Methods of additive manufacturing using atom transfer radical polymerization

Abstract

A method of additive manufacturing including co-extruding a first coreactive component and a second coreactive component to form a coreactive composition. The first coreactive component may include a catalyst and a ligand, and the second coreactive component may include a reducing agent. The first and second coreactive components may further include an initiator contained within one, or both of the first and second reactive components, an ethylenically unsaturated monomer contained within one, or both of the first and second coreactive components, and a rheology modifying filler contained within one, or both of the first and second coreactive components. The first and second coreactive components may react via atom transfer radical polymerization (ATRP).

Description

METHODS OF ADDITIVE MANUFACTURING USING ATOM TRANSFERRADICAL POLYMERIZATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 606,917 entitled “METHODS OF ADDITIVE MANUFACTURING USING ATOM TRANSFER RADICAL POLYMERIZATION”, filed on December 6, 2023, which is incorporated by reference in its entirety.GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with government support under Government Contract No. W911NF-17-2-0227 Additive Manufacturing (U.S. Army Research Laboratory, ARL). The government may have certain rights in the invention.FIELD

[0003] The present disclosure relates to methods of additive manufacturing and more specifically, to methods of additively manufacturing acrylics by atom transfer radical polymerization (ATRP).BACKGROUND

[0004] Additive manufacturing systems are used to print or otherwise build 3D parts from digital representations of the 3D parts (e.g., AMF and STL format files) using one or more additive manufacturing techniques. Examples of commercially available additive manufacturing techniques include extrusion-based techniques, jetting, selective laser sintering, powder / binder jetting, electron-beam melting, and stereolithographic processes. For each of these techniques, the digital representation of the 3D part is initially sliced into multiple horizontal layers. For each sliced layer, one or more tool paths are then generated, which provides instructions for the particular additive manufacturing system to print the given layer. 3D printed parts may be used for a wide variety of applications including prototyping and product development, aerospace parts, automotive parts, medical devices, architecture and construction, consumer goods, wearables, electronics, and tools.SUMMARY

[0005] The present disclosure provides a method of additive manufacturing. The method includes co-extruding a first coreactive component and a second coreactive component to form a coreactive composition. The first coreactive component includes a catalyst and a ligand, and the second coreactive component comprising a reducing agent. The first and second coreactive components further include: an initiator contained within one or both of the first and second reactive components; an ethylenically unsaturated monomer contained within one or both of the first and second coreactive components; and a rheology modifying filler contained within one or both of the first and second coreactive components. The first and second coreactive components react via atom transfer radical polymerization (ATRP).

[0006] The present disclosure further provides a coreactive composition. The coreactive composition includes a first coreactive component comprising a catalyst and a ligand; and a second coreactive component comprising a reducing agent. Either the first coreactive component, the second coreactive component, or both the first coreactive component and the second coreactive component further include: an initiator, an ethylenically unsaturated monomer, and a rheology modifying filler. The first coreactive component and second reactive component react via atom transfer radical polymerization (ATRP).BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 provides representative FT-IR spectra of gels from Example 7 taken after removal of sol. The spectra show the presence of intact isocyanate and anhydride functional groups in the cured materials.DETAILED DESCRIPTIONI. Definitions

[0008] For purposes of the following detailed description, it is to be understood that the disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0009] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0010] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0011] In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, in this application, the use of “or” means “and / or” unless specifically stated otherwise, even though “and / or” may be explicitly used in certain instances. Further, in this application, the use of “a” or “an” means “at least one” unless specifically stated otherwise. For example, “a” polymer, “a” pigment, “a” composition, “a” powder coating composition, “an” amphipathic material, “an” effect pigment, “a” polymeric resin particle, and the like refer to one or more of any of these items.II. Introduction

[0012] The present application provides methods of additively manufacturing articles using ambient reactive extrusion (ARE). ARE methods typically involve two separate coreactive components which are mixed and react to form a coreactive composition. Upon extrusion from an additive manufacturing device (e.g., a print nozzle) the coreactive composition cures under ambient conditions to form a three-dimensional structure.

[0013] Acrylic-based formulations are a common class of materials which may be used in a variety of three-dimensional printing methods. However, additive manufacturing of acrylics present challenges since acrylic compositions often require the use of peroxide photoinitiators which are sensitive to ambient oxygen and moisture. In addition, acrylic based formulations are less compatible with extrusion-type additive manufacturing because of their low viscosity.

[0014] To overcome these issues, the present disclosure provides a method for printing acrylic compositions that leverages atom transfer radical polymerization (ATRP), thus allowing for the formation of acrylics without the use of a peroxide initiator. Moreover, the present ARE compositions involve a rheology modifying filler which, in addition to the ATRP reaction, allows for facile printing of acrylic -based polymer compositions.III. Atom Transfer Radical Polymerization (ATRP) Chemistry

[0015] ATRP is a versatile and powerful technique that has improved the precision and control of polymer synthesis. ATRP is considered to be a successful controlled or “living” radical processes (CRPs).

[0016] A controlled radical polymerization (“CRP”) process is a process performed under controlled polymerization conditions with chain growth proceeding via a radical mechanism, such as, but not limited to, ATRP stable free radical polymerization, (“SFRP”) most frequently, nitroxide mediated polymerization, (“NMP”) reversible addition-fragmentation transfer, (“RAFT”), or degenerative transfer systems. A feature of CRP is the creation of an equilibrium between an active polymer chain and a dormant polymer chain. It may be preferable if a majority of polymer chains are present as dormant polymer chains. The equilibrium between the active and dormant chains typically provides for more controlled chain growth relative to conventional radical polymerization. CRP processes are capable of producing mere uniform polymers; however, the active propagating chain may react in termination reactions resulting in higher poly dispersities. Therefore, typically, to minimize termination reactions, the instantaneous concentration of active propagating species is maintained at a low concentration.

[0017] In CRP, the ability to maintain or adjust the equilibrium between active and dormant species and quantitative initiation early in the polymerization process allows, under appropriate conditions, the capability for synthesis of polymers with special architecture and functionality. In addition, if desired, the overall rate of monomer conversion may occur at rates equivalent to uncontrolled polymerization. A controlled polymerization process may be used to prepare polymers having a degree of polymerization that may be approximated from the ratio of the amount of consumed monomer to the initiator, a polydispersity close to a Poisson distribution and functionalized chain ends.

[0018] Typically, ATRP processes comprise a transition metal complex. The transition metal complex may participate in a repetitive redox reaction homolytically removing aradically transferable atom or group from an initiator molecule or dormant polymer chain, Pn— X, to form the active propagating species, P*n, and then deactivating active propagating species, P*n, by donating back a transferable atom or group (Scheme 1).Scheme 1. General mechanism for the ATRP processP«— X +

[0019] The transition metal catalyst for this repetitive addition process may be present, at least partially, in the lower oxidation state, or activator state, Mt" / Ligand. However, typically, the lower oxidation state of the transition metal catalyst is readily oxidized. Therefore, there are inherent difficulties in handling the catalyst associated with large scale bulk and solution-based polymerization processes and in emulsion and mini-emulsion processes where trace levels of oxygen should be removed. The typical ratio of activator (Mt" / Ligand) to deactivator (X-Mtn+1 / Ligand) varies with the specific monomers and the polarity of the reaction medium, as well as other factors, between 99 parts activator to 1 part deactivator to 5 parts activator to 95 parts deactivator.

[0020] A transition metal complex capable of maintaining the dynamic equilibrium and participate in a redox reaction comprising the transferable atom or group with the polymer chain may be used as the catalyst in ATRP. A suitable equilibrium can be formed after consideration of oxidation states, complex formation with suitable ligands and redox potential of the resulting complex to provide a catalyst for the desired (co)polymerization of a wide range of comonomers. A wide variety of ligands have been developed to prepare transition metal catalyst complexes that display differing solubility, stability and activity.

[0021] A. ATRP Initiation:

[0022] Typically, ATRP processes are initiated by the redox reaction between an initiator comprising one or more transferable atom(s) or group(s) and a catalyst complex comprising a transition metal salt in a lower oxidation state complexed with a ligand, solvent molecule, or monomer. The transferable atom or group is an atom or group that may be homolytically cleaved from the initiator by the catalyst, thereby oxidizing the catalyst to a higher oxidationstate and forming an active propagating species capable of monomer addition. After initiation, an ATRP process, generally, is based on a dynamic equilibrium between a transition metal complex reversibly activating and deactivating the polymer chain via a similar homolytic atom or group transfer via a redox reaction (Scheme 1). During the dynamic equilibrium the transition metal complex cycles between a lower oxidation state and a higher oxidation state.

[0023] The advantages of normal initiation of ATRP include that the added initiator molecule includes the transferable atom or group needed to initiate and subsequently repeatedly terminate each polymer chain, therefore no additional transferable atoms or groups are required to be added by other components of the polymerization process. Therefore, adding sufficient transition metal complex in the lower oxidation state provides suitable catalytic activity to the process. By “suitable catalytic activity” it is meant that the polymerization comprises an amount of catalyst needed to drive the reaction to a desired degree of polymerization with appropriate heat control to produce a polymer with the desired properties. Typically, an ATRP process requires a sufficient catalyst amount to compensate for any loss of catalytic activity due to termination reactions.

[0024] ATRP catalysts may vary in catalytic activity based upon the properties of the transition metal, the ligands and the temperature and polarity of the reaction medium, as well as other factors. Generally, more active catalysts are less oxidatively stable in their lower oxidation states. Due to this oxidative instability, active catalysts in their lower oxidation states are more difficult to handle; for instance, trace levels of oxygen or other oxidants should be to be removed from the polymerization medium prior to addition of the active catalyst in a lower oxidation state to prevent the catalyst from being converted to the higher oxidation state deactivator.

[0025] B. Reverse ATRP Initiation:

[0026] In a reverse ATRP, a more stable catalyst complex in the higher oxidation state may be added to the polymerization medium. Generally, the higher oxidation state of a transition metal complex is a lower cost and more oxidatively stable state of the complex and may often be stored in the presence of air.

[0027] In reverse ATRP, as opposed to normal ATRP, the transferable atom or group begins as a counterion or ligand on the transition metal salt or transition metal complex in the higher oxidation state. In “reverse ATRP,” the reaction is then initiated by generation of a radical by known processes, such as by decomposition of a standard free radical initiatorwhich either directly participates in a redox reaction with the higher oxidation state transition metal forming the transition metal complex in the lower oxidation state, and a molecule with a transferable atom suitable for initiation of an ATRP reaction, or it may initiate a polymerization that is quickly deactivated by the transition metal complex in the higher oxidation state. Typically, reverse ATRP processes require a high catalyst concentration in order to introduce the appropriate concentration of radically transferable atoms or groups to the reaction to both maintain a controlled polymerization and attain polymers of the desired molecular weight at high conversion of monomer to polymer.

[0028] In addition, a typical reverse ATRP process should be initiated in a narrow temperature range to ensure efficient thermal decomposition of the standard free radical initiator to reduce the catalyst complex and produce polymers with low poly dispersities. Further, since the first radicals are provided by normal radical initiators, it is not as easy to prepare homo-telechelic polymers, block, or graft copolymers of more complex architecture than with normal initiation.

[0029] C. SR&NI ATRP:

[0030] A SR&NI polymerization process comprises a dual initiation system for atom transfer radical polymerization. The initiation system comprises aspects of both standard free radical initiators and initiators comprising a transferable atom or group. The dual initiation system may be used to prepare any type of polymer that may be prepared by ATRP, such as, but not limited to, homopolymers, random, statistical, gradient, alternating copolymers, block, graft, branched or hyperbranched, star, comb, and bottle brush as well as other polymer structures.

[0031] However, polymerization in an SR&NI polymerization proceeds from two different initiators. In certain embodiments, this may be desirable. For example, if one initiator is a macroinitiator used to form a block copolymer in the “normal” initiated ATRP, but the conventional radical initiator added to form the active catalyst complex in a “reverse ATRP” will form a homopolymer that may be considered an undesirable byproduct for certain applications.

[0032] D. ATRP with Activators Regenerated by Electron Transfer (ARGET):

[0033] Activators regenerated by electron transfer (ARGET) is an optional modification of the previously described ATRP technique. ARGET- ATRP is designed to address limitations associated with traditional ATRP, particularly in terms of reducing catalyst concentration and improving control over the polymerization process.

[0034] In the traditional ATRP processes described above, the transition metal catalyst is used to mediate the equilibrium between dormant and active polymer chain ends. This equilibrium controls the polymerization process, allowing for fine tuning of molecular weight and end-group functionality. However, the presence of significant amounts of transition metal catalyst can have several drawbacks. Many of these catalysts are toxic and their residues in the final polymer products can be undesirable, especially for biomedical or other sensitive applications. Moreover, the presence of transition metal catalysts in the final articles can lead to coloration, affecting their optical properties. Removing residual metal catalysts from the finished polymer can be energy-intensive and time consuming.

[0035] ARGET-ATRP overcomes these issues by introducing a sacrificial reducing agent into the reaction system. This reducing agent continuously regenerates the active catalytic species in situ, while also maintaining the catalyst in a lower oxidation state, reducing its propensity to initiate side reactions. This is especially the case in the formation of acrylates such that it is possible to drive an ATRP reaction to higher conversion and prepare polymers with high molecular weight while retaining chain end functionality.

[0036] ARGET-ATRP processes begin with an initiation step where the metal catalyst, typically a copper catalyst, and a reducing agent are added to the reaction mixture. The reducing agent reduces the metal catalyst, converting it to its active form. Then the polymerization proceeds as usual with the active catalyst initiating and controlling chain growth. As the reaction progresses, the reducing agent continues to regenerate the active catalyst from any oxidized or deactivated species.IV. Ambient Cured Co-Reactive Additive Manufacturing.

[0037] Three dimensional objects formed from coreactive compositions are additively manufactured by extruding the coreactive composition, which may be in an at least partially reacted state, onto a surface, such as a build platform. The coreactive composition may be in an at least partially reacted state at the time of extrusion and thereafter fully react and cure to form a layer of the coreactive composition. Successive layers of either the same, or different coreactive compositions can be deposited, forming additional layers of material. The coreactive composition may be at least partially reacted when the coreactive components come together, such as in a mixing volume, just prior to extrusion. Alternatively, the two coreactive components could be premixed before extrusion and treated in a way to arrest thereaction (e.g., arrest curing of the coreactive composition), such as freezing the coreactive composition upon mixing.

[0038] It may be desirable to select the chemistry of each layer of the deposited coreactive composition such that covalent bonds between each successive layer of material are formed. Furthermore, different portions of the article can be printed from different coreactive compositions (e.g., a first coreactive composition printed to form a first portion of the object such as a base portion, an internal structure, etc., and a second coreactive composition printed to form a second portion of the object), and, depending on the chemical reactivity between the different coreactive compositions, covalent bonds might also form between different materials.

[0039] Specifically, an article may be printed so as to have a rigid portion and a flexible portion, a rigid portion and a foam-like portion, a tactile portion and a rigid and / or flexible portion, two portions comprising different densities, one or more conductive portions, one or more thermally / electrically conductive portions, two or more different colors, two or more different rheological profiles, two or more different materials comprising different affinities for water and / or solvent(s), and the like. The article may also be printed such that the coreactive compositions are deposited onto existing articles (e.g., other thermosets and / or thermoplastics, metals, woods, composite materials, ceramics, etc.) resulting in an article comprising both coreactive and non-coreactive compositions.

[0040] Additive manufacturing as described herein may result in an object having greater strength, particularly along the Z (e.g., vertical) axis, as compared to other extruded or printed parts due to the covalent bonding between the printed layers. Strong intralayer and interlayer covalent bonding results in not only stronger parts, but also in more uniform part geometries; that is, less print lines and / or portion differentials. The ability to form, in one process, objects having multiple substrates and / or portions comprising different coreactive or non-coreactive compositions is a further advantage.

[0041] Additive manufacturing using coreactive compositions, also referred to as ambient reactive extrusion, or ARE type three-dimensional printing, typically utilizes at least two components that react with each other (e.g., are coreactive). A first coreactive component (sometimes referred to herein as a first reactant group, a first reactive functional group, part A) and at least one second coreactive component (sometimes referred to herein as a second reactant group, second reactive functional group, part B), when extruded in combination and / or succession, chemically react with one another to form a coreactive composition.

[0042] A variety of chemistries may be employed in additive manufacturing of coreactive components. Each coreactive component may comprise at least one functional group that is reactive with the at least one functional group of the other coreactive component. For example, a first coreactive component may comprise a first functional group and a second coreactive component may comprise a second functional group, where the first functional group is reactive with the second functional group.

[0043] Alternatively, one or both of the first coreactive component and the second coreactive component may comprise two or more reactive functional groups such as from 2 to 20 functional groups, from 2 to 16, from 2 to 12, from 2 to 8, from 2 to 6, from 2 to 4, or from 2 to 3 reactive functional groups. When at least one of the first coreactive component and the second coreactive component has two or more reactive functional groups, the first and second coreactive components may react to form the coreactive composition via a dual cure reaction. The reactive functional groups may be terminal functional groups, pendant functional groups, or a combination of terminal and pendant functional groups.

[0044] During the dual cure, the two or more reactive functional groups of the first coreactive component and / or the second coreactive component may react or crosslink at the same time, such that coreactive composition can comprise may cure via two or more chemistries. For example, a first coreactive component may comprise an ethylenically unsaturated monomer, an isocyanate functional monomer, a ligand, and a catalyst (i.e., at least two different functional groups) and the second coreactive component may comprise an amine functional monomer and a reducing agent. The isocyanate functional monomer of the first coreactive component may react with the amine functional monomer of the second coreactive component and the ethylenically unsaturated monomer, ligand, and catalyst of the first coreactive component may react with the reducing agent of the second coreactive component at the same time. The dual cure chemical mechanism of this example includes ATRP and polyurea formation, as shown in Examples 10-14.

[0045] In another example, a first coreactive component may comprise an ethylenically unsaturated monomer, an isocyanate functional monomer, a ligand, and a catalyst (i.e., at least two different functional groups) and the second coreactive component may comprise an alcohol functional monomer and a reducing agent. The isocyanate functional monomer of the first coreactive component may react with the alcohol functional monomer of the second coreactive component and the ethylenically unsaturated monomer, ligand, and catalyst of the first coreactive component may react with the reducing agent of the second coreactivecomponent at the same time. The dual cure chemical mechanism of this example includes ATRP and polyurethane formation, as shown in Example 16.

[0046] The coreactive composition may thereafter cure under ambient conditions or, depending on the chemistry of the reaction, with the assistance of, for example, heat, actinic radiation, catalysts, addition of curing agents-post extrusion, etc. to form an object, or a portion of an object, comprising a thermosetting polymer (sometimes referred to as a thermoset), a thermoplastic polymer, or combinations thereof. At least the first coreactive component and the second coreactive component are chosen by one skilled in the art to result in the desired final product (e.g., thermoset, thermoplastic, etc.).

[0047] Table 1 describes suitable coreactive compositions and the coreactive components from which they can be formed. These coreactive compositions can be printed by any of the methods described herein, either alone or in combination, to form three dimensional objects.

[0048] The chemistries of ATRP and / or ARGET described above may be used in conjunction with, or as the components of, ARE co-reactive compositions to produce three- dimensional articles. As described above, ATRP methods involve a catalyst, typically based on a transition metal, a ligand, and a reducing agent. When used with the ARE co-reactive chemistries described herein, the catalyst and reducing agent are preferably separated into the first reactive component (e.g., part A) and the second reactive component (e.g., part B) respectively.Table 1Coreactive Compositions

[0049] Another advantage of additive manufacturing using coreactive compositions may be that the coreactive compositions can be three dimensionally printed at relatively low viscosity. Therefore, relatively large amounts (e.g., high relative weight percents) of additives and / or fillers can be included with the coreactive components while maintaining a printable viscosity. Both the type and / or the amount of additives can be selected or “tuned’- to result in desirable chemical and / or physical properties of the printed article. Coreactive compositions can be tuned with the addition of additives and / or fillers for desired mechanical performance (e.g., strength, elasticity, rigidity, sag resistance, etc.), surface features (e.g., hardness,texturing, smoothness, etc.), chemical resistance (e.g., solvent resistance, etc.), thermal resistance (including fire retardancy, etc.) or conductivity, and / or electrical insulation or conductivity. Coreactive compositions can also be tuned with the addition of one or more catalytic / activator / accelerant additives in any of the coreactive components to result in desirable reaction kinetics, such as rate of reaction.

[0050] Table 2 describes additives that can be included with any coreactive compositions, such as those described in Table 1. A selection of any of the additives can be included in, either, or both of, the first and second coreactive components (e.g., either, or both of the Part A / Part B), depending on the desired chemical and / or physical properties of the resulting object. In this case, Table 2 describes specific additives and fillers that may be suitable for ambient reactive extrusion-based three-dimensional printing, however, Table 2 is nonlimiting. Therefore, other additives may be included with the coreactive composition(s), such as additives known to those skilled in the coatings, extrusion, and thermoplastic areas.Table 2Additives / Fillers

[0051] Any suitable combination of coreactive composition(s) and optionally additive(s) / filler(s), can be printed by a three-dimensional printing system adapted for mixing and extruding feedstocks. Two or more volumetric metering pumps (e.g., positive displacement pumps, progressive cavity pumps, etc.) may each respectively discharge, in combination or succession, the two coreactive components associated with a coreactive composition (e.g., the first reactive component discharged by the first metering pump and the second coreactive component discharged by the second metering pump into a mixing volume). In some cases, the mixing volume can include mechanical (e.g., driven) mixing features. Upon entering the mixing volume, the first and second coreactive components begin to mix and react, and thereafter, are extruded through an extrusion print nozzle in an at least partially reacted state. Once extruded, the two coreactive components further react and cure, which, as described above, may be under ambient conditions, to form either a thermoset, a thermoplastic material, or combinations thereof.V. Additive Manufacturing Methods Utilizing a Radical Polymerization-Based Coreactive Composition

[0052] In the additive manufacturing methods of the present disclosure, two reactive components are co-extruded such that they react with each other via the ATRP mechanism, forming a radical polymerization-based coreactive composition, which is used to form a three dimensional article.

[0053] To utilize the benefits of the ATRP reaction, the first coreactive component may comprise a catalyst and a ligand, and the second reactive component may comprise a reducing agent. The first and second reactive components may also include any additional additives / fillers as described in Table 2 above.

[0054] The catalyst may be a transition-metal catalyst that includes copper, iron, nickel, ruthenium, osmium, or combinations of the foregoing. A particularly suitable catalyst is copper (II) bromide. The catalyst may be present in a total amount of at least 1 ppm, at least 5 ppm, at least 10 ppm, at least 15 pm, at least 20 ppm, at least 25 ppm, at least 30 ppm, at least 35 ppm, at least 40 ppm, or within any range encompassed by any two of the foregoingvalues as endpoints, based on the total concentration of the catalyst relative to a total concentration of the monomer. For example, the catalyst may be present in a total amount of from 1 ppm to 40 ppm, or from 15 ppm to 40 ppm.

[0055] The catalyst may be present in a total amount of as little as 0.001 wt. %, 0.01 wt. %, 0.1 wt. %, or as much as, or greater than, 0.15 wt.%, 0.5 wt.%, 1 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based upon the total weight of the first and second coreactive components. For example, the catalyst may be present in an amount of from 0.001 wt.%, to 1 wt.%, 0.0.01 wt.% to 0.5 wt.%, or 0.1 wt. % to 0.15 wt. %.

[0056] The first and / or second coreactive component may contain a ligand which, while not wishing to be bound by any mechanism / theory, helps control the polymerization process by coordinating to the metal catalyst and facilitating controlled growth of polymer chains. Suitable ligands include bipyridines, phosphines, N-heterocyclic carbenes, amines, phenanthrolines, and oxazolines. A particularly preferred ligand is bipyridine. The ligand may be present in the first and second coreactive component in total amount of as little as 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.06 wt.%, 0.07 wt.%, 0.08 wt.%, or as high as 0.09 wt.%, 0.10 wt.%, 0.11 wt.%, 0.12 wt.%, 0.13 wt.%, 0.14 wt.%, 0. 15 wt.%, 0.16 wt.%, 0.17 wt.%, 0.18 wt.%, 0.19 wt.%, 0.20 wt.%, 0.25 wt.%, 0.30 wt.%, 0.40 wt.%, 0.50 wt.%, 0.60 wt.%, 0.70 wt.%, 0.80 wt.%, 0.90 wt.%, 1 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based on the total weight of the first and second reactive components. For example, the ligand may be present in a total amount of from 0.01 wt.% to 1 wt.%, 0.01 wt.% to 0.5 wt.%, or 0.01 wt.% to 0.20 wt.%, based on the total weight of the first and second coreactive components.

[0057] While not wishing to be bound by any mechanism / theory, the reducing agent reduces the metal catalyst back to its active form. Suitable reducing agents include organotin compounds such as tin(II) ethylhexanoate or tin(II) octoate. In some embodiments, the reducing agent is present in a total amount of as little as 0.05 wt. %,0.1 wt. %, 0.12 wt. %, or as much as, or greater than, 0.15 wt.%, 0.2 wt.%, 0.25 wt.%, 0.227 wt.%, 0.3 wt.%, 0.35 wt.%, 0.37 wt.%, g 0.4 wt.%, 0.45 wt.%, 0.5 wt.%, 1 wt.%, 1.5 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based upon the total weight of the first and second coreactive components. For example, the reducing agent may be present in an amount of from 0.1 wt.%, to 1 wt.%, or 0.37 wt.% to 1.5 wt.%.

[0058] In addition to the catalyst, the reducing agent, and the ligand components, the radical polymerization-based coreactive composition may include any combination of an initiator (contained in either, or both of, the first and second coreactive components), at least one monomer (contained within either, or both, the first and second coreactive components), and rheology modifying filler(s) (contained within either, or both of, the first and second coreactive components.

[0059] While not wishing to be bound by any mechanism / theory, the initiator is used to initiate the polymerization and regenerate the active catalyst. Suitable initiators include alkyl halides such as ethyl 2-bromoisobutyrate, methyl 2-bromopropionate, and tosyl chloride, alpha-halogenated carboxylic acid esters, halogenated alkylbenzenes, and / or sulfonyl halides. In some embodiments, the initiator includes carbon-halogen bonds or sulfur-halogen bonds. The initiator may be present in a total amount of greater than 0.01 wt.%, greater than 0.05 wt.%, greater than 0.1 wt.%, greater than 0.2 wt.%, greater than 0.3 wt.%, greater than 0.4 wt.%, greater than 0.5 wt.%, greater than 0.6 wt.%, greater than 0.7 wt.%, greater than 0.8 wt.%, greater than 0.9 wt.%, greater than 1 wt.%, greater than 2 wt.%, greater than 3 wt.%, greater than 4 wt. %, greater than 5 wt. %, greater than 6 wt. %, greater than 7 wt. %, greater than 8 wt. %, greater than 9 wt. %, greater than 10 wt. %, or within any range encompassed by any two of the foregoing values as endpoints, based on the total weight of the first and second coreactive components. For example, the initiator may be present in an total amount of from 0. 1 wt.% to 1 wt.%, from 0. 1 wt.% to 3 wt. %, 0.2 wt.% to 4 wt.%, 0.3 wt.% to 5 wt.%, 0.4 wt.% to 6 wt.%, based on the total weight of the first and second coreactive components.

[0060] The molar ratio of the catalyst to the initiator may be as low as 0.00010:1, 0.00015: 1, 0.00020: 1, 0.00021:1, 0.00022:1, 0.0002: 1, 0.00024:1, 0.00025: 1, 0.00030:1, 0.00045:1, 0.00050:1, as high as 0.001:1, 0.01: 1, 0.02: 1, 0.025: 1; or within any range encompassed by any two of the foregoing values as endpoints. For example, the molar ratio of the catalyst to the initiator may be from 0.00010:1 to 0.025:1, 0.0002:1 to 0.0020: 1, 0.0002:1 to 0.002 or from 0.0002: 1 to 0.0003:1.

[0061] The coreactive composition may comprise at least one monomer, such as an ethically unsaturated monomer, an isocyanate functional monomer, an alcohol functional monomer, and an amine functional monomer.

[0062] Ethylenically unsaturated monomers may be any monomer that contain one or more double bonds between carbon atoms within its molecular structure. Examples ofsuitable ethylenically unsaturated monomers are: the esters of the acrylic and methacrylic acids, such as ethyl acrylate, butyl acrylate, 2-ethyl-hexyl acrylate, cyclohexyl-chloro- acrylate, isobutylchloro-acrylate, methyl-chloroacrylate, methyl-methacrylate, butylmethacrylate, stearyl-methacrylate, phenyl-methacrylate, isopropyl-methacrylate, cyclo- hexyl-methacrylate, 3,3-dimethyl-2-butyl-methacrylate, melamine acrylate, acrylonitrile, methacrylonitrile, the corresponding amides such as acrylamide and methacrylamide, optionally in the methylolated and / or subsequently esterified form with monovalent alcohols C1-C4.; vinyl esters and ethers such as vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, vinyl-ethyl-ether; aromatic compounds such as styrene, vinyl-toluene, 4- methyl-styrene, 4-methoxy-styrene, 3,4-dimethyl styrene, 2,6-dichloro-styrene, 2,4-dichloro- styrene, 2-chloro-styrene, 3-chloro-styrene, 4-chloro-styrene, 4- chloro-2-methyl-styrene; allyl compounds such as allyl alcohol and allyl acetate, and maleic anhydride. The ethylenically unsaturated monomer may be Miramer SC9610 or Miramer PU2100, both available from Mi Won Co., Ltd. The ethylenically unsaturated monomer may be present in either the first or second coreactive component in an amount as low as 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, or as high as 60 wt.%, 70 wt.%, 80 wt.%, 95 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based upon a total weight of the first and second reactive components. For example, the ethylenically unsaturated monomer may be present in either the first or second coreactive composition in a total amount of 10 wt.% to 95 wt.%, 20 wt.%, to 80 wt.%, or 30 wt.% to 70 wt.%, based upon a total weight of the first and second coreactive components.

[0063] Isocyanate functional monomers may be any monomer that comprises an isocyanate group (-NCO). Isocyanate functional monomers may be used in polymerization process to produce coreactive compositions such as polyurethanes and polyureas. Suitable isocyanate functional monomers may include toluene diisocyanate, methylene diphenyl diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4’-diisocyanate, and isophorone diisocyanate. A suitable isocyanate functional monomer may be Isonate 143 or other commercially available methylene diphenyl diisocyanate monomers.

[0064] The isocyanate functional monomer may be present in either the first or second coreactive component in an amount as low as 1 wt.%, 5 wt.%, 10 wt.%, or as high as 15 wt.%, 20 wt.%, 25 wt.%, , or within any range encompassed by any two of the foregoing values as endpoints, such as 1 wt.% to 25 wt.%, 5 wt.%, to 20 wt.%, or 10 wt.% to 15 wt.%, based upon a total weight of the first and second reactive components.

[0065] Amine functional monomers may be any monomer comprising an amino group (- NH2, -NHR, or -NR2). Amine functional monomers may be used to produce coreactive compositions such as polyamides, polyurethanes, and epoxies. Suitable amine functional monomers may include aniline, ethylene diamine, polyether amine hexamethylenediamine, methylamine, diaminodiphenylmethane, l,3-bis(aminomethyl)benzene, 4,4’- diaminodiphenylmethane, and 2,2-bis(4-aminophenyl)propane. A suitable amine functional monomer may be Versalink or other commercially available polyether amine monomers.

[0066] The amine functional monomer may be present in either the first or second coreactive component in an amount as low as 5 wt.%, 10 wt.%, 20 wt.%, or as high as 65 wt.%, 75 wt.%, 85 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, such as 5 wt.% to 85 wt.%, 10 wt.%, to 75 wt.%, or 15 wt.% to 65 wt.%, based upon a total weight of the first and second reactive components.

[0067] Alcohol functional monomers may be any monomer comprising an hydroxyl group (-OH). Alcohol functional monomers may be used to produce coreactive compositions such as polyurethanes, and polyesters. Suitable alcohol functional monomers may include polyols, such as ethanol, methanol, isopropanol, 1,4-butanediol, ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, 1,3-propanediol. A suitable alcohol functional monomers may be Capa-4101 or other commercially available polyester polyols.

[0068] The alcohol functional monomer may be present in either the first or second coreactive component in an amount as low as 1 wt.%, 5 wt.%, 10 wt.%, or as high as 15 wt.%, 20 wt.%, 30 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, such as 1 wt.% to 30 wt.%, 5 wt.%, to 20 wt.%, or 10 wt.% to 15 wt.%, based upon a total weight of the first and second reactive components.

[0069] While not wishing to be bound by any mechanism / theory, the molar ratio of unsaturated functional groups in the ethylenically unsaturated monomer to the initiator is included to control the polymerization kinetics and maintain the living polymerization. In some embodiments, the molar ratio of unsaturated functional groups of the ethylenically unsaturated monomer to the initiator may be as low as 5:1, 10:1, 15:1, 20:1, or as high as 25: 1, 30: 1, 35: 1, 40: 1 or within any range encompassed by any two of the foregoing values as endpoints. For example, the molar ratio of unsaturated functional groups in the ethylenically unsaturated monomer to the initiator may be from 5:1 to 40:1, from 15:1 to 40:1 or from 25:1 to 40:1.

[0070] While not wishing to be bound by any mechanism / theory, the rheology modifier is included to control the viscosity of the coreactive composition. Specifically, if the viscosity is too low, the composition will not hold its shape well during printing, which can result in poor build quality such as drooping, sagging, or even collapsing of the printed article. If the viscosity is too high, the composition may have difficulty flowing through the extrusion system, resulting in uneven or incomplete extrusion and leading to gaps and weak adhesion between layers. Additively manufacturing articles from acrylic -based coreactive compositions has proven to be difficult due to the low viscosity of the coreactive components and resulting coreactive composition. As shown by the Examples of the disclosure, using a rheology modifying filler, preferably in an amount of at least 3 wt.%, makes the acrylic -based composition printable.

[0071] The rheology modifying filler may be selected from any of the fillers discussed in Table 2. Particularly suitable rheology modifying fillers include fumed silica and nano clay. A suitable fumed silica is Cabosil TS-720, a fumed silica which has been surface treated with polydimethylsiloxane, available from Univar Solutions Inc. The rheology modifying filler of the radical polymerization-based coreactive composition may be present in a total amount of as low as 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, or as high as 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based upon a total weight of the first and second coreactive components. For example, the rheology modifying filler may be present in a total amount of from 1 wt.% to 10 wt.%, from 3 wt.% to 10 wt.%, or from 5 wt.% to 10 wt.%, based upon a total weight of the first and second coreactive components.

[0072] The viscosity of the first and / or second coreactive components, as determined by viscometer (e.g., Brookfield) at ambient temperature (e.g., 22.6 - 24.8 °C) and pressure (approximately 1.0 atm), may individually be as low as 100,000 cP, 150,000 cP, 175,000 cP, 200,000 cP, 250,000 cP, 275,000 cP, 300,000 cP, 325,000 cP, 350,000 cP, 368,000 cP, 375,000 cP, 400,000 cP, as high as 425,000 cP, 450,000 cP, 475,000 cP, 490,000 cP, 500,000 cP, 525,000 cP, 550,000 cP, 575,000 cP, 600,000 cP, 700,000 cP, 800,000 cP, 900,000 cP, 1 ,000,000 cP, or within any range encompassed by any two of the foregoing values as endpoints. For example, the viscosity of the first and / or second coreactive components may individually be from 100,000 cP to 1,000,000 cP, from 350,000 cP to 500,000 cP, or from 368,000 cP to 490,000 cP.

[0073] The first and second coreactive components may further comprise a small amount of solvent. It is preferable that the additive manufacturing compositions contain a minimal amount of solvent for reasons of safety and health, reduced post-processing, and environmental impact. In certain embodiments, one or both of the first and second coreactive components includes a solvent present in a total amount of as high as 10 wt.%, 9.5 wt.%, 9 wt.%, 8.5 wt.%, 8 wt.%, 7.5 wt.%, 7 wt.%, 6.5 wt.%, 6 wt.%, or as low as 5.5 wt.%, 5 wt.%, 4.5 wt.%, 4 wt.%, 3.5 wt.%, 3 wt.%, 2.5 wt.%, 2 wt.%, 1.5 wt.%, 1 wt.%, 0.10 wt. %, or within any range encompassed by any two of the foregoing values as endpoints, based upon a total weight of the first and second coreactive components. For example, one or both of the first and second reactive compositions may include a solvent present in a total amount of from 0.10 wt.% to 10 wt.%, from 1 wt.% to 7.5 wt.%, or from 1 wt.% to 5 wt.%, based upon a total weight of the first and second coreactive components.

[0074] The coreactive composition may further comprise a crosslinker, such as pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). The crosslinker may be present in the first and second coreactive component in total amount of as little as 1 wt.%, 5 wt.%, 10 wt.%, or as high as 30 wt.%, 40 wt.%, 50 wt.%, or within any range encompassed by any two of the foregoing values as endpoints, based on the total weight of the first and second reactive components. For example, the crosslinker may be present in a total amount of from 1 wt.% to 50 wt.%, 5 wt.% to 40 wt.%, or 10 wt.% to 30 wt.%, based on the total weight of the first and second coreactive components.VI. 3D Printing Methods

[0075] Any suitable combination of coreactive composition(s) and optionally additive(s) / filler(s) as described above, can be printed by a three-dimensional printing system adapted for mixing and extruding feedstocks. Two or more volumetric metering pumps (e.g., positive displacement pumps, progressive cavity pumps, etc.) may each respectively discharge, in combination or succession, the two coreactive components associated with a coreactive composition (e.g., the first reactive component discharged by the first metering pump and the second coreactive component discharged by the second metering pump into a mixing volume). In some cases, the mixing volume can include mechanical (e.g., driven) mixing features. Upon entering the mixing volume, the first and second coreactive components begin to mix and react, and thereafter, are extruded through an extrusion print nozzle in an at least partially reacted state. Once extruded, the two coreactive componentsfurther react and cure, which, as described above, may be under ambient conditions, to form either a thermoset, a thermoplastic material, or combinations thereof.

[0076] The co-extruding of the coreactive components may be carried out at relatively low temperatures such as high as 50°C, 45°C, 40°C, 35°C, 32°C, or as low as 30°C, 25°C, 20°C, 15°C, 10°C, or within any range encompassed by any two of the foregoing values as endpoints. For example, the co-extruding may be carried out at a temperature of from 10°C to 50°C, from 15°C to 45°C, or from 30°C to 40°C.

[0077] The co-extruding step may also be carried out in the absence of any actinic radiation such as alpha rays, gamma rays, X rays, UV light or any other wavelengths of light used in the curing or solidification of resins, such as those used in stereolithography and digital light processing technologies.

[0078] The co-extruding step may also be carried out in the absence of any photoinitiators including phosphine oxides, aryl ketones, benzophenones, hydroxylated ketones, and the like.

[0079] The co-extruding step may also be carried out in the absence of any peroxides or azo initiators such as 2,2-azobis(2-methylpropionitrile) (AIBN) and its derivatives.

[0080] The co-extruding step may also be carried out in the absence of an inert atmosphere such as nitrogen or argon. As the first and second co-reactive compositions are able to react via ATRP, the additive manufacturing methods of the present disclosure can be carried out in ambient air. In some embodiments, the ambient air may comprise an oxygen content of 10 vol. %, 15 vol. %, 20 vol. %, 21 vol. %, or within any range encompassed by any two of the foregoing values as endpoints. For example, the additive manufacturing methods of the present disclosure can be carried out in ambient air which comprises an oxygen content of 10 vol. % to 21 vol. %, or 15 vol. % to 20 vol. %.ASPECTS

[0081] Aspect 1 is a method of additive manufacturing, comprising: co-extruding a first coreactive component and a second coreactive component to form a coreactive composition, the first coreactive component comprising a catalyst and a ligand, and the second coreactive component comprising a reducing agent, the first and second coreactive components further comprising: an initiator contained within one or both of the first and second reactive components; an ethylenically unsaturated monomer contained within one or both of the first and second coreactive components; a rheology modifying filler contained within one or bothof the first and second coreactive components; and wherein the first and second coreactive components react via atom transfer radical polymerization (ATRP).

[0082] Aspect 2 is the method of Aspect 1, wherein a viscosity of the first and / or second coreactive component is 100,000 cP or greater, as determined by a viscometer at 23 °C.

[0083] Aspect 3 is the method of either Aspect 1 or Aspect 2, wherein the rheology modifying filler is present in a total amount of greater than 3 wt.%, based on a total weight of the first and second reactive components.

[0084] Aspect 4 is the method of any one of Aspects 1-3, wherein a molar ratio of the catalyst to the initiator is at least 0.00020:1.

[0085] Aspect 5 is the method of any one of Aspects 1-4, wherein the catalyst is present in a total amount of at least 15 ppm, based on a total concentration of the catalyst relative to a total concentration of the monomer.

[0086] Aspect 6 is the method of any one of Aspects 1-5, wherein the catalyst comprises a transition metal selected from copper, iron, nickel, ruthenium, osmium, and combinations of the foregoing.

[0087] Aspect 7 is the method of any one of Aspects 1-6, wherein one or both of the first and second reactive components further comprises a solvent present in a total amount of less than 7.5 wt.%, based on a total weight of the first and second reactive components.

[0088] Aspect 8 is the method of any one of Aspects 1-7, wherein the ethylenically unsaturated monomer is contained within both of the first and second reactive components.

[0089] Aspect 9 is the method of any one of Aspects 1-8, wherein the ethylenically unsaturated monomer is contained within only one of the first and second reactive components.

[0090] Aspect 10 is the method of any one of Aspects 1-9, wherein the ethylenically unsaturated monomer comprises at least one of an acrylic, styrene, an acrylamide, and maleic anhydride.

[0091] Aspect 11 is the method of any one of Aspects 1-10, wherein a molar ratio of unsaturated functional groups of the ethylenically unsaturated monomer to the initiator is at least 10: 1.

[0092] Aspect 12 is the method of any one of Aspects 1-11, wherein the initiator includes carbon-halogen bonds or sulfur halogen bonds and is present in a total amount of greater than 0.1 wt.%, based on a total weight of the first and second reactive components.

[0093] Aspect 13 is the method of any one of Aspects 1-12, wherein the reducing agent is present in a total amount of greater than 0.227 wt.%, based on a total weight of the first and second reactive components.

[0094] Aspect 14 is the method of any one of Aspects 1-13, wherein the co-extruding step is carried out in the absence of any of: exposure to temperatures greater than 32°C; actinic radiation / photoinitiators; peroxides; azo initiators; and an inert atmosphere.

[0095] Aspect 15 is the method of any one of Aspects 1-14, wherein the coextruding step is carried out in ambient air with an oxygen content of from 10 vol. % to 21 vol. %.

[0096] Aspect 16 is an article manufactured according to the method of any one of Aspects 1-15.

[0097] Aspect 17 is a coreactive composition comprising: a first coreactive component comprising a catalyst and a ligand; a second coreactive component comprising a reducing agent; wherein either the first coreactive component, the second coreactive component, or both the first coreactive component and the second coreactive component further comprise: an initiator, an ethylenically unsaturated monomer, and a rheology modifying filler; and the first coreactive component and second reactive component react via atom transfer radical polymerization (ATRP).

[0098] Aspect 18 is an article additively manufactured from the coreactive composition of Aspect 17.

[0099] Aspect 19 is a method of additive manufacturing, comprising: co-extruding a first coreactive component and a second coreactive component to form a coreactive composition, the first coreactive component comprising a catalyst and a ligand, and the second coreactive component comprising a reducing agent, the first and second coreactive components further comprising: an initiator contained within one or both of the first and second reactive components; an ethylenically unsaturated monomer contained within one or both of the first and second coreactive components; an isocyanate monomer contained within the first coreactive component; a monomer with alcohol or amine functionality contained within the second coreactive component; and a rheology modifying filler contained within one or both of the first and second coreactive components; wherein the first and second coreactive components react via a dual cure reaction.

[0100] Aspect 20 is the method of Aspect 19, wherein a viscosity of the coreactive composition is at least 100,000 cPs.

[0101] Aspect 21 is the method of either Aspect 19 or Aspect 20, wherein the rheology modifying filler is present in a total amount of greater than 3 wt.%, based on a total weight of the first and second reactive components.

[0102] Aspect 22 is the method of any one of Aspects 19-21, wherein a molar ratio of the catalyst to the initiator is at least 0.00024.

[0103] Aspect 23 is the method of any one of Aspects 19-22, wherein the catalyst is present in a total amount of at least 15 ppm, based on a total concentration of the catalyst relative to a total concentration of the monomer.

[0104] Aspect 24 is the method of any one of Aspects 19-23, wherein the catalyst comprises a transition metal selected from copper, iron, nickel, ruthenium, osmium and combinations of the foregoing.

[0105] Aspect 25 is the method of any one of Aspects 19-24, wherein one or both of the first and second reactive components further comprises a solvent present in a total amount of less than 7.5 wt.%, based on a total weight of the first and second reactive components.

[0106] Aspect 26 is the method of any one of Aspects 19-25, wherein the ethylenically unsaturated monomer is contained within both of the first and second reactive components.

[0107] Aspect 27 is the method of any one of Aspects 19-26, wherein the ethylenically unsaturated monomer is contained within only one of the first and second reactive components.

[0108] Aspect 28 is the method of any one of Aspects 19-27, wherein the ethylenically unsaturated monomer comprises at least one of an acrylic, styrene, an acrylamide, and maleic anhydride.

[0109] Aspect 29 is the method of any one of Aspects 19-28, wherein a molar ratio of unsaturated functional groups of the ethylenically unsaturated monomer to the initiator is at least 10:1.

[0110] Aspect 30 is the method of any one of Aspects 19-29, wherein the initiator includes carbon-halogen bonds or sulfur halogen bonds and is present in a total amount of greater than 0. 1 wt.%, based on a total weight of the first and second reactive components.

[0111] Aspect 31 is the method of any one of Aspects 19-30, wherein the reducing agent is present in a total amount of greater than 0.22 wt.%, based on a total weight of the first and second reactive components.

[0112] Aspect 32 is the method of any one of Aspects 19-31, wherein the ethylenically unsaturated monomer comprises at least one of an acrylic, styrene, an acrylamide, and maleic anhydride.

[0113] Aspect 33 is the method of any one of Aspects 19-32, wherein the isocyanate is contained within one of the first and second reactive components.

[0114] Aspect 34 is the method of any one of Aspects 19-33, wherein the amine or alcohol containing monomer is contained within one of the first and second reactive components.

[0115] Aspect 35 is the method of any one of Aspects 19-34, wherein the amine, alcohol, and isocyanate are present in a total amount between 23 - 73 wt% of the total composition.

[0116] Aspect 36 is the method of any one of Aspects 19-35, wherein the co-extruding step is carried out in the absence of any of: exposure to temperatures greater than 32°C; actinic radiation / photoinitiators; peroxides; azo initiators; and an inert atmosphere.

[0117] Aspect 37 is the method of any one of Aspects 19-36, wherein the composition is cured at an atmospheric oxygen level of at least 20%.

[0118] Aspect 38 is an article manufactured according to the method of any one of Aspects 19-37.

[0119] Aspect 39 is a coreactive composition, comprising: a first coreactive component comprising a catalyst, an isocyanate monomer, and a ligand; a second coreactive component comprising a reducing agent, and at least one of an amine and an alcohol containing monomer; wherein either the first coercive component, the second coreactive component, or both the first coreactive component and the second coreactive component further comprise: an initiator; an ethylenically unsaturated monomer; and a rheology modifying filler; and wherein the first coreactive component and second reactive component react via a dual cure chemistry.

[0120] Aspect 40 is a coreactive composition, comprising: a first coreactive component comprising a catalyst and a ligand; a second coreactive component comprising a reducing agent; wherein either the first coreactive component, the second coreactive component, or both the first coreactive component and the second coreactive component further comprise: an initiator, an ethylenically unsaturated monomer, and a rheology modifying filler; and the first coreactive component and second reactive component react via atom transfer radical polymerization (ATRP).

[0121] Aspect 41 is the coreactive composition of Aspect 40, wherein the first coreactive component further comprises an isocyanate monomer and the second coreactive component further comprises at least one of an amine and an alcohol containing monomer, or the first coreactive component further comprises at least one of the amine and the alcohol containing monomer, and the second coreactive component further comprises the isocyanate monomer.EXAMPLES

[0122] In the Examples below, all reagents were purchased from commercial sources and used as received without prior purification.Example 1; Coreactive composition formulation of an ARE print by ARGET ATRP separated by components in First and Second coreactive components with a tin reducing agent

[0123] In this example, a 3D printable, ARGET ATRP coreactive composition was printed. The two components of the coreactive composition were constructed using the compositions below.Table 3:Composition of the first and second coreactive components comprising the 3D printable ARGET ATRP coreactive composition.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per Melamine acrylate monomer

[0124] From Table 3, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in N-Methyl-2-pyrrolidone to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610). The mixture stirred at ambient temperature overnight. The homogeneous solution was green in color. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the first coreactive component.

[0125] From Table 3, Tin(II) 2-ethylhexanoate was added to the Melamine acrylate. The mixture stirred at ambient temperature for approximately ten minutes. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the second coreactrive component.

[0126] The first and second coreactive components were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The first and second coreactive components were then extruded, mixed, and printed at a volume mix ratio of 1 : 1.Example 2: Coreactive composition formulation of an ARE print by ARGET ATRP with 0.6 wt.% Tosyl chloride, 15 ppm catalyst, and 6.9 wt.% Ascorbyl Palmitate.

[0127] In this example, a 3D printable, ARGET ATRP coreactive composition was printed. The two core active components of the coreactive composition were constructed using the compositions below.Table 4:Composition of the first and second coreactive components comprising the 3D printable ARGET ATRP coreactive composition.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer.**Weight fraction and equivalents of reagents are given for the final composition of the extruded material, accounting for the volume mix ratio of 1: 10.

[0128] From Table 4, Copper(If) Bromide and bipyridine were weighed into a jar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610). The mixture stirred at room temperature overnight. The homogeneous solution was green in color. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the first coreactive component.

[0129] From Table 4, ascorbyl palmitate was added to the mixture stirred at room temperature for approximately ten minutes. This mixture and fumed silica (e.g., Cabosil TS- 720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the second coreactive component..

[0130] The A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The first and second coreactive components were then extruded, mixed, and printed at a volume mix ratio of 1:10.Example 3: Coreactive composition formulation of an ARE print by ARGET ATRP with 0.37 wt.% Tosyl Chloride, 0.8 wt.% Ascorbyl Palmitate, and 1156 ppm catalyst.

[0131] In this example, a 3D printable, ARGET ATRP formulation was printed. The two coreactive components of the coreactive composition were constructed using the compositions below.Table 5:Composition of the first and second coreactive components comprising the 3D printable ARGET ATRP coreactive composition.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer.

[0132] From Table 5, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610). The mixture stirred at room temperature overnight. The homogeneous solution was green in color. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the first coreactive component.

[0133] From Table 5, ascorbyl palmitate was added to the melamine acrylate. The mixture stirred at room temperature for approximately ten minutes. This mixture and fumedsilica were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the second coreactive component.

[0134] The A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The first and second coreactive components were then extruded, mixed, and printed at a volume mix ratio of 1: 1.Example 4: Coreactive composition formulation of an ARE print by ARGET ATRP with 5.9 wt.% Tosyl Chloride, 0.9 wt.% Ascorbyl Palmitate, and 1156 ppm catalyst.

[0100] In this example, a 3D printable, ARGET ATRP formulation was printed. The two coreactive components of the coreactive composition were constructed using the compositions below.Table 6:Composition of the first and second coreactive components comprising the 3D printable ARGET ATRP coreactive composition.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer.

[0101] From Table 6, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610). The mixture stirred at room temperature overnight. The homogeneous solution wasgreen in color. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the first coreactive component.

[0102] From Table 6, ascorbyl palmitate was added to melamine acrylate. The mixture stirred at room temperature for approximately ten minutes. This mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form the second coreactive component.

[0103] The A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The first and second coreactive components were then extruded, mixed, and printed at a volume mix ratio of 1:1.Example 5: Gel tests of coreactive compositions with 100% solids and no tin.

[0104] In this set of examples, the first and second coreactive components are mixed separately in vials, then blended, to assess the feasibility of printing coreactive compositions based upon cure rate. The gelation time is taken as the amount of time required to cure the resin into a thermoset in which a popsicle stick can no longer be removed from the cured resin after mixing by hand. All tests were done in open 2 dram vials at ambient conditions without prior purification of starting materials or exposure to external stimuli, such as heat or light.Table 7:Composition and Gel Times of ARGET ATRP coreactive composition without Tin or Solvent.3a[SC9610] refers to the molar equivalents of acrylic functional groups for the melamine acrylate monomer, assuming an average functionality of 5, relative to Tosyl Chloride. [TsCl] refers to the molar equivalents of Tosyl Chloride, which all reagents are scaled to. [Cu] refers to the molar equivalents of Copper (II) bromide relative to Tosyl Chloride, [bpy] refers to the molar equivalents of bipyridine relative to Tosyl Chloride. [RA] refers to the molar equivalents of Ascorbyl palmitate relative to Tosyl Chloride.bppm Cu is the parts per million concentration of copper relative to monomer, i.e. [Cu] / ([SC9610]+ [HPMA]) x 106.

[0105] From Tables 8-12, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610) inside of a 2 Dram clear glass vial. The mixture was stirred at room temperature until blended. The homogeneous solution was green in color. This formulation comprises the first coreactive component.

[0106] From Tables 8-12, ascorbyl palmitate was added to melamine acrylate inside a separate a 2 Dram clear glass vial. The mixture stirred at room temperature for approximately ten minutes. This mixture comprises the second coreactive component.

[0107] Component A was poured into the vial containing Component B by pipette. The blend was mixed vigorously using a popsicle stick for approximately 30 seconds then left to sit on the benchtop in the open vial. The gelation time is taken as the amount of time required to cure the resin into a thermoset in which the popsicle stick can no longer be removed from the cured resin.Table 8:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 23-MM-071A.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomerTable 9:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 23-MM-071B.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomerTable 10:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 23-MM-071C.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomerTable 11:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 23-MM-071D.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer.Table 12:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 23-MM-071 E.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomerExample 6: Gel tests with varied concentration of Tosyl Chloride with all reagents except Copper, ligand, and solvent in the first coreactive component.

[0108] The monomer and alkyl halide initiator (Tosyl chloride) could be placed in either component A or B, but copper (II) bromide and reducing agent must be stored in separate components prior to mixing. In this set of examples, the first coreactive component consists of all reagents except the copper (II) bromide / bipyridine catalyst dispersed in solvent. The cure reaction was started upon addition of the catalyst dispersion to the first coreactive component.

[0109] Similar to Example 5, gelation time is taken as the amount of time required to cure the resin into a thermoset in which a popsicle stick can no longer be removed from the cured resin after mixing by hand. All tests were done in open 2 dram vials at ambient conditions without prior purification of starting materials or exposure to external stimuli, such as heat or light.

[0110] The gel time (i.e., cure rate) could be tuned by loading of Tosyl Chloride, keeping the catalyst and reducing agent loading nearly constant.Table 13:Composition and Gel Times of ARGET ATRP coreactive composition with varied Tosyl Chloride Loading.3a[M600] refers to the molar equivalents of acrylic functional groups for the Miramer M600 monomer, assuming an average functionality of 6, relative to Tosyl Chloride. [TsCl] refers to the molar equivalents of Tosyl Chloride, which all reagents are scaled to. [Cu] refers to the molar equivalents of Copper (II) bromide relative to Tosyl Chloride, [bpy] refers to the molar equivalents of bipyridine relative to Tosyl Chloride. [Sn] refers to the molar equivalents of Tin (II) 2-ethylhexanoate relative to Tosyl Chloride.bppm Cu is the parts per concentration of copper relative to monomer, i.e. [Cu] / ([M600]+ [EHA]) x 106.

[0111] From Table 14-17, Copper(II) Bromide and bipyridine were weighed into a 2 Dram clear glass vial and dispersed in N-methyl to yield a catalyst stock solution. The catalyst stock solution comprises the first coreactive component.

[0112] From Table 14-17, Tosyl Chloride was diluted with 2-Ethylhexyl acrylate (EHA), then Miramer M600, then Tin(II) 2-ethylhexanoate to a separate 2 Dram clear glass vial. The mixture stirred at room temperature until it appeared visually homogeneous. This mixture comprises the second coreactive component.

[0113] The first coreactive component was poured into the vial containing the second coreactive component by pipette. The blend was mixed vigorously using a popsicle stick for approximately 30 seconds then left to sit on the benchtop in the open vial. The gelation time is taken as the amount of time required to cure the resin into a thermoset in which the popsicle stick can no longer be removed from the cured resin.Table 14:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 22-MM-026C.*Equivalents of total acrylic functional groups, assuming a functionality of 6 per MiramerM600 monomerTable 15:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 22-MM-026A.*Equivalents of total acrylic functional groups, assuming a functionality of 6 per MiramerM600 monomerTable 16:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 22-MM-026F*Equivalents of total acrylic functional groups, assuming a functionality of 6 per MiramerM600 monomerTable 17:Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 22-MM-026F.*Equivalents of total acrylic functional groups, assuming a functionality of 6 per Miramer M600 monomer.Example 7 : Gel tests of coreactive composition with Functional Monomers, with the reducing agent as the only reagent in the second coreactive component.

[0114] Acrylic monomers may contain other functional groups on the side chain of a monomer which can react through other cure chemistries. This can include alcohols, carboxylic acids, isocyanates, epoxy and anhydride functional groups. The compatibility of carboxyl, hydroxyl, isocyanate, ketone, and anhydride functional groups were assessed through gel test experiments similar to Examples 5 and 6.

[0115] In this set of examples, component A consists of all reagents except the tin reducing agent. The cure reaction was started upon addition of the tin reducing agent to the second coreactive component.

[0116] Similar to Examples 5 and 6, gelation time is taken as the amount of time required to cure the resin into a thermoset in which a popsicle stick can no longer be removed from the cured resin after mixing by hand. All tests were done in open 2 dram vials at ambient conditions without prior purification of starting materials or exposure to external stimuli, such as heat or light. In addition, the gel fraction was determined.

[0117] The gel fraction is a measurement of how much material was cured by removal of sol. The sol was removed by swelling the cured gel in solvent for a few days, which removes unreacted soluble fractions from the gel, then drying (e.g., under ambient conditions) the remaining gel. The gel fraction was calculated as the ratio of the final weight of the dried gel, divided by the initial weight of the gel prior to swelling.Table 18Composition and Gel Times of ARGET ATRP coreactive compositions with varied functional monomers / ‘'Reactions were conducted using a constant stoichiometry of [SC9610] / [M] / [TsCl] / [Cu] / [bpy] / [Sn] = 15 / 2 / 1 / 0025 / 0.05 / 0.5, where [SC910] refers to the molar equivalents of acrylic functional groups for the melamine acrylate monomer, assuming an average functionality of 5, relative to Tosyl Chloride. [TsCl] refers to the molar equivalents of Tosyl Chloride, which all reagents are scaled to. [Cu] refers to the molar equivalents of Copper (II) bromide relative to Tosyl Chloride, [bpy] refers to the molar equivalents of bipyridine relative to Tosyl Chloride. [Sn] refers to the molar equivalents of Tin (II) 2-ethylhexanoate relative to Tosyl Chloride. [M] refers to the additional monomer listed in Table 18. Figure 1 provides representative FT-IR spectra of gels taken after removal of sol show the presence of intact isocyanate and anhydride functional groups in the cured materials.Example 8: Gel tests of coreactive compositions with Multiple Multi-functional Acrylic Monomers, with tin as the only reagent in second coreactive component.

[0118] Multiple multi-functional monomers could be used to cure thermosets. This example uses Miramer SC9610, a melamine-acrylic with an average of five acrylic functional groups per molecule, with Miramer PU2100, an urethane functional acrylic with two acrylic functional groups per molecule. The tin catalyst is the only reagent in the second coreactive composition in this gel test experiment.

[0119] This formulation had a gel time of 19 minutes, with 1863 ppm of copper relative to all acrylic functional groups.Table 19Composition of the first and second coreactive components comprising the ARGET ATRP coreactive composition 22-MM-048D.*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer**Equivalents of total acrylic functional groups, assuming a functionality of 2 per Miramer PU2100 monomerExample 9; Comparative example - ARE print by ARGET ATRP coreactive compositions with 0.39 wt.% Tosyl Chloride, 0.98 wt.% Ascorbyl Palmitate, and 1156 ppm catalyst and varied filler loadings.

[0120] In this example, the ARGET ATRP formulation used in Example 3 were varied in filler content. The materials were characterized by Brookfield viscometry and characterized as printed objects. Printed objects with low loadings of filler, and low viscosity, tended to flow before additional layers could be printed.

[0121] From Table 20, Copper(II) Bromide and bipyridine were weighed into a jar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with melamine acrylate (e.g., Miramer SC9610). The mixture stirred at room temperature overnight. The homogeneous solution was green in color.

[0122] From Table 20, ascorbyl palmitate was added to melamine acrylate. The mixture stirred at room temperature for approximately ten minutes.Table 20Composition of the first and second coreactive components comprising an ARGET ATRP coreactive composition in absence of rheology modifying filler (e.g., cabosil).*Equivalents of total acrylic functional groups, assuming a functionality of 5 per melamine acrylate monomer.

[0123] Each respective mixture and fumed silica (e.g., Cabosil TS-720) were then weighed into a Max 300 L DAC cup from Flacktek in proportions described in Tables 21 and 22. The mixtures were dispersed via a typical Speedmixer procedure to form their respective Components. The viscosity of each component was measured by Brookfield viscometry inside of a 2.5 oz jar at ambient temperature (22.6 - 24.8°C). The measurements are reported in Tables 21 and 22 at a shear rate of 3 rpm using spindle number 4.Table 21First coreactive component with varied loadings of Cabosil filler.*Determined by Brookfield viscometry using a shear rate of 3 rpm and spindle number 7.Table 22Second coreactive Component with varied loadings of Cabosil filler.* Determined by Brookfield viscometry using a shear rate of 3 rpm and spindle number 7.

[0124] The first and second coreactive components were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The first and second coreactive components were then extruded, mixed, and printed at a volume mix ratio of 1:1. The printability of the formulations were measured by comparing the height of the dogbones against the height of the dogbone from the control formulation. This data is summarized in Table 23.Table 23Characterization of printed objects.Example 10: Printing of Formulation 1 - Thermoplastic Urea with 23 wt. % Acrylic

[0125] In this example, an acrylic / urea formulation was printed. The two components (Part A & B) of the formulation were constructed using the compositions below.Table 24: Composition of Part A and B Components Comprising the Coreactive Composition Formulation 1*Equivalents of total acrylic functional groups, assuming a functionality of 5 per Miramer SC9610 monomer

[0126] From Table 24, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with Miramer SC9610 and Isonate 143. The mixture was stirred at room temperature. The homogeneous solution was green in color. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part A.

[0127] From Table 24, Tin(II) 2-ethylhexanoate was added to Versalink. The mixture stirred at room temperature for approximately ten minutes. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part B.

[0128] Part A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The Part A and B components were then extruded, mixed, and printed at a weight mix ratio of 1 : 1.4.Example 11; Printing of Formulation 2 - Thermoplastic Urea

[0129] In this example, a 3D printable, urea formulation 2 was printed. The two components (Part A & B) of the formulation were constructed using the compositions below. Table 25: Compositions of the Part A and B Components Comprising the Coreactive Composition

[0130] From Table 25, Isonate 143 and Cabosil TS-720 were weighed into a Max 300 E DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part A.

[0131] From Table 25, Versalink and Cabosil TS-720 were weighed into a Max 300 E DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part B.

[0132] The Part A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The Part A and B components were then extruded, mixed, and printed at a weight mix ratio of 1:3.6.Example 12: Printing of Formulation 3 - Thermoplastic Urea with 47 wt. % Acrylic

[0133] In this example, a 3D printable, ARGET ATRP coreactive composition was printed. The two parts (A & B) of the formulation were constructed using the compositions below.Table 26: Composition of Part A and B Components Comprising the ARGET ATRP Coreactive Composition Formulation 3*Equivalents of total acrylic functional groups, assuming a functionality of 5 per Miramer SC9610 monomer.

[0134] From Table 26, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with Miramer SC9610 and Isonate 143. The mixture was stirred at room temperature. The homogeneous solution was green in color. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Component I-A.

[0135] From Table 26, Tin(II) 2-ethylhexanoate was added to Versalink. The mixture stirred at room temperature for approximately ten minutes. This mixture and Cabosil TS- 720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part B.

[0136] The Part A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. The A and B components were then extruded, mixed, and printed at a weight mix ratio of 1.4:1.Example 13: Printing of Formulation 4 - Thermoplastic Urea with 73 wt. % Acrylic

[0137] In this example, a 3D printable, ARGET ATRP coreactive composition formulation was printed. The two components (Part A & B) of the formulation were constructed using the compositions below.Table 27: Composition of Part A and B Components Comprising the ARGET ATRP Coreactive Composition Formulation♦Equivalents of total acrylic functional groups, assuming a functionality of 5 per Miramer SC9610 monomer.

[0138] From Table 27, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with Miramer SC9610 and Isonate 143. The mixture was stirred at room temperature. The homogeneous solution was green in color. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part A.

[0139] From Table 27, Tin(II) 2-ethylhexanoate was added to Versalink. The mixture stirred at room temperature for approximately ten minutes. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part B.

[0140] Part A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. Part A and B components were then extruded, mixed, and printed at a weight mix ratio of 4.7: 1.Example 14: Printing of Formulation 5 - Thermoset Urea with 50.6 wt. % Acrylic

[0141] In this example, a 3D printable, ARGET ATRP formulation was printed. The two components (Part A & B) of the formulation were constructed using the compositions below.Table 28: Composition of Part A and B Components Comprising ARGET ATRP Coreactive Composition Formulation 5*Equivalents of total acrylic functional groups, assuming a functionality of 5 per Miramer SC9610 monomer.

[0142] From Table 28, Copper(II) Bromide and bipyridine were weighed into ajar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with Miramer SC9610 and Isonate 143. The mixture was stirred at room temperature. The homogeneous solution was green in color. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part A.

[0143] From Table 28, Tin(II) 2-ethylhexanoate was added to Versalink. The mixture stirred at room temperature for approximately ten minutes. This mixture and Cabosil TS-720 were then weighed into a Max 300 L DAC cup from Flacktek. The formulation was then dispersed via a typical Speedmixer procedure to form Part B.

[0144] Part A and B formulations were transferred from the DAC cup to an Optimum cartridge via Flacktek SpeedDisc to be suitable for 3D printing by ambient reactive extrusion via Viscotec 2k extruders mounted to a gantry such as the Lulzbot Taz 6. Part A and B components were then extruded, mixed, and printed at a weight mix ratio of 1.6: 1.Example 15: Tensile Testing of Printed Dog Bones

[0145] The tensile properties of Formulations 1-5 (Examples 11-15) were determined on an Intron Model 5567 at a 50 mm / min pull rate using type IV specimens according to ASTM D638. Tensile specimens were 3D printed using custom G-codes. Properties are summarized in Table 29.Table 29: Tensile properties of printed acrylic / urea materialsExample 16: Gel Test of Acrylic / Urethane Chemistry with 51.8 wt.% Acrylic and No Tin Catalyst

[0146] In this set of examples, Parts A and B, according to the formulation in Table 30, are mixed separately in vials, then blended, to assess the feasibility of the printing formulation based upon cure rate. The gelation time is taken as the amount of time required to cure the resin into a thermoset in which a popsicle stick can no longer be removed from the cured resin after mixing by hand. The mixing was done in open 2 dram vials at ambient conditions without prior purification of starting materials or exposure to external stimuli, such as heat or light.Table 30: Composition of Part A and B Components Comprising an Acrylic / Urethane Gel*Equivalents of total acrylic functional groups, assuming a functionality of 5 per Miramer SC9610 monomer

[0147] From Table 30, Copper(II) Bromide and bipyridine were weighed into jar and dispersed in hydroxypropyl methacrylate to yield a catalyst stock solution. The catalyst stock solution was added to solid Tosyl Chloride and diluted with Miramer SC9610 then IPDI- D4000 inside of a 2 Dram clear glass vial. The mixture was stirred at room temperature until blended. The homogeneous solution was green in color. This formulation comprises Part A.

[0148] From Table 30, ascorbyl palmitate was suspended in Cappa-4101 inside a separate a 2 Dram clear glass vial. The mixture was vigorously blended using a popsicle stick. This mixture comprises Part B.

[0149] Part A was poured into the vial containing Part B by pipette. The blend was mixed vigorously using a popsicle stick for approximately 30 seconds then left to sit on the benchtop in the open vial. The gelation time was determined to be 4 minutes and 36 seconds, taken as the amount of time required to cure the resin into a thermoset in which the popsicle stick can no longer be removed from the cured resin.

Claims

CLAIMSWhat is claimed is:

1. A method of additive manufacturing, comprising: co-extruding a first coreactive component and a second coreactive component to form a coreactive composition, the first coreactive component comprising a catalyst and a ligand, and the second coreactive component comprising a reducing agent, the first and second coreactive components further comprising: an initiator contained within one or both of the first and second reactive components; an ethylenically unsaturated monomer contained within one or both of the first and second coreactive components; a rheology modifying filler contained within one or both of the first and second coreactive components; and wherein the first and second coreactive components react via atom transfer radical polymerization (ATRP).

2. The method of claim 1, wherein: the first coreactive component further comprises an isocyanate monomer and the second coreactive component further comprises at least one of an amine and an alcohol containing monomer, or the first coreactive component further comprises at least one of the amine and the alcohol containing monomer, and the second coreactive component further comprises the isocyanate monomer.

3. The method of claim 2, wherein the isocyanate containing monomer and the at least one of the amine and the alcohol containing monomer are present in a total amount of 23-73 wt. %, based on a total weight of the first and second coreactive components.

4. The method of any one of claims 1-3, wherein a viscosity of the first and / or second coreactive component is 100,000 cP or greater, as determined by a viscometer at 23 °C.

5. The method of any one of claims 1-4, wherein the rheology modifying filler is present in a total amount of greater than 3 wt.%, based on a total weight of the first and second reactive components.

6. The method of any one of claims 1-5, wherein at least one of a molar ratio of the catalyst to the initiator is at least 0.00020: 1 ; the catalyst is present in a total amount of at least 15 ppm, based on a total concentration of the catalyst relative to a total concentration of the monomer; and wherein the catalyst comprises a transition metal selected from copper, iron, nickel, ruthenium, osmium, and combinations of the foregoing.

7. The method of any one of claims 1-6, wherein the ethylenically unsaturated monomer is contained within both of the first and second reactive components.

8. The method of any one of claims 1-7, wherein the ethylenically unsaturated monomer is contained within only one of the first and second reactive components.

9. The method of any one of claims 1-8, wherein the ethylenically unsaturated monomer comprises at least one of an acrylic, styrene, an acrylamide, and maleic anhydride.

10. The method of any one of claims 1-9, wherein a molar ratio of unsaturated functional groups of the ethylenically unsaturated monomer to the initiator is at least 10:1.

11. The method of any one of claims 1-10, wherein the initiator includes carbon-halogen bonds or sulfur halogen bonds and is present in a total amount of greater than 0.1 wt.%, based on a total weight of the first and second reactive components.

12. The method of any one of claims 1-11, wherein the reducing agent is present in a total amount of greater than 0.227 wt.%, based on a total weight of the first and second reactive components.

13. The method of any one of claims 1-12, wherein the co-extruding step is carried out in ambient air with an oxygen content of from 10 vol. % to 21 vol. % and in the absence of any of: exposure to temperatures greater than 32°C; actinic radiation / photoinitiators ; peroxides; azo initiators; and an inert atmosphere.

14. A coreactive composition comprising: a first coreactive component comprising a catalyst and a ligand; a second coreactive component comprising a reducing agent; wherein either the first coreactive component, the second coreactive component, or both the first coreactive component and the second coreactive component further comprise: an initiator, an ethylenically unsaturated monomer, and a rheology modifying filler; and the first coreactive component and second reactive component react via atom transfer radical polymerization (ATRP).

15. The coreactive composition of claim 14, the first coreactive component further comprises an isocyanate monomer and the second coreactive component further comprises at least one of an amine and an alcohol containing monomer, or the first coreactive component further comprises at least one of the amine and the alcohol containing monomer, and the second coreactive component further comprises the isocyanate monomer.

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