqueous solution prior to a solvothermal carbonization step, or simultaneously during the solvothermal step itself. If a gel-like polymer template, such as PEGDA, is infused with the carbohydrate in an aqueous solution it is subsequently carbonized via a solvothermal process to generate a carbonaceous hydrochar that assumes the shape of the gel-like polymer template. In this solvothermal step the solvent used may be both a bad solvent for sugar and is immiscible with water to prevent leaching of infused materials. If the polymer template is comprised of a rigid polymer structure, the dehydrated precursor derivatives will react with available vinyl groups to form highly aromatic moieties via a Diels-Alder cycloaddition reaction, offering a high carbonization yield, such as in the example reaction below:

[0139] FIG. 5 depicts hierarchal three-dimensional structure of a conductive pyrolytic carbon microstructure according to certain embodiments. A graded strut structure in the 3D printed polymer template will result in a higher density of 1 D nanocarbons near the separator interface, thereby reducing ion diffusion length. In some instances, metal species are simultaneously incorporated during carbohydrate impingement.

[0140] Upon pyrolysis, primary structures of 3D intricate metal / carbon composite microarchitectures are formed. Our choice of which specific metal ions to infuse into the polymer matrix prior to pyrolysis is made with the goal of providing one or more of: (1 ) increase graphitic carbon yield by forming multiple metal-ligand coordination bonds between the polymer repeat units, (2) promote polymer graphitization, (3) serve as a catalyst for subsequent formation of secondary structures, and (4) enhance the electrical conductivity and mechanical integrity of the resultant 3D electrodes. The primary electrode structure offers the continuous microchannels to deliver carbon gas precursors for subsequent 1 D nanocarbon growth. These microchannels are the main conduits required for mass diffusion during electrochemical reactions and, as such, they should possess excellent electrical conductivity and mechanical integrity. Second, by harnessing the metal species already present on the surface of the primary structure, CNTs / CNFs are grown on these surfaces. The resulting secondary structure of high- density nanochannels offer significantly increased surface areas with low tortuosity, substantially enhancing the loading of active materials and electrical conductivity while minimizing dead void volume. Third, electrografting active materials onto the secondary structure ensures uniform coverage across the entire topological surface, forming the tertiary structure. This is in stark contrast to electrografting onto nanopores, which planarizes the surface, thus drastically reducing available surface area.

[0141] In certain embodiments, the optimization of a 3D pyrolytic carbon microstructure faces challenges, including inadequate electrical conductivity and low mechanical integrity. Addressing these issues and to increase graphitization char yield, in some cases transition metal ions are infused and deposited ions into a 3D polymeric substrate that can coordinate with ligands on polymers (e.g., Fe3+«-> OOC). To achieve a combination of high graphitic carbon conversion, excellent electrical conductivity, and robust structural integrity, transition metal species are integrated within 3D polymeric structures prior to carbonization. The multifaceted functionalities of these metals are outlined as follows: (i) Establishing coordination bonds. The establishment of coordination bonds is a crucial aspect in the realm of transition metal ions, particularly those with empty d-orbitals, such as Fe(lll), Cu(ll), and Ni(ll). These ions have the capacity to form coordination bonds with either lone pair electrons on oxygen (associated with acrylic groups) or nitrogen (associated with pyridinic groups) within the polymer structure, (ii) Catalyzing graphitization. Catalyzing graphitization will be facilitated by transition metals, enabling graphitization happening at lower temperature range, such as 700°C instead of 1000°C. This catalytic transformation plays a vital role in converting decomposed products into carbon, thereby enhancing the overall polymer- to-carbon conversion, (iii) Growing CNT / CNF on primary structure. The reduced metal species on primary structure can not only capture the providing carbon source gas for CNT growth (ethylene) but also the degradation gas generated during pyrolysis, increasing volumetric area significantly, (iv) Augmenting electrical conductivity and mechanical integrity. Good conductivity comes from graphitic carbon and metal. Thus, the inclusion of a significant quantity of metal within the primary structure can significantly improve the electrical conductivity and mechanical integrity, elongating the durability for usage in practical application.

[0142] In a procedural approach, polymeric substrates undergo initial soaking in solvent such as ethanol with specific metal precursors, such as FeCIs, NiCL and CuCh, followed by sonication at high temperature to promote metal species infusion (60°C for 12 hours for example) into the highly crosslinked polymer structure. Subsequently, a solvothermal method involves placing the polymeric substrate in a well-sealed vial (a 20 mL ethanol solution with specific metal precursors at 160°C for 12 hours as an example). The elevated pressure and temperature conditions aid in metal ion incorporation through increasing the solubility of polymer and metal in the solution and accelerating coordination bond formation between metal ions and reactive groups on polymer chains.

[0143] The amount of metal species that can be incorporated by the infusion method is limited due to the high-crosslinking nature of polymer structure. Augmenting metal deposition onto the 3D polymeric substrate is deemed advantageous for improving mechanical performance, mitigating large polymer shrinkage during pyrolysis while offering excellent electrical conductivity. One approach is called “leaky solvothermal approach”. In this case, the polymeric substrate is placed in a non-totally sealed solvothermal vial (a 20 mL ethanol solution with specific metal precursors at 160°C for 1 .5 hours as an example). Evaporation of solvent during the process concentrates metal species, gradually precipitating onto the surface of polymeric surfaces. The solvothermal time needed to be carefully controlled, if the time is too long and all the solvent is completely dry, the nonuniform precipitation of metal salts may damage the fragile 3D polymeric substrate, if the time is too short then there will not be enough metal salt deposition on the polymeric substrate. Alternatively, a repeated process involves casting ethanol solution with a specific metal precursor on the polymeric template, allowing it to dry, and repeating the cycle. The sample will be flipped for uniform deposition. A NIR lamp can be used to accelerate the drying process. The success of the aforementioned technologies hinges upon the manufacturing 3D architected electrodes where structural features can be precisely engineered to optimize volumetric capacity. Intensive research has demonstrated the great promise of 3D architected electrodes. Indeed, increasing electrode thickness has resulted in an enhancement of energy density, exemplified by an increase from 240 Wh / kg to 350 Wh / kg using a thicker electrode. However, this enhancement has come at the cost of rate capability (i.e., power density) as well as the underutilization of active materials. This primarily stems from ill-defined electrode structures that impede the participation of active materials, either located in deeper spaces or trapped within difficult-to-access pores, in electrochemical reactions. To achieve significantly improved volumetric capacity at a high rate, it is essential to maximize the available surface area for hosting active materials and simultaneously minimizing tortuosity for facile mass transport. Further, such highly porous electrodes must provide minimal “dead void” volume while maintaining excellent structural integrity throughout down-stream fabrication and extended operation. Meeting this set of rigorous electrode requirements demands the establishment of a 3D electrode fabrication process that can reproducibly produce intricate micro- and nano-structures with high precision and tunability. The establishment of such a capability is pivotal in bridging the knowledge gap concerning how the geometric arrangement of a 3D electrode determines its volumetric capacity and rate capability.

[0144] Carbon is a lightweight and low cost, high abundance material. Graphitized 3D carbon-based structures that offer high electrical conductivity and good chemical stability, have demonstrated great potential as 3D electrodes. Due to good adhesion of active materials to carbon, either intrinsically or bestowed by surface functionalization, they can be monolithically integrated on carbon surfaces. The new 3D hierarchical carbon-based electrodes, designed with a proper spatial geometrical arrangement at the micro- and nanoscale for maximal loading and accessibility of active materials, will offer high volumetric-density electrochemical reactions in a timely manner.

[0145] A holistic manufacturing process for an architected carbon-based 3D electrode, loaded with the maximum loading of active materials (redox centers or electrocatalysts) lays a solid foundation for achieving remarkable volumetric capacity. 3D electrodes which can significantly improve the performance of existing technologies, such as batteries and fuel cells, will be enabled at reduced costs by eliminating inactive components and binders common in current electrochemical energy storage systems. The new 3D electrode platform also will unlock new possibilities for applications that can drive the technologies needed for a more sustainable chemical manufacturing industry. Further, while the resin-based 3D printing process produces small amounts of organic waste, this waste can be easily cured prior to disposal, eliminating its toxicity, and allowing it to be disposed of as a common plastic. Additionally, the subsequent carbon conversion process relies on minimal quantities of environmentally friendly chemicals, which can be recycled. This cost-effective and environmentally responsible approach to manufacturing high-performance 3D architected electrodes potentially represents a significant stride toward enabling green fabrication and green technology. The methods described herein provide for low cost, green and scalable production and can be tailored for specific applications.

[0146] Table 1 summarizes lattice samples for conductive pyrolytic carbon microstructures according to certain embodiments. Lattice samples prepared by a solvothermal carbonization process having different amounts of carbohydrate (e.g., glucose 2 grams, 1 .5 grams and 1 gram) are summarized. Pyrolysis parameters include temperature, temperature ramp rate and gaseous environment (e.g., under reducing gas H2) are also included. Post-pyrolysis yield ranged from 5.54% to 56.9% depending on the amount of carbohydrate present and pyrolysis parameters.

[0147] Table 1 - Lattice Samples for Conductive Pyrolytic Carbon Microstructures

[0148] FIG. 6 depicts a comparison of strut diameter before and after solvothermal process according to certain embodiments. In particular, lattice structures with 2 grams of glucose having 300 micron struts exhibited greater than 27% mass gain after solvothermal process having a linear expansion of at least 20%. FIG. 7 depicts a comparison of physical characteristics of lattice structures of polyethylene glycol) diacrylate (PEGDA) after different durations and conditions for solvothermal carbonization according to certain embodiments. Lattice structures of poly(ethylene glycol) diacrylate (PEGDA) soaked in a saturated carbohydrate (glucose) solution that is: 1 ) spun in a spinner prior to solvothermal carbonization at 190 °C for 5 hours; and 2) solvothermal carbonization at 190 °C for 13 hours without prior spinning.

[0149] Example 3 - Lattice Geometry and Pyrolysis

[0150] The effect of pyrolysis on lattice unit cell geometry was determined. Pyrolysis was conducted at 800 °C on tetrahedral and Voronoi geometries using commercial PR 48 resins to determine the effect of pyrolysis on geometry. The samples tested have 300 pm strut diameters pre-pyrolysis with a carbon printer with 75-micron pixels. Initial thermogravimetric analysis (TGA) tests revealed that PR48 undergoes the bulk of its mass loss decomposition at 400 °C before arriving at complete carbonization at 650 °C. Therefore, a furnace pyrolysis procedure was chosen involving a 5°C per minute ramp from 25 °C to 400 °C, a 2 hour isothermal hold at 400°C to facilitate carbonization and allow volatile components to escape, and then a 5 °C per minute ramp to 800 °C with a final 2 hour hold at 800°C to generate final pyrolytic carbon material.

[0151] These initial pyrolysis tests demonstrated that tailored lattice features printed via CLIP remain intact and shrink by up to 70% by volume after conversion to pyrolytic carbon during pyrolysis. The isotropic shrinkage and resulting structural integrity of a tetrahedral lattice disk with a high density (1-3 mm unit cells) of 150-300 pm diameter struts proved the viability for using these methods to develop high void fraction pyrolytic carbon samples. The PR48 char yields were measured in the range of 4 - 6.5% by mass after pyrolysis following the furnace procedure outlined above. Modifying the furnace procedure significantly affected the char yield, with the greatest PR48 char yield of 12.3% being achieved via a run that had a 1 -hour isothermal hold at 200°C in air instead of the 2-hour hold at 400°C in N2, but even 12.3% is low compared to pyrolysis industry standard char yields that reach greater than 40%.

[0152] FIG. 8 depicts pyrolysis shrinkage behavior of different lattice unit cell geometries of polymeric microstructures according to certain embodiments. Tetrahedral lattice unit cell geometries exhibited a 5.4% char yield and the Voronoi 4.7% char yield. The samples are inserted into a furnace and heated as described above. The tetrahedral lattice experienced less warping and collapse while also experiencing a higher char yield than Voronoi (FIG. 8), indicating that stretching-dominated structures with greater loadbearing capabilities can be more easily pyrolyzed isotopically. The unit cell morphology analysis found that polymeric microstructures having a tetrahedral lattice unit geometry exhibited more stretching dominated unit cell morphology and Voronoi exhibited more bending dominated unit cell morphology. The Voronoi lattices collapse more than tetrahedral lattices. In some instances, stretching-dominated structures are more weight efficient for load bearing and isotropic shrinkage. Stretching-dominated geometries were more effective for isotropic shrinkage and less distortion. Char yield was low compared to general standard char yields of 40%-60%. FIG. 8 depicts optical micrographs of PR48 polymer lattices before pyrolysis and after pyrolysis. FIG. 8 also provides macroscopic images of tetrahedral lattice disk, comparing tetrahedral and Voronoi lattice shrinkage behaviors. Example 4 - Methods for Producing Polyacrylonitrile (PAN)-infused Pyrolyzed Microstructure having Three-Dimensional Lattices

[0153] Polyacrylonitrile (PAN) can be used to generate carbon fibers having high electrical conductivity and high surface area-to-volume. PAN is incorporated into polymeric lattices through gel infusion as described above. In some instances, acrylonitrile (AN) is swelled in the 3D polymeric lattice gel structure such as in a polyethylene glycol) diacrylate (PEGDA) scaffold. In some instances, the polymeric lattice serves as a sacrificial scaffold for PAN polymerization into 3D lattices that isotropically shrink down to intertwined carbon fiber structures during pyrolysis. FIG. 9 depicts generating pyrolyzed polyacrylonitrile (PAN) three-dimensional lattices according to certain embodiments. The polyacrylonitrile precursor component is composed of linear PAN polymeric units and cyclization stabilization occurs at elevated temperatures (e.g., 200-300 °C) under an oxidative atmosphere. FIG. 9 depicts the physical characteristics of: 1 ) a pristine lattice; 2) a pressurized lattice; 3) a stabilized lattice; 4) a carbonized lattice; and 5) an activated lattice. The pristine lattice is prestabilized at 140 °C and stabilized at 200 °C. Carbonization is conducted at 1000 °C and activated at 900 °C.

[0154] FIG. 10 depicts polyacrylonitrile (PAN) gel infusion in a polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments. A PEGDA polymeric microstructure is generated as described above (e.g., by CLIP) and infused with acrylonitrile monomer and radical initiator in dimethylsulfoxide (DMSO) solvent. The resin formulation includes 30 wt% PEGDA, 1 wt% trimethylbenzoyldiphenyl phosphine oxide (TPO) photoinitiator and 0.5 wt% tartrazine UV blocker in DMSO. The scaffold was generated with a CLIP system tuned to have 30-micron pixel resolution and a build area of 76 mm by 48mm.

[0155] In some instances, the PEGDA lattice gels are swelled with 1 wt% azobisisobutyronitrile (AIBN) thermal initiator and various wt% amounts of AN in DMSO (up to 100 wt% pure AN). Afterwards, the AN-swelled gels are immersed into a heating medium solution that allows the transfer of heat into the scaffold. Polymerization of AN inside the swelled PEGDA lattices is then conducted at 60 °C for 28 hours. The heating mediums tested include mineral oil, DMSO, argon gas, and Fluorinert FC-40, with the greatest challenge being determining a medium that both mitigates AN’s tendency to evaporate due to its 77°C boiling point and prevents acrylonitrile from diffusing out of the swelled PEGDA gel. The swelled samples that use DMSO solvent have resulted in the best preservation of the high-resolution 150-300pm lattice strut features with pyrolysis char yields of 31% whereas the pure AN swelled samples have generated the highest char yields of up to 46% by mass but do not resolve features as finely.

[0156] In some instances, the precursor composition is swelled into the scaffold and heated (e.g., to 70 °C) to polymerize the polyacrylonitrile to form a PEGDA scaffold with interpenetrating PAN network. Oxidative treatment of the polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold is conducted at 200-300 °C followed by an isothermal hold under nitrogen atmosphere at 350-425 °C. The scaffold is pyrolyzed at or above 800 °C to generate the three-dimensional pyrolytic carbon lattice.

[0157] FIG. 1 1 depicts the changes in physical characteristics of polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold during the polymerization and pyrolysis process according to certain embodiments. As shown in the polyethylene glycol) diacrylate scaffold exhibits a yellow color which slightly lightens after the PEGDA scaffold is swelled with the composition of acrylonitrile in dimethyl sulfoxide. The swelling composition in some instances includes 30 wt% acrylonitrile and 1 wt% azobisisobutyronitrile (AIBN) radical initiator in dimethyl sulfoxide. After polymerizing the polyacrylonitrile, the scaffold begins to exhibit a light brown color. Polyacrylonitrile polymerization in some instances can take greater than 24 hours when infused into the PEGDA scaffold. The PAN-infused PEGDA has a 28% mass increase compared to pristine a PEGDA scaffold (exhibiting a 10-to-3 PEGDA to PAN ration by weight). Pyrolysis of the polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) shrinks and turns the scaffold to a black color.

[0158] A detailed study of pyrolysis furnace conditions to elucidate the relationship that various treatments have on resulting material properties including char yield, mechanical integrity, surface morphology, and electrochemical behavior was conducted. PAN is typically subjected to a heating procedure that entails an initial heating step in an oxygen-containing atmosphere up to 200-300°C for PAN chain stabilization followed by a second step heating in an inert environment up to 800-1600 °C where the PAN chains are converted to cyclic six-membered rings. In some embodiments, the PAN infused PEGDA octet lattice structures have pyrolyzed isotopically following this strategy during initial pyrolysis runs. During initial studies into the effects of furnace conditions on pyrolysis output, PAN infused PEGDA was subjected to various heating profiles through TGA to analyze resulting char yields after different thermal treatments. Keeping ramp rate constant at 5°C / min for all steps, the effect that oxidative hold temperatures have on resulting char yield was analyzed. The TGA results (as discussed below) revealed that inclusion of an oxidative treatment versus no oxidative step enhances the char yield of the resulting material (37% without versus 41 -43% with an oxidative hold) despite being in the furnace at high temperatures for an additional hour. However, the temperature of the oxidative hold between 200°C to 300°C did not have a drastic impact (all within 41 - 43% final char yield).

[0159] FIG. 12 depicts a comparison of pyrolyzed polyethylene glycol) diacrylate (PEGDA) scaffolds and pyrolyzed polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffolds according to certain embodiments. Pyrolysis of a control PEGDA scaffold and the PAN-infused PEGDA scaffold was conducted with a 1 hour hold at 200 °C in air followed by a hold at 400 °C under nitrogen. The temperature was increased (ramping rate) at about 5 °C per minute. Pyrolysis was completed with a 2 hour hold at 800 °C under nitrogen. The PEGDA control scaffold exhibits a stretching- dominated octet lattice. Pyrolysis of the PEGDA scaffold generates a less than 5% char yield. On the other hand, the PAN-infused PEGDA scaffold exhibited a 31% char-yield.

[0160] The polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold and pyrolyzed carbonized microstructure was characterized by spectroscopy (attenuated total reflectance (ATR)-Fourier transform infrared (FTIR)), microscopy (scanning electron microscopy), electrochemical characterization and thermogravimetric analysis (TGA). FIG. 13 depicts ATR-FTIR spectroscopy of a polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments. Fourier Transform Infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode was used to verify the polymerization of PAN in the PEGDA scaffolds via evidence of a characteristic nitrile band at -2245 cm-1increasing over time in the PEGDA samples that have been undergoing polymerization. The relative unit of the nitrile band shows a large increase between 6 hours and 12 hours. In some instances, the polymerization is complete past 24 hours with less prominent increase in the nitrile band from 18 hours to 24 hours. The FTIR confirms polymerization of the polyacrylonitrile infused in the polyethylene glycol) diacrylate (PEGDA) scaffold. Also, during the reaction there is a visible color transition from the yellow AN-swelled PEGDA lattices turning to a light brown color after polymerization to PAN.

[0161] FIG. 14 depicts thermogravimetric analysis (TGA) of polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate char yields from pyrolysis after oxidative isothermal holds according to certain embodiments. The PAN-PEGDA char yields after various oxidative isothermal holds were analyzed by TGA. In some instances, the oxidative holds during pyrolysis can have structural integrity effects on the carbonized microstructure. In some instances, oxidative treatment runs were conducted under an air atmosphere at 200 °C, at 220 °C, at 240 °C, at 260 °C, at 280 °C and at 300 °C. Isothermal holds were conducted under nitrogen (N2) at 300 °C, at 350 °C, at 400 °C, at 450 °C, at 500 °C, at 600 °C, at 700 °C, at 800 °C and at 900 °C. Each isothermal hold was maintained for 1 hour. As depicted in FIG. 14, the char yields ranged from 37.2% when no oxidative isothermal hold was performed and up to 43.4% with an oxidative hold at 260 °C. Pyrolysis of PAN-infused PEGDA yields a high 30-40% char yield. Oxidative pre-treatment of the PAN-infused PEGDA in some instances improves pyrolytic char yield.

[0162] FIG. 15 depicts surface morphology of a pyrolyzed polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold by scanning electron microscopy according to certain embodiments. The struts of the SEM image shows that the pyrolyzed surface of the PAN-PEGDA scaffold has a rough surface. In some instances, the rough surface provides for a high surface area.

[0163] FIG. 16 depicts cyclic voltammetry for a pyrolyzed polyacrylonitrile (PAN) gel infused polyethylene glycol) diacrylate (PEGDA) scaffold according to certain embodiments. Electrochemical characterization of the pyrolyzed PAN-PEGDA scaffold was conducted in an electrochemical cell (FIG. 16, left panel) and a cyclic voltammetry plot (FIG. 16, right panel) was recorded at different scan rates showing a 0 to 0.6 V non- faradaic charge storage potential range. These plots demonstrate that the pyrolytic microstructures facilitate electric current and are therefore conductive.

[0164] In conclusion, PAN can be swelled in PEGDA and polymerized to form an interpenetrating network. Further testing demonstrated the method for PAN gel infusion into CLIP-generated PEGDA lattices exhibited high char yields of over 30 - 40% as compared to the significantly lower 4 - 12% yields observed for commercial PR48 resin. Additionally, initial TGA characterization of furnace conditions reveals that oxidative isothermal holds improve the char yields of both the PAN and PR48 samples. The above also demonstrated that lattice geometry can affect shrinkage behavior during pyrolysis, with a stretching-dominated cell type proving to be desirable for structural integrity supporting isotropic shrinkage.

[0165] Notwithstanding the appended claims, the disclosure is also defined by the following clauses:

[0166] 1 . A method of making a conductive pyrolytic carbon microstructure, the method comprising: a) irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition comprising a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface; b) displacing the build elevator away from the build surface; c) irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second non-polymerized region in contact with the build surface; and d) repeating steps a)-c) in a manner sufficient to generate a polymeric microstructure; e) contacting the polymeric microstructure with a composition comprising a carbon precursor component; f) pyrolyzing the polymeric microstructure to generate a conductive pyrolytic carbon microstructure.

[0167] 2. The method according to clause 1 , wherein the carbon precursor component further comprises one or more metals.

[0168] 3. The method according to any one of clauses 1 -2, wherein the carbon precursor component comprises a reactive precursor.

[0169] 4. The method according to clause 3, wherein the reactive precursor is a carbohydrate selected from the group consisting of sucrose, fructose, ribose, glucose, xylose and starch; and the carbohydrate is simultaneously infused and carbonized in the polymeric microstructure via a solvothermal process; or the carbohydrate is infused into the polymeric microstructure in solution and then carbonized via a solvothermal step.

[0170] 5. The method according to any one of clauses 3-4, wherein the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to undergo a Diels- Alder reaction with vinyl groups positioned on the polymeric microstructure during solvothermal carbonization.

[0171] 6. The method according to any one of clauses 3-5, wherein the is contacted with the polymeric microstructure in a manner sufficient to generate one or more aromatic moieties via a Diels-Alder reaction on the polymeric microstructure during solvothermal carbonization.

[0172] 7. The method according to any one of clauses 2-6, wherein pyrolyzing the polymeric microstructure generates a conductive pyrolytic carbon microstructure metal composite.

[0173] 8. The method according to any one of clauses 1 -7, wherein the method further comprises incorporating carbon nanotubes, carbon nanofibers or a combination thereof into the conductive pyrolytic carbon microstructure.

[0174] 9. The method according to clause 8, wherein contacting the conductive pyrolytic carbon microstructure comprises forming a layer of carbon nanotubes, carbon nanofibers or combination thereof on a surface of the pyrolytic carbon microstructure. 10. The method according to clause 9, wherein the method further comprises contacting the conductive pyrolytic carbon microstructure with an active material.

[0175] 11 . The method according to clause 10, wherein the active material is electro-grafted to the conductive pyrolytic carbon microstructure.

[0176] 12. The method according to clause 11 , wherein the active material is electro-grafted to the layer of carbon nanotubes, carbon nanofibers or combination thereof on the surface of the pyrolytic carbon microstructure.

[0177] 13. The method according to any one of clauses 11 -12, wherein electro-grafting of the active material to the conductive pyrolytic carbon microstructure is sufficient to generate a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0178] 14. The method according to clause 1 , wherein the carbon precursor component comprises a polymeric precursor and the method comprises polymerizing the polymeric precursor to generate a non-conductive polymer within the polymeric microstructure.

[0179] 15. The method according to clause 14, wherein pyrolyzing the polymeric microstructure generates a pyrolytic carbon microstructure comprising a conductive pyrolytic carbon polymer positioned therein.

[0180] 16. The method according to clause 1 , wherein the polymeric precursor comprises acrylonitrile.

[0181] 17. The method according to clause 14, wherein the non-conductive polymer comprises polyacrylonitrile.

[0182] 18. The method according to any one of clauses 14-17, wherein the conductive pyrolytic carbon polymer comprises a conductive pyrolytic carbon lattice.

[0183] 19. The method according to clause 18, wherein the conductive pyrolytic carbon polymer comprises a conductive pyrolytic carbon three-dimensional (3D) lattice.

[0184] 20. The method according to any one of clauses 14-19, wherein the polymeric precursor further comprises a solvent.

[0185] 21 . The method according to claim 20, wherein the solvent comprises dimethyl sulfoxide. 22. The method according to any one of clauses 14-21 , wherein the method comprises contacting the polymeric microstructure with a polymeric precursor composition comprising: a radical initiator; and a solvent.

[0186] 23. The method according to clause 22, wherein the radical initiator comprises a thermal radical initiator.

[0187] 24. The method according to clause 23, wherein the radical initiator comprises a photo-initiator.

[0188] 25. The method according to any one of clauses 23-24, wherein the radical initiator comprises azobisisobutyronitrile (AIBN).

[0189] 26. The method according to any one of clauses 22-25, wherein the solvent comprises dimethylsulfoxide.

[0190] 27. The method according to any one of clauses 14-26, wherein the method comprises swelling the polymeric microstructure with the polymeric precursor.

[0191] 28. The method according to any one of clauses 14-27, wherein the method comprises applying heat to the polymeric microstructure with the polymeric precursor to polymerize the polymeric precursor into a non-conductive polymer positioned within the polymeric microstructure.

[0192] 29. The method according to clause 28, wherein the polymeric microstructure with the polymeric precursor is heated at a temperature of from 50 °C to 100 °C.

[0193] 30. The method according to clause 28, wherein the polymeric microstructure with the polymeric precursor is heated at a temperature of from 60 °C to 80 °C.

[0194] 31 . The method according to any one of clauses 28-30, wherein the polymeric precursor is polymerized within the polymeric microstructure in the presence of a heating medium.

[0195] 32. The method according to clause 31 , wherein the heating medium comprises one or more of mineral oil, dimethyl sulfoxide, argon gas and a fluorinated heat-transfer fluid.

[0196] 33. The method according to any one of clauses 14-32, wherein the method further comprises oxidative treatment of the polymeric microstructure with the non-conductive polymer positioned within. 34. The method according to clause 33, wherein the oxidative treatment comprises applying heat to the polymeric microstructure with the non-conductive polymer in the presence of oxygen.

[0197] 35. The method according to any one of clauses 33-34, wherein the oxidative treatment comprises heating at a temperature of from 150 °C to 350 °C.

[0198] 36. The method according to any one of clauses 33-34, wherein the oxidative treatment comprises heating at a temperature of from 200 °C to 300 °C.

[0199] 37. The method according to any one of clauses 33-36, wherein the method comprises an oxidative treatment for a duration of 20 minutes to 120 minutes.

[0200] 38. The method according to any one of clauses 14-37, wherein the method further comprises an isothermal hold of 30 minutes to 90 minutes after oxidative treatment.

[0201] 39. The method according to any one of clauses 14-38, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed by heating the polymeric microstructure comprising the non-conductive polymer under an inert atmosphere.

[0202] 40. The method according to clause 39, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed by heating the polymeric microstructure comprising the non-conductive polymer under vacuum.

[0203] 41 . The method according to clause 39, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed by heating the polymeric microstructure comprising the non-conductive polymer under an inert gas selected from nitrogen, argon, helium or a combination thereof.

[0204] 42. The method according to any one of clauses 14-41 , wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed by heating to a temperature of from 300 °C to 1600 °C.

[0205] 43. The method according to clause 42, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed by heating to a temperature of from 400 °C to 1000 °C.

[0206] 44. The method according to any one of clauses 39-43, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed for a duration of 2 hours or more. 45. The method according to any one of clauses 14-44, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 50% or less.

[0207] 46. The method according to any one of clauses 14-44, wherein the polymeric microstructure comprising the non-conductive polymer is pyrolyzed in a manner sufficient to reduce the size of the polymeric microstructure by 25% or less.

[0208] 47. The method according to any one of clauses 1 -46, wherein pyrolyzing the polymeric microstructure comprising the non-conductive polymer exhibits a char yield of 40% or more.

[0209] 48. The method according to any one of clauses 1 -46, wherein pyrolyzing the polymeric microstructure comprising the non-conductive polymer exhibits a char yield of 60% or more.

[0210] 49. The method according to any one of clauses 1 -48, wherein pyrolyzing the polymeric microstructure comprising the non-conductive polymer is sufficient to generate a pyrolytic carbon microstructure having a compressive strength that is 50% or greater as compared to the compressive strength of the polymeric microstructure.

[0211] 50. The method according to any one of clauses 1 -49, wherein the pyrolytic carbon microstructure exhibits a compressive strength that is 0.1 GPa or greater.

[0212] 51 . The method according to any one of clauses 1 -49, wherein the pyrolytic carbon microstructure exhibits a compressive strength that is 1 GPa or greater.

[0213] 52. The method according to any one of clauses 1 -51 , wherein the pyrolytic carbon microstructure comprises a lattice microstructure.

[0214] 53. The method according to clause 52, wherein the pyrolytic carbon microstructure comprises 2 or more repeating lattice cell units.

[0215] 54. The method according to any one of clauses 52-53, wherein the pyrolytic carbon microstructure comprises a gradient in the lattice cell units such that the density of lattice cell units increases across a longitudinal axis of the pyrolytic carbon microstructure.

[0216] 55. The method according to any one of clauses 52-54, wherein the lattice cell unit comprises a lattice shape selected from the group consisting of tetrahedral, Kagome, rhombic, icosahedral, Voronoi, octet, and triangular. 56. The method according to any one of clauses 52-55, wherein the pyrolytic carbon microstructure comprises lattice cell units having a size of from 25 pm to 1000 pm.

[0217] 57. The method according to any one of clauses 52-56, wherein the lattice microstructure comprises a plurality of struts.

[0218] 58. The method according to clause 57, wherein the lattice microstructure comprises struts having a thickness of from 5 pm to 150 pm.

[0219] 59. The method according to any one of clauses 1 -58, wherein pyrolytic carbon microstructure has a volume of from 0.01 pL to 2 pL.

[0220] 60. The method according to clause 59, wherein the pyrolytic carbon microstructure has a volume of 0.1 pL.

[0221] 61 . The method according to any one of clauses 1 -60, wherein the pyrolyzed structure composition comprises a polymerizable material selected from the group consisting of polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA), polyethylene glycol dimethacrylate (PEGDMA), polyarylacetylene, bisphenol A dicyanate, urethane acrylate, polycaprolactone, polyglycolic acid, polylactic acid, polylactic-co-glycolic acid, polyethylene glycol, thiol-enes, anhydrides, polyacrylic acid, polystyrene, divinylbenzene, poly(diaminonaphthalene), polyacrylonitrile, poly methylmethacrylate, ethoxylated pentaerythritol tetraacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyhexanediol diacrylate, polyvinyl alcohol, polyvinylpyrrolidone, vinyl carbonates, vinyl esters, acrylamides, hyaluronic acid, chitosan, collagen, gelatin, carboxymethylcellulose, and blends or copolymers thereof.

[0222] 62. The method according to clause 61 , wherein the polymerizable structure composition comprises polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA).

[0223] 63. The method according to clause 61 , wherein the polymerizable composition comprises a urethane acrylate.

[0224] 64. The method according to any one of clauses 1 -63, wherein the polymerizable composition is in contact with the build elevator and the build surface.

[0225] 65. The method according to clause 64, wherein the method comprises irradiating the polymerizable composition for a duration sufficient to bond the first polymerized region of the polymerizable composition to the build elevator. 66. The method according to any one of clauses 1 -65, wherein the build elevator is displaced in predetermined increments of from 0.5 pm to 1 .0 pm.

[0226] 67. The method according to clause 66, wherein the method further comprises adding polymerizable composition to the build surface after each displacement of the build elevator away from the build surface.

[0227] 68. The method according to any one of clauses 1 -67, wherein the polymerizable composition is irradiated through the build surface.

[0228] 69. The method according to any one of clauses 1 -68, wherein the polymerizable composition is irradiated in the presence of a polymerization inhibitor.

[0229] 70. The method according to any one of clauses 1 -69, wherein the polymerizable composition is continuously polymerized while displacing the build elevator away from the build surface.

[0230] 71 . The method according to any one of clauses 69-70, wherein the build surface is permeable to the polymerization inhibitor.

[0231] 72. The method according to clause 71 , wherein the polymerization inhibitor is oxygen.

[0232] 73. A conductive pyrolytic carbon microstructure comprising one or more conductive pyrolytic carbon components positioned therein.

[0233] 74. The conductive pyrolytic carbon microstructure according to clause 73, wherein the pyrolytic carbon microstructure comprises one or more metals.

[0234] 75. The conductive pyrolytic carbon microstructure according to any one of clauses 73-74, wherein the conductive pyrolytic carbon components positioned therein comprises carbonaceous solvothermal derivatives of a carbohydrate selected from the group consisting of sucrose, fructose, ribose, glucose, xylose and starch reacted with one or more vinyl groups positioned on the polymeric microstructure, via a Diels-Alder cycloaddition reaction.

[0235] 76. The conductive pyrolytic carbon microstructure according to any one of clauses 73-75, further comprising carbon nanotubes, carbon nanofibers or a combination thereof. 77. The conductive pyrolytic carbon microstructure according to clause 76, wherein the carbon nanotubes, carbon nanofibers or a combination thereof form a layer on a surface of the conductive pyrolytic carbon microstructure.

[0236] 78. The conductive pyrolytic carbon microstructure according to any one of clauses 75-76, further comprising an active material.

[0237] 79. The conductive pyrolytic carbon microstructure according to clause 78, wherein the active material is electro-grafted to the conductive pyrolytic carbon microstructure.

[0238] 80. The conduct pyrolytic carbon microstructure according to any one of clauses 78- 79, wherein the active material forms a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

[0239] 81 . The pyrolytic carbon microstructure according to clause 73, further comprising a conductive pyrolytic carbon polymer positioned within the pyrolytic carbon microstructure and wherein the conductive pyrolytic carbon polymer comprises a conductive pyrolytic carbon lattice.

[0240] 82. The pyrolytic carbon microstructure according to clause 81 , wherein the conductive pyrolytic carbon polymer comprises a conductive pyrolytic carbon three- dimensional (3D) lattice.

[0241] 83. The pyrolytic carbon microstructure according to any one of clauses 81 -82, wherein the conductive pyrolytic carbon polymer is formed from pyrolysis of a non- conductive polymer.

[0242] 84. The pyrolytic carbon microstructure according to clause 83, wherein the non- conductive polymer comprises polyacrylonitrile.

[0243] 85. The pyrolytic carbon microstructure according to any one of clauses 73-84, wherein the pyrolytic carbon microstructure comprises monolithic hard carbon.

[0244] 86. The pyrolytic carbon microstructure according to any one of clauses 73-85, wherein the pyrolytic carbon microstructure exhibits a compressive strength that is 0.1 GPa or greater.

[0245] 87. The pyrolytic carbon microstructure according to any one of clauses 73-86, wherein the pyrolytic carbon microstructure comprising the pyrolytic carbon polymer is electrically conductive. 88. The pyrolytic carbon microstructure according to any one of clauses 73-87, wherein the pyrolytic carbon microstructure comprises a lattice microstructure.

[0246] 89. The pyrolytic carbon microstructure according to clause 88, wherein the pyrolytic carbon microstructure comprises 2 or more repeating lattice cell units.

[0247] 90. The pyrolytic carbon microstructure according to any one of clauses 88-89, wherein the pyrolytic carbon microstructure comprises a gradient in the lattice cell units such that the density of lattice cell units increases across a longitudinal axis of the pyrolytic carbon microstructure.

[0248] 91 . The pyrolytic carbon microstructure according to any one of clauses 88-90, wherein the lattice cell unit comprises a lattice shape selected from the group consisting of tetrahedral, Kagome, rhombic, icosahedral, Voronoi, octet, and triangular.

[0249] 92. The pyrolytic carbon microstructure according to any one of clauses 88-91 , wherein the pyrolytic carbon microstructure comprises lattice cell units having a size of from 25 pm to 1000 pm.

[0250] 93. The pyrolytic carbon microstructure according to any one of clauses 88-92, wherein the lattice microstructure comprises a plurality of struts.

[0251] 94. The pyrolytic carbon microstructure according to clause 93, wherein the lattice microstructure comprises struts having a thickness of from 5 pm to 150 pm.

[0252] 95. The pyrolytic carbon microstructure according to any one of clauses 73-94, wherein pyrolytic carbon microstructure has a volume of from 0.01 pL to 2 pL.

[0253] 96. The pyrolytic carbon microstructure according to clause 95, wherein the pyrolytic carbon microstructure has a volume of 0.1 pL.

[0254] 97. The pyrolytic carbon microstructure according to any one of clauses 73-96, wherein the pyrolytic carbon microstructure comprises pyrolyzed polyethylene glycol) diacrylate (PEGDA), 1 ,6-hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA).

[0255] 98. A microelectrode comprising a conductive pyrolytic carbon microstructure comprising one or more conductive pyrolytic carbon components positioned therein.

[0256] 99. The microelectrode according to clause 98, further comprising a substrate.

[0257] 100. The microelectrode according to clause 99, wherein the substrate is planar.

[0258] 101. The microelectrode according to clause 99, wherein the substrate is non-planar. 102. The microelectrode according to any one of clauses 99-101 , wherein the substrate is conductive.

[0259] 103. The microelectrode according to clause 102, wherein the substrate is formed from a metal.

[0260] 104. The microelectrode according to clause 99, wherein the substrate is non- conductive.

[0261] Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

[0262] Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

[0263] The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims. In the claims, 35 U.S.C. §112(f) or 35 U.S.C. §112(6) is expressly defined as being invoked for a limitation in the claim only when the exact phrase "means for" or the exact phrase "step for" is recited at the beginning of such limitation in the claim; if such exact phrase is not used in a limitation in the claim, then 35 U.S.C. § 112 (f) or 35 U.S.C. §1 12(6) is not invoked.

Claims

What is claimed is:1 . A method of making a conductive pyrolytic carbon microstructure, the method comprising: a) irradiating a polymerizable composition positioned between a build elevator and a build surface to generate a polymerizable composition comprising a first polymerized region of the polymerizable composition in contact with the build elevator and a first non-polymerized region of the polymerizable composition in contact with the build surface; b) displacing the build elevator away from the build surface; c) irradiating the first non-polymerized region of the polymerizable composition to generate a second polymerized region of the polymerizable composition in contact with the first polymerized region and a second non-polymerized region in contact with the build surface; d) repeating steps a)-c) in a manner sufficient to generate a polymeric microstructure; e) contacting the polymeric microstructure with a composition comprising a carbon precursor component; and f) pyrolyzing the polymeric microstructure to generate a conductive pyrolytic carbon microstructure.

2. The method according to claim 1 , wherein the carbon precursor component further comprises one or more of: one or more metals; and a reactive precursor.

3. The method according to claim 2, wherein the reactive precursor is a carbohydrate selected from the group consisting of sucrose, fructose, ribose, glucose, xylose and starch; and the carbohydrate is simultaneously infused and carbonized in the polymeric microstructure via a solvothermal process; orthe carbohydrate is infused into the polymeric microstructure in solution and then carbonized via a solvothermal step.

4. The method according to claim 3, wherein the carbohydrate is contacted with the polymeric microstructure in a manner sufficient to: undergo a Diels-Alder reaction with vinyl groups positioned on the polymeric microstructure during solvothermal carbonization; or generate one or more aromatic moieties via a Diels-Alder reaction on the polymeric microstructure during solvothermal carbonization.

5. The method according to any one of claims 1 -4, wherein the method further comprises: incorporating carbon nanotubes, carbon nanofibers or a combination thereof into the conductive pyrolytic carbon microstructure; or forming a layer of carbon nanotubes, carbon nanofibers or combination thereof on a surface of the pyrolytic carbon microstructure.

6. The method according to claim 5 wherein the method further comprises: electro-grafting an active material to the conductive pyrolytic carbon microstructure; or electro-grafting an active material to the layer of carbon nanotubes, carbon nanofibers or combination thereof on the surface of the pyrolytic carbon microstructure.

7. The method according to claim 6, wherein electro-grafting of the active material to the conductive pyrolytic carbon microstructure is sufficient to generate a uniform coverage of the active material across a topological surface of the conductive pyrolytic carbon microstructure.

8. The method according to any one of claims 1 -7, wherein the carbon precursor component comprises a polymeric precursor and the method comprises polymerizingthe polymeric precursor to generate a non-conductive polymer within the polymeric microstructure; and wherein pyrolyzing the polymeric microstructure generates a pyrolytic carbon microstructure comprising a conductive pyrolytic carbon polymer positioned therein.

9. The method according to any one of claims 1 -8, wherein the method comprises swelling the polymeric microstructure with the polymeric precursor.

10. The method according to claim 9, wherein the method further comprises oxidative treatment of the polymeric microstructure with the non-conductive polymer positioned within by applying heat to the polymeric microstructure with the non- conductive polymer in the presence of oxygen.11 . The method according to any one of claims 1 -10, wherein pyrolyzing the polymeric microstructure comprising the non-conductive polymer exhibits a char yield of 40% or more.

12. The method according to any one of claims 1 -11 , wherein the polymerizable structure composition comprises polyethylene glycol) diacrylate (PEGDA), 1 ,6- hexanediol diacrylate (HDDA) or polyethylene glycol dimethacrylate (PEGDMA).

13. A conductive pyrolytic carbon microstructure comprising one or more conductive pyrolytic carbon components positioned therein.

14. The conductive pyrolytic carbon microstructure according to claim 13, wherein the pyrolytic carbon microstructure comprises one or more of: one or more metals; conductive pyrolytic carbon components positioned therein comprising carbonaceous solvothermal derivatives of a carbohydrate selected from the group consisting of sucrose, fructose, ribose, glucose, xylose and starch reacted with one ormore vinyl groups positioned on the polymeric microstructure, via a Diels-Alder cycloaddition reaction; a layer of carbon nanotubes, carbon nanofibers or a combination thereof formed on a surface of the conductive pyrolytic carbon microstructure; and an active material electro-grafted to the conductive pyrolytic carbon microstructure.

15. A microelectrode comprising a conductive pyrolytic carbon microstructure comprising one or more conductive pyrolytic carbon components positioned therein, wherein the pyrolytic carbon microstructure comprises one or more of: one or more metals; conductive pyrolytic carbon components positioned therein comprising carbonaceous solvothermal derivatives of a carbohydrate selected from the group consisting of sucrose, fructose, ribose, glucose, xylose and starch reacted with one or more vinyl groups positioned on the polymeric microstructure, via a Diels-Alder cycloaddition reaction; a layer of carbon nanotubes, carbon nanofibers or a combination thereof formed on a surface of the conductive pyrolytic carbon microstructure; and an active material electro-grafted to the conductive pyrolytic carbon microstructure.

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