Synthesis of precision polyacrylonitrile for ultra-high-performance carbon fibers and uses therein

Abstract

The present disclosure generally relates to copolymers of polyacrylamide, carbon fibers and carbon fiber composites comprising the copolymers of polyacrylamide, and the synthesis of the copolymers comprising precision polyacrylonitrile for ultra-high-performance carbon fibers and their uses therein.

Description

SYNTHESIS OF PRECISION POLYACRYLONITRILE FOR ULTRA-HIGH- PERFORMANCE CARBON FIBERS AND USES THEREINCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application Serial Nos. 63 / 669,226 filed on July 9, 2024 and 63 / 669,607 filed on July 10, 2024, the disclosures of each are incorporated herein by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.MATERIAL INCORPORATED-BY-REFERENCE

[0003] Not applicable.FIELD OF THE INVENTION

[0004] The present disclosure generally relates to copolymers of polyacrylamide, carbon fibers and carbon fiber composites comprising the copolymers of polyacrylamide, and the synthesis of the copolymers comprising precision polyacrylonitrile for ultra- high-performance carbon fibers and their uses therein.BACKGROUND OF THE INVENTION

[0005] Carbon fiber (CF)-based composites are five times stronger than steel and only a fraction of the weight. They serve as critical manufacturing materials in the aerospace, automobile, civil engineering, and energy storage industries. The market for CFs and related composites is predicted to reach $16-20 billion dollars by 2030. Even with this tremendous growth, over 90% of CFs are currently made from a precursor polymer called polyacrylonitrile (PAN), which is expensive and typically prepared using uncontrolled free radical polymerization methods that yield PAN of moderate molecular weight (A / „ = 70-200 kDa), broad poly dispersity (£) = 2-3), and with no control over the stereochemistry of the polymer backbone (i.e., -30% meso triads). This lack of complete structural control means that cunent CFs and composites only tap into a fraction of their potential in terms of overall strength and stiffness.

[0006] Over 90% of CFs are currently made from a precursor polymer called polyacrylonitrile (PAN), which is typically expensive and prepared using uncontrolledfree radical polymerization methods that yield PAN of moderate molecular weight ( = 70- 200 kDa), broad poly dispersity (£> = 2- 3), and with no control over the stereochemistry of the polymer backbone (i.e., -30% meso triads). This lack of complete structural control means that cunent CFs and composites only tap into a fraction of their potential in terms of overall strength and stiffness.

[0007] CF composite materials are manufactured from the precursor polymer PAN through a series of high-temperature curing steps (FIG. 1 A) that yield -1 lb of CF per -2 lbs of PAN. The 50% loss is because the carbonization and graphitization steps take place in furnaces heated to 200-300 °C and 1200-1500 °C, respectively. These curing steps induce cyclization of the side-chain nitrile groups of PAN (FIG. IB), followed by the burning off of any non-carbon atoms and generating a chemical structure resembling that of graphene. However, commercial PAN is often medium molecular weight (70-200 kDa) and does not possess well-defined positioning of the nitrile groups (i.e., atactic). Thus, a smaller percentage of graphene-like structures are formed under thermal treatment, which limits the mechanical properties and potential performance of the resultant CFs.SUMMARY OF THE INVENTION

[0008] Among the various aspects of the present disclosure is the provision of synthesis methods for precision polyacrylonitrile used to produce ultra-high-performance carbon fibers.

[0009] In one aspect, copolymers described herein comprise repeat units having the structure of Formula 1 and Formula 2:In Formula 1 and Formula 2, Ri may be hydrogen or an alkyl group. In some cases, Ri may be hydrogen or a Ci to G, alkyl group. In other cases, Ri may be hydrogen or a Ci to C3 alkyd group. In certain instances, Ri may be hy drogen. Additionally, R2 in Formula 1 and Formula 2 may be an alkyl group. In some cases, R2 may be a Ci to alkyl group. In other cases, R2 may be a branched C3 to Ce alkyl group. Examples of R2 groups mayinclude iso-propyl, iso-butyl, iso-pentyl, sec-butyl, sec-pentyl, tert-butyl, or tert-pentyl. In certain instances, R2 may be iso-propyl or tert-butyl. In some cases, R2 may be tertbutyl.

[0010] Additionally, the copolymers may comprise a block of repeat units having the structure of Formula 1 and another block of repeat units having the structure of Formula 1A, and optionally a block of repeat units having the structure of Formula 2:(2) wherein Ri is hydrogen or alkyl; R2 is alkyl; and n+n1is an integer of from about 500 to about 80000; and wherein the block of repeat units of Formula 1 comprise nitrile pendant groups that are atactic and the block of repeat units of Formula 1 A comprise nitrile pendant groups that are isotactic (meso-meso triad) and has a weight average molecular weight (Mw) of from about 20 kilodaltons (kDa) to about 5000 kDa.

[0011] The copolymers described herein may be prepared by a method comprising forming a reaction mixture, exposing the reaction mixture to visible or ultraviolet (UV) light, and dehydrating the resulting poly (alkyl acrylamide).

[0012] Other objects and features will be in part apparent and in part pointed out hereinafter.DESCRIPTION OF THE DRAWINGS

[0013] Those of skill in the art will understand that the drawings, described below, are for illustrative purposes only. The drawings are not intended to limit the scope of the present teachings in any way.

[0014] FIG. 1 A is a scheme for a two-step synthesis involving postpolymerization modification was used to prepare PAN-TB copolymer. The byproducts, isobutylene, SO2, and HC1, of the second step help the dehydration reaction proceed.

[0015] FIG. IB is an IR spectra of Sigma PAN, precursor PTBAM, and PAN-TB polymers. The diagnostic nitrile stretch is shown in the dashed box. The spectra areoffset from the recorded %Transmittance (0% for Sigma PAN, 5% for aPTBAM, and an additional 15% for each subsequent trace) for improved comparison.

[0016] FIG. 1C includes GPC traces of Sigma PAN, precursor PTBAM, and PAN-TB polymers baseline corrected to remove residual solvent peaks (DMF mobile phase, 60 °C, 0.025M LiBr).

[0017] FIG. 2 is aJH NMR (500 MHz, 25 °C, (CD3)2SO) spectrum for iPNIPAM.

[0018] FIG. 3 is aXH NMR (500 MHz, 25 °C, (CD3)2SO) spectrum for aPNIPAM.

[0019] FIG. 4 is an analytical GPC (DMF column, 0.025 M LiBr, 60 °C) of PTBAM and PNIPAM polymers..

[0020] FIG. 5A is a 'H NMR of Sigma PAN, aPAN-TB, and 1PAN-TB. Spectra was obtained in DMSO-de at 25 °C on a 500 MHz NMR instrument.

[0021] FIG. 5B is a1H NMR of 1PAN-TB with peaks used for conversion calculations highlighted. Spectra was obtained in DMSO-de at 25 °C on a 500 MHz NMR instrument.

[0022] FIG. 5C and 5D) are13C NMR of Sigma PAN, aPAN-TB, and 1PAN-TB with tacticity labeled. All spectra were obtained in DMSO-de at 25 °C on a 500 MHz NMR instrument.

[0023] FIG. 6 is a representative example of how percent conversion of the post polymerization modification reactions were calculated.

[0024] FIG. 7A is a simplified view of the stabilization mechanism upon heating the as-spun PAN copolymers in a muffle furnace at 250 °C (only acrylonitrile subunits shown for clarity).

[0025] FIGs. 7B, 7C, 7D, 7E, 7F, and 7G are SEM images of the Sigma PAN, aPAN-TB, and iPAN-TB fibers as-spun (B-D, respectively) and after processing in a muffle furnace at 250 °C (E-G, respectively). All images were collected with an ETD at 200-250x magnification utilizing a potential of 1.00 kV and a spot size of 3-4 to avoid excessive charging of organic fibers.

[0026] FIG. 8A is mechanical testing data for iPAN-TB as-spun (as) and muffle furnace-processed (m) fibers.

[0027] FIG. 8B is mechanical testing data for aPAN-TB (as) and (m).

[0028] FIG. 8C is mechanical testing data for Sigma PAN (as) and (m).

[0029] FIG. 8D is a plot of tensile modulus versus tensile strength illustrates thechange in mechanical properties post-furnace treatment. The trace marked with an asterisk is a random artifact during the measurement that did not affect the data.DETAILED DESCRIPTION OF THE INVENTION

[0030] Currently, over 90% of carbon fibers (CFs) are made from polyacrylonitrile (PAN), which is typically prepared as a copolymer through an uncontrolled free radical polymerization that often yields a broad poly dispersity (£) > 2) and little to no control over the stereochemistry in the polymer backbone (i.e., -30% meso-meso (mm) triads). PAN-based CFs are fabricated through a series of high- temperature curing steps on wet-spun fiber precursors that leads to cyclization of the nitrile groups and oxidation, followed by the formation of graphitic crystallites during the final carbonization step. The extent of graphitization is expected to be highly dependent on the stereochemistry of the original precursor polymer. Here, we introduce a new approach to synthesizing isotactic PAN (iPAN) using a two-step chemical process that starts with a Lewis acid-based stereocontrolled polymerization of N-tert- butylacrylamide (TBAM) monomer to make low dispersity (£> < 1.25) isotactic poly( / e / 7-butylacrylamide) (iPTBAM; Mw-150 kDa; -77% mm triads), followed by a post-polymerization pseudo-dehydration step to convert the majority of acrylamide functional groups to nitriles (-78%). The same post-polymerization method was applied to an atactic PTBAM that was prepared without using a Lewis acid. Success of the postpolymerization method that yielded iPAN-TB and aPAN-TB was confirmed using IR and 'H NMR spectroscopy. Each copolymer, along with a control PAN (Mv- 130 kDa) sourced from Sigma-Aldrich, was wet spun into precursor fibers, followed by thermally processing them in muffle (250 °C) and tube (1500 °C) furnaces. The results from tensile experiments (pre- and post-muffle furnace) showed aPAN-TB had the highest overall tensile modulus and strength, yet iPAN-TB ’s tensile modulus and strength increased six- and five-fold, respectively, upon heating while also counterintuitively becoming more elastic.

[0031] Carbon fiber (CF)-based composites are five-times stronger than steel and only a fraction of the w eight. They serve as critical manufacturing materials in the aerospace, automobile, civil engineering, and energy storage industries.1Although cotton and Rayon were originally pursued to make CFs after thermal processing, Akio Shindo in Japan demonstrated in the early 1960’s the first heat-treated polyacrylonitrile (PAN)- based CFs, which exhibited tensile modulus values as high as 140 GPa. In 1970, Toraylicensed Shindo’s patents and worked to scale up the production of PAN-based CFs to one ton per month.1Currently, greater than 90% of CFs are made from the precursor polymer PAN,2which is typically prepared through an uncontrolled free radical polymerization consisting of 90-95% acrylonitrile that is mixed with methacrylate and itaconic acid,3the latter of which helps with the carbonization step.4This polymerization yields an atactic polyacrylonitrile (aPAN) copolymer consisting of moderate molecular weight (Mw= 70-150 kDa), broad poly dispersity (£> > 2), and little to no control over the stereochemistry in the polymer backbone (i.e., -30% meso-meso (mm) triads).5

[0032] It has been reported in the literature6’7that the bottom-up process by which the PAN nitrile sidechain groups are cyclized (i.e., stabilized) largely depends on the extent of isotacticity in the polymer backbone.8In other words, cyclization can occur over larger segments or distances along the polymer backbone if several nitrile groups are all oriented similarly, leading to larger graphene nanoribbon-like structures that can continue to cyclize and react during subsequent carbonization steps at higher temperatures, ultimately yielding larger graphitic crystallites.9’10

[0033] Attempts to synthesize iPAN have been made previously, however, they either failed to control the stereochemistry of the resultant PAN product and only produced aPAN,11or they made iPAN that was low in molecular weight (only 17-20 kDa) and therefore not ideal for long-range polymer alignment that is ideal for making carbon fibers.12For example, in 2016 Matyjaszewski and co-workers reported11the aqueous-based polymerization using atom transfer radical polymerization (ATRP) in the presence of NaSCN or ZnCh, where Lewis acids have been reported13’14previously to help direct the stereochemistry during the monomer addition and chain extension steps. However, after producing a series of low molecular weight PAN products (on the order of -13 kDa), they used13C NMR to quantify the extent of isotactic mm triads and found that their approach did not improve the degree of isotacticity in PAN versus commercially available PAN that was purchased from Sigma- Aldrich. In a separate study in 2020, Oyaizu and co-workers reported the synthesis of iPAN using a templated approach, where the radical polymerization of acrylonitrile (AN) was performed inside a crystalline lattice of C0CI2 that yielded iPAN with 93% mm triads. Although this is the best isotacticity for iPAN reported to date, this templated approach afforded low molecular weights (17-20 kDa), high dispersities (£> = 3.0), and small quantities of the PAN product. Additionally, the authors, nor any other researchers to the best of our knowledge, have ever used iPAN prepared from this method to make CFs. This lack ofadoption is likely due to the lower molecular weights and quantities that were obtained in the 2020 study. Although there have been many attempts to synthesize iPAN, there exist no examples to date where PAN is simultaneously low dispersity, high molecular weight (MW > 150 kDa), and possesses a high degree of isotacticity in the polymer backbone.Copolymers

[0034] The present disclosure relates to copolymers comprising repeat units of two or more of Formula 1, Formula 1A, and Formula 2. In some cases, the copolymers may include blocks or segments with different tacticity, such as atactic and isotactic regions. The copolymers described herein may have high molecular weights and a controlled degree of isotacticity in certain segments.

[0035] In some cases, the copolymers may be used to produce carbon fibers. The carbon fibers derived from these copolymers may exhibit improved mechanical properties compared to conventional polyacrylonitrile-based carbon fibers.

[0036] The carbon fibers produced from the disclosed copolymers may be incorporated into composite materials. In some cases, carbon fiber composites comprising fibers derived from the copolymers may demonstrate enhanced strength, stiffness, and other desirable characteristics. These composites may find applications in aerospace, automotive, sporting goods, and other industries where high-performance materials are required.

[0037] The copolymers, carbon fibers, and composites described herein may provide advantages in terms of processability, mechanical properties, and versatility compared to existing materials. The ability to control the tacticity and composition of different segments within the copolymer structure may allow for tuning of properties to meet specific application requirements.

[0038] The copolymers described herein comprise repeat units having the structure of Formula 1 and Formula 2:

[0039] In Formula 1 and Formula 2, Ri may be hydrogen or an alkyl group. Insome cases, Ri may be hydrogen or a Ci to Cg alkyl group. In other cases, Ri may be hydrogen or a Ci to C3 alkyl group. In certain instances, Ri may be hydrogen.

[0040] Additionally, R2 in Formula 1 and Formula 2 may be an alkyl group. In some cases, R2 may be a Ci to Cg alkyl group. In other cases, R2 may be a branched C3 to Cg alkyl group. Examples of R2 groups may include iso-propyl, iso-butyl, iso-pentyl, secbutyl, sec-pentyl, tert-butyl, or tert-pentyl. In certain instances, R2 may be iso-propyl or tert-butyl. In some cases, R2 may be tert-butyl.

[0041] The sum of m and n in the copolymer structure may be an integer from about 500 to about 80,000. This range corresponds to the total number of repeat units in the copolymer.

[0042] In some instances, the copolymer may comprise a block of repeat units having the structure of Formula 1 and another block of repeat units having the structure of Formula 1A, and optionally a block of repeat units having the structure of Formula 2:wherein Ri is hydrogen or alkyl; R2 is alkyl; and n+n1is an integer of from about 500 to about 80000; wherein the one or more blocks of repeat units of Formula 1 comprise nitrile pendant groups that are atactic and the one or more blocks of repeat units of Formula 1A comprise nitrile pendant groups that are isotactic (meso-meso triad); and the one or more optional blocks of repeat units of Formula 2 are either atactic or isotactic (meso-meso triad) and has a weight average molecular weight (Mw) of from about 20 kilodaltons (kDa) to about 5000 kDa.

[0043] In further instances, the copolymer may comprise a block of repeat units having the structure of Formula 1 and another block of repeat units having the structure of Formula 1A:

[0044] The block of repeat units having the structure of Formula 1 may comprise nitrile pendant groups that are atactic. In contrast, the block of repeat units having the structure of Formula 1A may comprise nitrile pendant groups that are isotactic (mesomeso triad).

[0045] The copolymers described herein may have a controlled degree of isotacticity in certain segments, which may influence the properties of the resulting materials. The combination of atactic and isotactic blocks within the copolymer structure may allow for tuning of various characteristics, such as mechanical properties and processability.

[0046] The copolymers described herein may have a weight average molecular weight (Mw) ranging from about 20 kilodaltons (kDa) to about 6000 kDa, from about 20 kilodaltons (kDa) to about 5000 kDa, from about 20 kilodaltons (kDa) to about 4000 kDa, from about 20 kilodaltons (kDa) to about 3000 kDa, from about 20 kilodaltons (kDa) to about 2000 kDa, from about 50 kilodaltons (kDa) to about 6000 kDa, from about 50 kilodaltons (kDa) to about 5000 kDa, from about 50 kilodaltons (kDa) to about 4000 kDa, from about 50 kilodaltons (kDa) to about 3000 kDa, from about 50 kilodaltons (kDa) to about 2000 kDa, from about 100 kilodaltons (kDa) to about 6000 kDa, from about 100 kilodaltons (kDa) to about 5000 kDa, from about 100 kilodaltons (kDa) to about 4000 kDa, from about 100 kilodaltons (kDa) to about 3000 kDa, from about 100 kilodaltons (kDa) to about 2000 kDa, from about 200 kilodaltons (kDa) to about 6000 kDa, from about 200 kilodaltons (kDa) to about 5000 kDa, from about 200 kilodaltons (kDa) to about 4000 kDa, from about 200 kilodaltons (kDa) to about 3000 kDa, or from about 200 kilodaltons (kDa) to about 2000 kDa. In some cases, the weight average molecular weight may be from about 100 kDa to about 5000 kDa. In other cases, the weight average molecular weight may range from about 200 kDa to about 4000 kDa. In certain instances, the weight average molecular weight may be from about 250 kDa to about 3000 kDa.

[0047] The copolymers may have a controlled degree of isotacticity in the nitrile pendant groups. In some instances, at least 50 percent, at least 55 percent, at least 60 percent, at least 65 percent, at least 70 percent, at least 75 percent, at least 80 percent, at least 85 percent, or at least 90 percent of the nitrile pendant groups may be isotactic (meso-meso triad). In other cases, at least 60 percent of the nitrile pendant groups may be isotactic. In certain instances, at least 70 percent of the nitrile pendant groups may be isotactic.

[0048] The copolymers described herein may have a narrow molecular weight distribution. In some cases, the copolymer may have a dispersity (£)) of less than or equal to 1.25. The narrow dispersity may indicate a more uniform polymer structure.

[0049] The thermal properties of the copolymers may be influenced by the molecular weight and facticity . In some instances, the copolymer may have a glass transition temperature (Tg) between 90°C and 150°C. The decomposition temperature (Ta) of the copolymer may be between 250°C and 400°C in certain cases.

[0050] The combination of high molecular weight and controlled isotacticity may contribute to the thermal and mechanical properties of the resulting materials. These characteristics may be advantageous for various applications, including the production of carbon fibers with enhanced performance.

[0051] As described in the examples herein, atactic poly(t-butylacrylamide) (PTBAM) polymers, isotactic poly(t-butylacrylamide) (PTBAM) polymers, and atactic- isotactic PTBAM block copolymers may be produced. In some aspects, atactic PTBAM is formed by subjecting a mixture containing the TBAM monomers to a photochemical polymerization reaction using a xanthate iniferter and UV light as illustrated in FIG. 3. In various other aspects, isotactic PTBAM is formed by subjecting a mixture containing the TBAM monomers and a Lewis acid catalyst to a photochemical polymerization reaction using a xanthate iniferter and UV light as illustrated in FIG. 2A. In various additional aspects, the atactic-isotactic PTBAM block copolymers may be formed as illustrated in FIG. 8 by first forming atactic PTBAM by subjecting a mixture containing the TBAM monomers to a photochemical polymerization reaction using a xanthate iniferter and UV light, adding additional TBAM monomers and the Lewis acid catalyst to the atactic PTBAM mixture and subjecting to a second round of photochemical polymerization using the xanthate iniferter and UV light.

[0052] In other additional aspects, atactic ultra-high molecular weight poly(acrylamide-(t-butylacrylamide)) copolymers with molecular weights ranging from about 300 kDa to about 6M Da may be produced by subjecting a mixture containing acrylate and TBAM monomers to a photochemical polymerization reaction using a xanthate iniferter and UV light as illustrated in FIG. 5. In some aspects, similar ultra- high molecular weight poly(acrylamide-(t-butylacrylamide)) copolymers in isotactic configuration may be formed as described above by subjecting a mixture of acrylate and TBAM monomers plus the Lewis acid catalyst to a photochemical polymerization reaction using a xanthate iniferter and UV light. In various aspects, the resultingpoly(acrylamide-(t-butylacrylamide)) copolymers possess high molecular weight and sufficient solubility to render the polymers suitable for the production of high- performance carbon fibers as described herein.Method of Making Copolymers

[0053] The copolymers described herein may be prepared by a method comprising forming a reaction mixture, exposing the reaction mixture to visible or ultraviolet (UV) light, and dehydrating the resulting poly(alkyl acrylamide).

[0054] The reaction mixture may comprise an alkyl acrylamide, a rare earth metal trifluoromethanesulfonate (rare earth metal triflate), and a polymerization initiator. In some cases, the alkyl acrylamide may be iso-propyl acrylamide or tert-butyl acrylamide. In certain instances, the alkyl acrylamide may be tert-butyl acrylamide. Other examples of alkyl acrylamides that may be used include methyl acrylamide, ethyl acrylamide, n-propyl acrylamide, n-butyl acrylamide, iso-butyl acrylamide, and sec-butyl acrylamide.

[0055] The rare earth triflate in the reaction mixture may comprise one or more rare earth elements. Examples of rare earth triflates that may be used include yttnum inflate, scandium triflate, lanthanum triflate, cerium triflate, praseodymium triflate, neodymium triflate, samarium triflate, europium triflate, gadolinium triflate, terbium triflate, holmium triflate, erbium triflate, thulium triflate, ytterbium triflate, and lutetium Inflate. In some instances, the rare earth triflate may comprise yttrium triflate.

[0056] The polymerization initiator in the reaction mixture may be a free radical polymerization initiator, a controlled radical polymerization initiator, a cationic polymerization initiator, or an anionic polymerization initiator. In some cases, the polymerization initiator may be azobisisobutyronitrile (AIBN).

[0057] The reaction mixture may also include a solvent. In some instances, methanol may be used as the solvent for the polymerization reaction.

[0058] The reaction mixture may be exposed to ultraviolet (UV) light or visible light to form a poly(alkyl acrylamide). In some cases, the reaction mixture may be exposed to UV light at a temperature of less than or equal to 0°C. In certain instances, the reaction mixture may be exposed to UV light at a temperature of less than or equal to -20°C. The polymerization reaction may be carried out for a period of time, such as 3 days in some cases.

[0059] After the polymerization reaction, the resulting poly(alkyl acrylamide)may be punfied. In some instances, the polymer may be purified via dialysis against water.

[0060] The poly (alky 1 acrylamide) may then be dehydrated to form a copolymer comprising nitrile and alkyl amide pendant groups. The dehydration step may involve contacting the poly(alkyl acrylamide) with a dehydrating agent. In some cases, the poly(alkyl acrylamide) may be contacted with thionyl chloride (SOCb), phosphorus oxychloride (POCI3), or phosphorus pentoxide (P2O5) to dehydrate the poly(alkyl acrylamide). In certain instances, the poly(alkyl acrylamide) may be contacted with thionyl chloride (SOCI2).

[0061] The dehydration reaction may be carried out at an elevated temperature. In some cases, the poly(alkyl acrylamide) may be dehydrated at a temperature of from about 80°C to about 170°C. In other cases, the poly(alkyl acrylamide) may be dehydrated at a temperature of from about 80°C to about 130°C. The dehydration reaction may be earned out for a period of time, such as 24 hours in some instances.

[0062] The dehydration process may result in the conversion of alkyl amide groups to nitrile groups. In some cases, dehydrating the poly(alkyl acrylamide) may result in at least 80% conversion of the alkyl amide groups to nitrile groups. In other cases, the conversion may be at least 90%. In certain instances, the dehydration process may result in 100% conversion of the alkyl amide groups to nitrile groups.

[0063] The method described herein may allow for the preparation of copolymers with controlled tacticity and composition. By adjusting the reaction conditions and components, the properties of the resulting copolymers may be tuned for specific applications.

[0064] As shown herein, a method to develop the chemical process to produce precision PAN, having employed a photoinduced reversible addition-fragmentation chain-transfer (RAFT) polymerization to make low dispersity PTBAM weighing -200 and -1250 kDa is described. In the following Examples, infrared (IR) spectroscopy characterization data proves the irreversible chemical conversion of the amide groups to nitriles using excess thionyl chloride (SOCI2) was successful, as evidenced by the emergence of a -CN stretching peak at -2240 cm'1in the IR spectrum. Moreover, elemental analysis of the product PAN copolymer revealed a 70-84% range for conversion to nitrile groups, while NMR analysis corroborated the lower end of this range (-67%). These results are very encouraging, and higher conversion with further optimization of the chemical process can be achieved. Once optimized, the samechemical transformation can be done on PTBAM which is made with highly isotactic (i.e., stereo -defined side chains) in order to make the most structurally precise PAN ever made.

[0065] In various aspects, the Lewis acid catalyst used to facilitate the polymerization of the TBAM monomers into isotactic PTBAM polymers may be any suitable Lewis acid including, but not limited to yttrium triflate (Y (OT )?).

[0066] In various other aspects, the photochemical polymerization reaction may be conducted at a variety of conditions selected to enhance the rate and yield of the polymerization reaction. In some aspects, the wavelength of light used to illuminate the monomer solution may be any suitable wavelength including, but not limited to, a UV wavelength. Nonlimiting examples of suitable UV wavelengths for use in the photochemical polymerization reaction include 254 nm and 365 nm. In other aspects, the photochemical polymerization reaction may be conducted at a variety of temperatures ranging from about room temperature to about 0-4 °C. In some aspects, the photochemical polymerization reaction may be actively cooled using any suitable cooling method including, but not limited to, an ice water bath.

[0067] In various aspects, the various PTBAM polymers may be converted to corresponding polyacrylonitrile (PAN) polymers by mixing the precursor PTBAM polymer with a dehydration reaction agent to convert the amide moieties to nitrile moieties. Non-limiting examples of suitable dehydration agents include thionyl chloride (SOCI2), SOCh in combination with xylene, TFAA, AICI3, ZnCL, PBrs, oxalyl chlonde (COCI2), and any other suitable solvent or reagent. In an exemplary embodiment, the various PTBAM polymers may be converted to corresponding polyacrylonitrile (PAN) polymers by mixing the precursor PTBAM polymer with an excess of thionyl chloride (SOCI2).Preparation of Carbon Fibers

[0068] The copolymers described herein may be used to produce carbon fibers through a multi-step process. This process involves preparing a dope solution, spinning fibers, and thermal processing to convert the polymer fibers into carbon fibers.

[0069] To prepare the dope solution, the copolymer may be dissolved in a solvent such as dimethylformamide (DMF). In some cases, the concentration of the dope solution may be 10 weight percent (wt%) of the copolymer in DMF. The concentration of the dope solution may affect the properties of the resulting fibers.

[0070] The dope solution may then be used for fiber spinning. In some instances, the fiber spinning process may involve injecting the dope solution into a coagulation bath. The coagulation bath may comprise a mixture of water and methanol. In certain cases, the coagulation bath may consist of 85: 15 ThOMeOH by volume. The coagulation bath may be cooled to enhance fiber formation. In some instances, the coagulation bath may be cooled to 0°C.

[0071] The rate at which the dope solution is injected into the coagulation bath may affect the properties of the resulting fibers. In some cases, the fiber spinning injection rate may be 8 mL h’1. This controlled injection rate may help maintain consistent fiber properties.

[0072] After spinning, the fibers may undergo thermal processing to convert them into carbon fibers. This thermal processing may involve multiple stages with different temperature profiles.

[0073] In the first stage of thermal processing, the fibers may be treated in a muffle furnace. This step may help stabilize the fiber structure and prepare it for higher temperature treatment. In some instances, the fibers may be processed in a muffle furnace at 250°C for 1 hour. This treatment may initiate cyclization reactions in the polymer structure.

[0074] Following the muffle furnace treatment, the fibers may undergo further high-temperature processing in a tube furnace. This step may complete the carbonization process and develop the final carbon fiber structure. In some cases, the fibers may be processed in a tube furnace at 1500°C for 1 hour. The heating rate during this process may be controlled to optimize the carbon fiber properties. In certain instances, the heating rate for the tube furnace processing may be 10°C min'1.

[0075] The resulting carbon fibers may exhibit various properties that make them suitable for use in composite materials. These carbon fibers may demonstrate high strength, stiffness, and low weight, which are desirable characteristics for many applications.

[0076] The properties of the carbon fibers may be influenced by factors such as the initial copolymer composition, the fiber spinning conditions, and the thermal processing parameters. By adjusting these factors, the characteristics of the resulting carbon fibers may be tuned for specific applications.

[0077] Carbon fiber composite materials incorporating these fibers may offer advantages in terms of strength-to-weight ratio, stiffness, and other mechanicalproperties. These composites may find applications in aerospace, automotive, sporting goods, and other industries where high-performance materials are required.

[0078] The carbon fiber production process described herein may allow for the conversion of the copolymers into high-performance carbon fibers. The ability to control various parameters throughout the process may enable the production of carbon fibers with tailored properties for specific end-use applications.

[0079] The copolymers described herein comprise a unique combination of structural elements that work together to achieve desirable properties and functions. The composition, molecular weight, tacticity, and preparation method of these copolymers interact in complex ways to influence the characteristics of the resulting materials.

[0080] The copolymer composition, including the specific alkyl acrylamide monomers used and the ratio of different repeat units, may affect various properties of the material. For example, the choice of tert-butyl acrylamide as a monomer may contribute to the thermal stability of the copolymer due to the bulky tert-butyl groups. The ratio of nitrile to alkyl amide pendant groups in the final copolymer structure may influence properties such as solubility, reactivity , and mechanical strength.

[0081] The high molecular weight of the copolymers, ranging from about 20 kDa to about 5000 kDa, may contribute to improved mechanical properties and processability'. Higher molecular weight polymers typically exhibit greater strength and toughness due to increased chain entanglement and intermolecular forces. In some cases, the high molecular weight may also enhance the ability of the copolymer to form stable fibers during the spinning process.

[0082] The controlled tacticity of the copolymer, particularly the presence of isotactic (meso-meso triad) nitrile pendant groups, may play a crucial role in determining the material's properties. The isotactic arrangement of nitrile groups along the polymer backbone may promote more efficient packing of the chains, potentially leading to increased crystallinity and improved thermal stability. This structural feature may be particularly important during the thermal processing steps involved in carbon fiber production.

[0083] The preparation method of the copolymers, involving UV -initiated polymerization followed by a dehydration step, may allow for precise control over the final polymer structure. The low-temperature UV polymerization may help maintain the desired tacticity by minimizing side reactions or chain rearrangements. The subsequent dehydration step to convert alkyl amide groups to nitrile groups may be carefullycontrolled to achieve the desired ratio of functional groups while preserving the polymer's molecular weight and facticity.

[0084] The interaction of these various elements may result in copolymers with a unique combination of properties that make them well-suited for carbon fiber production. For instance, the high molecular weight and controlled facticity may contribute to the formation of strong, well-aligned polymer chains during fiber spinning. This alignment may be further enhanced during thermal processing, potentially leading to carbon fibers with improved mechanical properties.

[0085] During the thermal processing steps, the isotactic arrangement of nitrile groups may facilitate more efficient cyclization reactions, which are important for the formation of the graphitic structure in carbon fibers. The controlled composition and structure of the copolymer may allow for better control over these reactions, potentially resulting in carbon fibers with more uniform and desirable properties.

[0086] The combination of high molecular weight and controlled facticity may also contribute to the thermal stability of the copolymer during processing. This stability may allow for more controlled carbonization, potentially leading to carbon fibers with fewer defects and improved performance characteristics.

[0087] In some cases, the specific structural features of the copolymer may influence the interfacial properties of the resulting carbon fibers. For example, the presence of residual alkyl amide groups or partially converted nitrile groups on the fiber surface may affect the fiber's ability to bond with matrix materials in composite applications.

[0088] The interaction between the copolymer's composition, structure, and preparation method may also impact the processability of the material. For instance, the balance between nitrile and alkyl amide groups may affect the solubility of the copolymer in various solvents, which may in turn influence the preparation of spinning dopes and the fiber formation process.

[0089] In summary, the various elements of the copolymer work together in complex ways to determine its properties and function. The careful control of composition, molecular weight, facticity, and preparation method may allow for the production of copolymers tailored for specific applications, particularly in the field of high-performance carbon fibers. The interactions between these elements may contribute to the unique characteristics of the resulting materials, potentially offering advantages in terms of mechanical properties, thermal stability, and processability compared toconventional polyacrylonitrile-based precursors.

[0090] In some aspects, the present disclosure establishes a wet spinning and thermal processing workflow that enables the fabrication of pre-fiber filaments, which is followed by heat curing this precursor to make CFs and testing its elastic moduli (E) and tensile strength. The higher molar mass PAN alone can show greater stiffness and tensile strength in comparison to existing commercial CFs. In other aspects, CFs comprising “precision” PAN copolymer with isotactic side-chain groups are simultaneously described. Lastly, there are many sources of commercially available PAN and CF-based composites that can be compared to the described CFs and related materials, thus serving as a quantifiable benchmark. These research efforts lead to a completely different approach to synthesizing low dispersity, high MW, and stereo-defined “precision PAN” that can lead to higher performance CFs and wider adoption overall due to lower costs for less material needed.

[0091] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 wt.%” is intended to mean “about 40 wt.%”.

[0092] Examples of CFs are described herein. CFs can be, copolymers of the formula:R groups can be optionally substituted with one or more groups independently selected from the group consisting of hydroxyl; C noalkyl hydroxyl; amine; Ci- locarboxylic acid; Ci-iocarboxyl; straight chain or branched C i-ioalkyl, optionally containing unsaturation; a C2-iocycloalkyl optionally containing unsaturation or one oxygen or nitrogen atom; straight chain or branched C i-ioalkyl amine; heterocyclyl; heterocyclic amine; and aryl comprising a phenyl; heteroaryl containing from 1 to 4 N, O, or S atoms; unsubstituted phenyl ring; substituted phenyl ring; unsubstituted heterocyclyl; and substituted heterocyclyl, wherein the unsubstituted phenyl ring orsubstituted phenyl ring can be optionally substituted with one or more groups independently selected from the group consisting of hydroxyl; Ci-ioalkyl hydroxyl; amine; Ci-iocarboxyhc acid; Ci-iocarboxyl; straight chain or branched Ci-ioalkyl, optionally containing unsaturation; straight chain or branched C i-ioalkyl amine, optionally containing unsaturation; a C2-iocycloalkyl optionally containing unsaturation or one oxygen or nitrogen atom; straight chain or branched Ci-ioalkyl amine; heterocyclyl; heterocyclic amine; aryl comprising a phenyl; and heteroaryl containing from 1 to 4 N, 0, or S atoms; and the unsubstituted heterocyclyl or substituted heterocyclyl can be optionally substituted with one or more groups independently selected from the group consisting of hydroxyl; Ci-ioalkyl hydroxyl; amine; Ci- locarboxylic acid; Ci-iocarboxyl; straight chain or branched Ci-ioalkyl, optionally containing unsaturation; straight chain or branched C i-ioalkyl amine, optionally containing unsaturation; a C2-iocycloalkyl optionally containing unsaturation or one oxygen or nitrogen atom; heterocyclyl; straight chain or branched C i-ioalkyl amine; heterocyclic amine; and aryl comprising a phenyl; and heteroaryl containing from 1 to 4 N, 0, or S atoms. Any of the above can be further optionally substituted.Definitions

[0093] The term “imine” or “imino”, as used herein, unless otherwise indicated, can include a functional group or chemical compound containing a carbon-nitrogen double bond. The expression “imino compound”, as used herein, unless otherwise indicated, refers to a compound that includes an “imine” or an “imino” group as defined herein. The “imine” or “imino” group can be optionally substituted.

[0094] The term “hydroxyl”, as used herein, unless otherwise indicated, can include -OH. The “hydroxyl” can be optionally substituted.

[0095] The terms “halogen” and “halo”, as used herein, unless otherwise indicated, include chlorine, chloro, Cl; fluorine, fluoro, F; bromine, bromo, Br; or iodine, iodo, or I.

[0096] The term “acetamide”, as used herein, is an organic compound with the formula CH3CONH2. The “acetamide” can be optionally substituted.

[0097] The term “aryl”, as used herein, unless otherwise indicated, includes a carbocyclic aromatic group. Examples of aryl groups include, but are not limited to, phenyl, benzyl, naphthyl, or anthracenyl. The “aryl” can be optionally substituted.

[0098] The terms “amine” and “amino”, as used herein, unless otherwiseindicated, include a functional group that contains a nitrogen atom with a lone pair of electrons and wherein one or more hydrogen atoms have been replaced by a substituent such as, but not limited to, an alkyl group or an aryl group. The “amine” or “amino” group can be optionally substituted.

[0099] The term “alkyl”, as used herein, unless otherwise indicated, can include saturated monovalent hydrocarbon radicals having straight or branched moieties, such as but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl groups, etc. Representative straight-chain lower alkyl groups include, but are not limited to, -methyl, -ethyl, -n-propyl, -n-butyl, -n-pentyl, -n-hexyl, -n-heptyl and -n-octyl; while branched lower alkyl groups include, but are not limited to, -isopropyl, -sec-butyl, -isobutyl, -tert- butyl, -isopentyl, 2-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3- dimethylbutyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 3,3-dimethylpentyl, 2,3,4- tnmethylpentyl, 3-methylhexyl, 2,2-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3,5-dimethylhexyl, 2,4-dimethylpentyl, 2-methylheptyl, 3-methylheptyl, unsaturated Ci-io alkyls include, but are not limited to, -vinyl, -allyl, -1-butenyl, -2- butenyl, -isobutylenyl, -1-pentenyl, -2-pentenyl, -3-methyl-l-butenyl, -2-methyl-2- butenyl, -2,3-dimethyl-2-butenyl, 1 -hexyl, 2-hexyl, 3-hexyl, -acetylenyl, -propynyl, -1- butynyl, -2-butynyl, -1 -pentynyl, -2-pentynyl, or -3-methyl-l butynyl. An alkyl can be saturated, partially saturated, or unsaturated. The “alkyl” can be optionally substituted.

[0100] The term “carboxyl”, as used herein, unless otherwise indicated, can include a functional group consisting of a carbon atom double bonded to an oxygen atom and single bonded to a hydroxyl group (-COOH). The “carboxyl” can be optionally substituted.

[0101] The term “alkenyl”, as used herein, unless otherwise indicated, can include alkyl moieties having at least one carbon-carbon double bond wherein alkyl is as defined above and including E and Z isomers of said alkenyl moiety. An alkenyl can be partially saturated or unsaturated. The “alkenyl” can be optionally substituted.

[0102] The term “alkynyl”, as used herein, unless otherwise indicated, can include alkyl moieties having at least one carbon-carbon triple bond wherein alky l is as defined above. An alkynyl can be partially saturated or unsaturated. The “alkynyl” can be optionally substituted.

[0103] The term “acyl”, as used herein, unless otherwise indicated, can include a functional group derived from an aliphatic carboxylic acid, by removal of the hydroxyl (-OH) group. The “acyl” can be optionally substituted.

[0104] The term “alkoxy!” as used herein, unless otherwise indicated, can include O-alkyl groups wherein alkyl is as defined above and 0 represents oxygen. Representative alkoxyl groups include, but are not limited to, -O-methyl, -O-ethyl, -O-n- propyl, -O-n-butyl, -O-n-pentyl, -O-n-hexyl, -O-n-heptyl, -O-n-octyl, -O-isopropyl, -0- sec-butyl, -O-isobutyl, -O-tert-butyl, -O-isopentyl, -O-2-methylbutyl, -0-2 -methylpentyl, -0-3 -methylpentyl, -0-2,2-dimethylbutyl, -0-2,3-dimethylbutyl, -0-2,2-dimethylpentyl, -0-2,3-dimethylpentyl, -0-3,3-dimethylpentyl, -0-2,3,4-trimethylpentyl, -0-3- methylhexyl, -0-2,2-dimethylhexyl, -0-2,4-dimethylhexyl, -0-2,5-dimethylhexyl, -0- 3,5-dimethylhexyl, -O-2,4dimethylpentyl, -0-2-methylheptyl, -0-3-methylheptyl, -0- vinyl, -O-allyl, -0-1-butenyl, -0-2-butenyl, -O-isobutylenyl, -0-1 -pentenyl, -0-2- pentenyl, -0-3 -methyl- 1-butenyl, -O-2-methyl-2-butenyl, -O-2,3-dimethyl-2-butenyl, - 0-1-hexyl, -0-2-hexyl, -0-3-hexyl, -O-acetylenyl, -O-propynyl, -0-1-butynyl, -0-2- butynyl, -0-1 -pentynyl, -0-2-pentynyl and -0-3-methyl-l-butynyl, -O-cyclopropyl, -0- cyclobutyl, -O-cyclopentyl, -O-cyclohexyl, -O-cycloheptyl, -O-cyclooctyl, -0- cyclononyl and -O-cyclodecyl, -O-CEE-cyclopropyl, -O-CEE-cyclobutyl, -O-CH2- cyclopentyl, -O-CEE-cyclohexyl, -O-CEh-cycloheptyl, -O-CH2-cyclooctyl, -0- CH2- cyclononyl, -O-CEE-cyclodecyl, -O-(CH2)2-cyclopropyl, -O-(CH2)2-cyclobutyl, -0- (CEE^-cyclopentyl, -O-(CH2)2-cyclohexyl, -O-(CH2)2-cycloheptyl, -O-(CH2)2- cyclooctyl, -O-(CH2)2-cyclononyl, or -O-(CH2)2-cyclodecyl. An alkoxyl can be saturated, partially saturated, or unsaturated. The “alkoxyl” can be optionally substituted.

[0105] The term “cycloalkyl”, as used herein, unless otherwise indicated, can include an aromatic, a non-aromatic, saturated, partially saturated, or unsaturated, monocyclic or fused, spiro or unfused bicyclic or tricyclic hydrocarbon referred to herein containing a total of from 1 to 10 carbon atoms (e.g., 1 or 2 carbon atoms if there are other heteroatoms in the ring), preferably 3 to 8 ring carbon atoms. Examples of cycloalkyls include, but are not limited to, C3-10 cycloalkyl groups include, but are not limited to, -cyclopropyl, -cyclobutyl, -cyclopentyl, -cyclopentadienyl, -cyclohexyl, - cyclohexenyl, -1,3-cyclohexadienyl, -1,4-cyclohexadienyl, -cycloheptyl, -1,3- cycloheptadienyl, -1,3,5-cycloheptatrienyl, -cyclooctyl, and -cyclooctadienyl. The term “cycloalkyl” also can include -lower alkyl-cycloalkyl, wherein lower alkyd and cycloalkyl are as defined herein. Examples of -lower alkyl-cycloalkyl groups include, but are not limited to, -CEE-cyclopropyl, -CEE-cyclobutyl, -CEE-cyclopentyl, -CH2- cyclopentadienyl, -CEE-cyclohexyl, -CEE-cycloheptyl, or -CEh-cyclooctyl. The“cycloalkyl” can be optionally substituted. A “cycloheteroalkyl”, as used herein, unlessotherwise indicated, can include any of the above with a carbon substituted with a heteroatom (e.g., 0, S, N).

[0106] The term “heterocyclic” or “heteroaryl”, as used herein, unless otherwise indicated, can include an aromatic or non-aromatic cycloalkyl in which one to four of the ring carbon atoms are independently replaced with a heteroatom from the group consisting of 0, S and N. Representative examples of a heterocycle include, but are not limited to, benzofuranyl, benzothiophene, indolyl, benzopyrazolyl, coumarinyl, isoquinolinyl, pyrrolyl, pyrrolidinyl, thiophenyl, furanyl, thiazolyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, pyrimidinyl, pyridinyl, pyridonyl, pyrazinyl, pyridazinyl, isothiazolyl, isoxazolyl, (l,4)-di oxane, (1 ,3)-di oxolane, 4,5-dihydro-lH-imidazolyl, or tetrazolyl. Heterocycles can be substituted or unsubstituted. Heterocycles can also be bonded at any ring atom (i.e., at any carbon atom or heteroatom of the heterocyclic ring). A heterocyclic can be saturated, partially saturated, or unsaturated. The “hetreocyclic” can be optionally substituted.

[0107] The term “indole”, as used herein, is an aromatic heterocyclic organic compound with the formula GH?N. It has a bicyclic structure, consisting of a sixmembered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. The “indole” can be optionally substituted.

[0108] The term “cyano”, as used herein, unless otherwise indicated, can include a -CN group. The “cyano” can be optionally substituted.

[0109] The term “alcohol”, as used herein, unless otherwise indicated, can include a compound in which the hydroxyl functional group (-OH) is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms. The “alcohol” can be optionally substituted.

[0110] The term “solvate” is intended to mean a solvate form of a specified compound that retains the effectiveness of such a compound. Examples of solvents include compounds of the invention in combination with, for example: water, isopropanol, ethanol, methanol, dimethylsulfoxide (DMSO), ethyl acetate, acetic acid, or ethanolamine.[oni] The term “mmol”, as used herein, is intended to mean millimole. The term “equiv”, as used herein, is intended to mean equivalent. The term “mL”, as used herein, is intended to mean milliliter. The term “g”, as used herein, is intended to mean gram. The term “kg”, as used herein, is intended to mean kilogram. The term “pg”, as used herein, is intended to mean micrograms. The term “h”, as used herein, is intended tomean hour. The term “min”, as used herein, is intended to mean minute. The term “M”, as used herein, is intended to mean molar. The term "pL", as used herein, is intended to mean microliter. The term “pM”, as used herein, is intended to mean micromolar. The term “nM”, as used herein, is intended to mean nanomolar. The term “N”, as used herein, is intended to mean normal. The term “amu”, as used herein, is intended to mean atomic mass unit. The term “°C”, as used herein, is intended to mean degree Celsius. The term “wt / wt”, as used herein, is intended to mean weight / weight. The term “v / v”, as used herein, is intended to mean volume / volume. The term “MS”, as used herein, is intended to mean mass spectroscopy. The term “HPLC”, as used herein, is intended to mean high- performance liquid chromatography. The term “RT”, as used herein, is intended to mean room temperature. The term "e.g.", as used herein, is intended to mean example. The term “N / A”, as used herein, is intended to mean not tested.

[0112] As used herein, the expression “pharmaceutically acceptable salt” refers to pharmaceutically acceptable organic or inorganic salts of a compound of the invention. Preferred salts include, but are not limited, to sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p- toluenesulfonate, or pamoate (i.e., l,l'-methylene-bis-(2-hydroxy-3-naphthoate)) salts. A pharmaceutically acceptable salt may involve the inclusion of another molecule such as an acetate ion, a succinate ion, or other counterion. The counterion may be any organic or inorganic moiety that stabilizes the charge on the parent compound. Furthermore, a pharmaceutically acceptable salt may have more than one charged atom in its structure. Instances where multiple charged atoms are part of the pharmaceutically acceptable salt can have multiple counterions. Hence, a pharmaceutically acceptable salt can have one or more charged atoms and / or one or more counterion. As used herein, the expression “pharmaceutically acceptable solvate” refers to an association of one or more solvent molecules and a compound of the invention. Examples of solvents that form pharmaceutically acceptable solvates include, but are not limited to, water, isopropanol, ethanol, methanol, DMSO, ethyl acetate, acetic acid, and ethanolamine. As used herein, the expression “pharmaceutically acceptable hydrate” refers to a compound of the invention, or a salt thereof, that further can include a stoichiometric or non- stoichiometric amount of water bound by non-covalent intermolecular forces.

[0113] Having described the embodiments in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.EXAMPLES

[0114] The following non-limiting examples are provided to further illustrate the present disclosure. It should be appreciated by those of skill in the art that the techniques disclosed in the examples that follow represent approaches the inventors have found function well in the practice of the present disclosure and thus can be considered to constitute examples of modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific instances that are disclosed and still obtain a like or similar result without departing from the spirit and scope of the present disclosure.Example 1 : Development of copolymers

[0115] To address this gap, we describe here a method by which iPAN was prepared as a copolymer via a two-step chemical process (Figure 1 A) that begins with Lewis acid-catalyzed stereocontrolled polymerization of A-tert-butylacrylamide (TBAM), followed by a post-polymerization modification15’16involving a pseudodehydration step with the reagent SOCb that converted the acrylamide groups to nitriles.17The byproducts from this reaction are SO2, HC1, and isobutylene, all gases that are easily removed via an inert N2 gas line, meaning the reactions are essentially irreversible. The presence or absence of the Lewis acid yielded high molecular weight and low dispersity isotactic or atactic PTBAM, both of which were converted into the corresponding iPAN-TB and aPAN-TB copolymers. These copolymers, along with commercially available PAN, were wet spun and thermally processed in muffle (250 °C) and tube (1500 °C) furnaces to yield carbon fibers. The pre- and post-muffle furnace fibers were then evaluated through tensile tests to establish structure-property- performance relationships as a function of copolymer composition and stereochemistry. The results from these studies revealed that aPAN-TB had the highest overall tensile modulus and strength, yet iPAN-TB's tensile modulus and strength increased six- and five-fold, respectively, upon heating while also counterintuitively becoming more elastic.

[0116] Prior to making iPAN copolymer, the stereocontrolled polymerization step was first tested on A-isopropyl acrylamide (NIP AM), following an existingliterature procedure.18The synthesis of isotactic and atactic poly (NIP AM) (i.e., iPNIPAM and aPNIPAM, respectively) was carried out at -20 °C in MeOH using UV light and azobisisobutyronitrile (AIBN) to initiate the polymerization in the presence or absence of Y(OTf 3 over the course of 3 d. Control over the corresponding stereochemistry was confirmed by comparing theJH NMR spectra of each polymer postworkup (Figure 2 and Figure 3) to that of the published spectra for iPNIPAM and aPNIPAM. Once confirmed, the same protocol was used to synthesize iPTBAM and aPTBAM from TBAM monomer, with and without Y(OTf)3 present, respectively, because attempts to convert PNIPAM to PAN copolymers did not yield nitrile groups, but rather what appeared to be carboxylic acids (as determined by IR spectroscopy).

[0117] Conversion of the PTBAM polymers to the corresponding PAN-TB copolymers was performed by dissolving the starting material in neat SOCh and heating the reaction to 100 °C for 24 h. After completion, the crude mixture was quenched over an ice bath and washed further with H2O. The transformation of N- / c / 7-butylaciylamide subunits to acry lonitrile groups was confirmed using IR spectroscopy (Figure IB), whereby the presence of the diagnostic nitrile stretch at -2200 cm1combined with a decrease in the amide N-H absorption peak around 3400 cm1indicated a successful functional group transformation. Analytical gel permeation chromatography (GPC) traces and the corresponding molecular weight data were obtained (Figure 1C, Table 1, and Figure 4) for each PTBAM precursor polymer and PAN-TB copolymer. Both iPTBAM and aPTBAM were found to be low dispersity precursors (Mn= 174.9 kDa, Mw= 195.4 kDa, £> = 1.12 and = 112.7 kDa, Mw= 138.9 kDa and £> = 1.23, respectively). The breadth of the GPC peaks after conversion to the PAN-TB copolymers did not change much; an indication that their molecular weight distributions were preserved (iPAN-TB: M„ = 176.9 kDa, Mw= 210.9 kDa and £> = 1.19 and aPAN-TB: M„ = 437.5 kDa, Mw= 506.6 kDa, £> = 1.16). In contrast, the commercial PAN sample from Sigma- Aldrich had a much broader molecular weight distribution (Mn= 51.8 kDa, Mw= 131.2 kDa, D = 2.53). It should also be noted that the increase in molecular weight for aPAN- TB is the result of some aggregation in the 10 wt% dope solution that was used for wet spinning and from which the GPC data was obtained. The same increase was not present for iPAN-TB because a 10 wt% solution was not achieved (vide infra).Table 1. Polymer Molecular Weights, Dispersity, and Thermal Transition Data.

[0118] The percent conversion for the dehydration reaction was calculated using the integrations from the corresponding NMR spectra (Figure 5A-B, Figure 6). Specifically, the proton resonance just above 3.0 ppm was identified as the CH proton alpha to the nitrile group on the polymer backbone by comparing the1H NMR spectra of commercial Sigma PAN and the aPAN-TB sample (Figure 5A). Next, a comparison between this proton resonance and that of the / -butyl group (Figure 5B) revealed the post-polymerization conversion process was 78% effective. To determine the facticity of Sigma PAN, aPAN-TB, and iPAN-TB,13C NMR spectroscopy was used (Figure 5C). The stereochemical assignments (mm, mr, or rr) were made using Sigma PAN as a control and previous analysis from the literature,7primarily focusing on the region around 120.0 ppm (see dashed box in Figure 5C). This analysis revealed commercial Sigma PAN exhibited 30% mm triads, aPAN-TB consisted of 35% mm triads, and iPAN- TB consisted of 77% mm triads, representing one of the highest isotacticities for PAN to date.

[0119] Each polymer’s thermophysical properties were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results from these experiments showed (Table 1) that Sigma PAN exhibited a glass transition (Tg) at 95.8 °C and decomposition temperature (Ta) at 292.9 °C. In contrast, aPAN-TB exhibited a Tg= 118.8 °C and a Ta = 286.8 °C versus iPAN-TB at Tg= 132.0 °C and Ta = 298.0 °C. The higher Tgvalue for iPAN-TB versus the other two suggests tighter packing and thus stronger interchain interactions in the bulk samples as a function of the more stereodefmed backbone.19'21The lower Ta value for aPAN-TB versus iPAN- TB also suggests decomposition of the TBAM subunits that are not as tightly packedtogether in the solid state as they are with 1PAN-TB.

[0120] Next, dope solutions were prepared for each polymer at 10 wt% in dimethylformamide (DMF) to make fibers. This concentration was chosen as it yielded the best fibers during wet spinning. To prepare these solutions, the solid PAN samples were slowly added into the DMF solution to prevent aggregation and improve dissolution. The solutions were sonicated and stirred for up to a week until they became fully homogeneous. It is important to note that this protocol resulted in the complete dissolution of the Sigma PAN and aPAN-TB samples, however, the iPAN-TB solution contained gelatinous aggregates that did not fully dissolve. These aggregates were recovered after the dissolved portion was removed for wet spinning into fibers. Subtraction of the corresponding mass of the dried aggregates from the total amount of iPAN-TB sample that was added resulted in a final concentration of the dope solution that was closer to ~4-5 wt%. Even at this lower concentration, the iPAN-TB-derived fibers exhibited a significant increase in mechanical properties after thermal processing (vide infra).

[0121] Upon slow injection of each dope solution from a 10 mL syringe connected to a syringe pump operating at 8.0 mL h-1, the polymer formulation began precipitating in the coagulation bath consisting of 85: 15 FECkMeOH. These early gelatinous precipitates were clasped using forceps and pulled manually along the coagulation bath until reaching the automated spindles that helped with additional pulling and stretching of the pre-fiber. This process yielded several feet of fiber consisting of each precursor polymer that was subsequently washed in an inline H2O bath before being dried by an inline heater set at 100 °C. Next, the several feet-long fiber samples were hung in a fume hood to dry overnight.

[0122] The following day, each fabricated fiber was broken into 4-5 in segments so they could be placed in an alumina crucible and thermally processed in a muffle furnace (i.e., stabilization). Modifying a known literature protocol,22the muffle furnace was heated to 250 °C in 50 min followed by holding it at 250 °C for 1 h under ambient conditions. This stabilization step is necessary to oxidize and induce intramolecular ring closing (Figure 7A) and intermolecular crosslinking through the pendant nitrile groups, resulting in a stiffer, more crystalline fiber. Scanning electron microscopy (SEM) was used to analyze the dimensions and morphology of the post-muffle fibers. Figures 7B-D show the as-spun fibers in order of Sigma PAN, aPAN-TB, and iPAN-TB, respectively. Figures 7E-G show the corresponding fibers after they were processed in the mufflefurnace. There are distinct differences in fiber diameter and texture, as shown in the SEM images. Specifically, Sigma PAN yielded smoother as-spun and post-muffle furnace fibers, whereas the aPAN-TB and iPAN-TB samples had a rougher surface texture for the as-spun fibers as well as a somewhat porous morphology after the fibers were heated in the muffle furnace. Moreover, it is clear that the lower wt% dope solution for iPAN- TB yielded thinner fibers (248.4 pm vs. 537.6 and 267.7 pm for the as-spun Sigma PAN and aPAN-TB fibers; 188.0 um vs. 311.7 and 210.4 for the post-muffle furnace Sigma PAN and aPAN-TB fibers, respectively). Additional thermal processing in a tube furnace held at 1 00 °C for 1 h (with a 10 °C min-1ramp up) was performed for each group of fibers, however, only the as-spun and muffle furnace fibers underwent tensile testing as the post-tube furnace fibers were too brittle.Table 2. Mechanical Properties and Performance Metrics of Fabricated Carbon Fibers

[0123] Tensile tests were performed (Figure 8A-C, Table 2) on the as-spun (as) and post-muffle furnace (m) fibers by gluing short 1.0-1.5 in segments to paper squares which the tensile instrument clamps latched onto. Sigma PAN (as) exhibited an average tensile strength (TS) of 1.49 MPa, an average tensile (Y oung’s) modulus (E) of 0.32 MPa, and an average elongation at break (e) at 5.89%. After processing the fibers in the muffle furnace, these values changed to TS = 2.85 MPa, E = 1.97 MPa, and e = 2.17%. The key takeaways from this data are that the fibers became stronger (1.9x) and stiffer (6.2x) but less elastic (0.4x) after being stabilized in the muffle furnace. For aPAN-TB (as), the average performance metrics were TS = 6.12 MPa, E = 3. 16 MPa, and e = 2.56% versus TS = 10. 17 MPa, E = 5. 18 MPa, and e = 2.93% for the correspondingmuffle furnace-processed fibers aPAN-TB (m). Surprisingly, all metrics increased in terms of strength (1.7x), stiffness (1.6x), and elasticity (1.2x), but not to the same extent as the Sigma PAN-based fibers. We hypothesize that the counterintuitive increase in both the stiffness and elasticity of aPAN-TB-derived fibers occurred as a function of the bulkier / -butyl groups on the non-converted acrylamide subunits, which effectively facilitated interchain disruption while the fibers were placed under tension.

[0124] However, the observed fold changes for the aPAN-TB fibers were incomparable to the changes observed for iPAN-TB fibers pre- and post-muffle furnace (Table 2). Specifically, the iPAN-TB (as) values were found to be TS = 1.23 MPa, E = 0.40 MPa, and e = 4.08% versus the iPAN-TB (m) values TS = 7.52 MPa, E = 2.07 MPa, and i: = 5.62%. The post-stabilization data for iPAN-TB (m) represents a significant increase in all three performance categories, where strength (6. lx), stiffness (5.2x), and elasticity (1.4x) were enhanced the most out of all fibers tested in this investigation. The key hypothesis based on this data is that the stabilization process at 250 °C was more efficient on account of the higher degree of isotacticity in the polymer backbone and thus the more favorable spatial arrangement of the pendant nitrile groups. The significance of this result is further amplified by the fact that a less concentrated dope solution was used to fabricate the iPAN-TB fibers (~4-5 wt%) versus the other two sets (10 wt%) due to solubility issues. The lower concentration of the dope solution also explains why the absolute values for TS and E were less than those for aPAN-TB. All the TS and E values for each type of fiber are summarized in the plot shown in Figure 8D to better visualize the changes in performance pre- and post-muffle fumace / stabilization. Future work in this area will focus on developing a more efficient dissolution protocol for iPAN-TB such that a final 10 wt% solution can be prepared homogenously, and the overall properties and performance directly compared to the performance of fibers derived from Sigma PAN and aPAN-TB copolymers.

[0125] In conclusion, a new two-step chemical process is reported that represents a novel way to make high molecular weight, low dispersity, and atactic (30% mm triads) or highly isotactic (77% mm triads) PAN-based copolymers for the purpose of fabricating carbon fibers. The key step in the synthesis utilized an irreversible PPM reaction involving the reagent SOCh that converted 78% A-zcrz-butylaciylamides into nitrile groups. The resultant carbon fibers showed enhanced properties over carbon fibers derived from commercial PAN. Specifically, a higher tensile strength and moduli were obtained overall for the aPAN-TB copolymer and the greatest amount of change afterthermal processing at 250 °C was observed for iPAN-TB copolymer, whereby the corresponding carbon fiber’s strength and modulus (i.e., stiffness) increased 6- and 5- fold, respectively, while its elasticity increased -38% relative to its as-spun precursor fiber. Future efforts with this research will focus on obtaining higher isotacticities, higher PPM conversion efficiencies, and a dissolution protocol for the iPAN-TB copolymer that allows for a homogeneous dope solution at 10 wt% like the aPAN-TB and commercial PAN copolymers.REFERENCES1. Newcomb, B. A., Processing, structure, and properties of carbon fibers. Compos. - A: Appl. Set. Manuf. 2016, 97, 262-282.2. Kaur, J.; Millington, K; Smith, S., Producing high-quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review. J. Appl. Polym. Set. 2016, 133 (38).3. Ghorpade, R. V.; Lee, S.; Hong, S. C., Effect of different itaconic acid contents of poly(acrylonitrile-co-itaconic acid)s on their carbonization behaviors at elevated temperatures. Polym. Degrad. Stab. 2020, 181, 109373.4. Bashir, Z., A critical review of the stabilisation of polyacrylonitrile. Carbon 1991, 29 (8), 1081-1090.5. Peijs, T.; Kirschbaum, R.; Lemstra, P. J., Chapter 5: A critical review of carbon fiber and related products from an industrial perspective. Adv. Ind. Eng. Polym. Res. 2022, 5 (2), 90-106.6. Ghorpade, R. V.; Cho, D. W; Hong, S. C., Effect of controlled tacticity of polyacrylonitrile (co)polymers on their thermal oxidative stabilization behaviors and the properties of resulting carbon films. Carbon 2017, 727, 502-511.7. Hao, J.; Li, W.; Suo, X.; Wei, H.; Lu, C.; Liu, Y, Highly isotactic (>60%) polyacrylonitrile-based carbon fiber: Precursor synthesis, fiber spinning, stabilization and carbonization. Polymer 2018, 757, 139-150.8. Rwei, S.-P.; Way, T.-E; Chiang, W.-Y; Pan, S.-Y, Effect oftacticity on the cyclization of polyacrylonitrile copolymers. Colloid Polym. Sei. 2017, 295 (5), 803-815.9. Love-Baker, C. A.; Harrell, T. M.; Vautard, E; Klett, J.; Li, X., Analysis of the turbostratic structures in PAN-based carbon fibers with wide-angle x-ray diffraction. Carbon 2024, 224, 119037.10. Lewandowska, A. E.; Soutis, C.; Savage, L.; Eichhorn, S. J., Carbon fibres with ordered graphitic-like aggregate structures from a regenerated cellulose fibre precursor. Compos. Sci. Technol. 2015, 116, 50-57.11. Kopec, M.; Krys, P.; Yuan, R.; Matyjaszewski, K, Aqueous RAFT Polymerization of Acrylonitrile. Macromolecules 2016, 49 (16), 5877-5883.12. Wang, Y; Nakamura, R.; Suga, T; Li, S.; Ohki, Y; Nishide, H ; Oyaizu, K, Facile Synthesis of Isotactic Polyacrylonitrile via Template Polymerization in Interlayer Space for Dielectric Energy Storage. ACS Appl. Polym. Mater. 2020, 2 (2), 775-781.13. Lutz, J.-F.; Jakubowski, W; Matyjaszewski, K, Controlled / Living Radical Polymerization of Methacrylic Monomers in the Presence of Lewis Acids: Influence on Tacticity. Macromol. Rapid Commun. 2004, 25 (3), 486-492.14. Ray, B.; Isobe, Y; Morioka, K; Habaue, S.; Okamoto, Y; Kamigaito, M.; Sawamoto, M., Synthesis of Isotactic Poly(N-isopropylacrylamide) by RAFT Polymerization in the Presence of Lewis Acid. Macromolecules 2003, 36 (3), 543-545.15. Gauthier, M. A.; Gibson, M. I.; Klok, H.-A., Synthesis of Functional Polymers by Post-Polymerization Modification. Angew. Chem., Int. Ed. 2009, 48 (1), 48-58.16. Chen, X.; Michinobu, T., Postpolymerization Modification: A Powerful Tool for the Synthesis and Function Tuning of Stimuli-Responsive Polymers. Macromol. Chem. Phys. 2022, 223 (1), 2100370.17. Ganesan, M.; Nagaraaj, P., Recent developments in dehydration of primary amides to nitriles. Org. Chem. Front. 2020, 7 (22), 3792-3814.18. Isobe, Y; Fujioka, D.; Habaue, S.; Okamoto, Y, Efficient Lewis Acid-Catalyzed Stereocontrolled Radical Polymerization of Acrylamides. J. Am. Chem. Soc. 2001, 123 (29), 7180-7181.19. Privalko, V. P; and Lipatov, Y. S., Glass transition and chain flexibility' of linear polymers. J. Macromol. Sci., Part B 1974, 9 (3), 551-564.20. Dudowicz, J.; Freed, K. F.; Douglas, J. F., The Glass Transition Temperature of Polymer Melts. J. Phys. Chem. B 2005, 109 (45), 21285-21292.21. Pankaj, S.; Hempel, E.; Beiner, M., Side-Chain Dynamics and Cr stallization in a Series of Regiorandom Poly(3-alkylthiophenes). Macromolecules 2009, 42 (3), 716- 724.22. Li, J.; Hu, C.; Wang, Y-Y; Meng, X.; Xiang, S.; Bakker, C.; Plaza, K.; Ragauskas, A. J.; Dai, S. Y; Yuan, J. S., Lignin molecular design to transform green manufacturing. Matter 2022, 5 (10), 3513-3529.MATERIALS / GENERAL METHODS / INSTRUMENTATION

[0126] All reagents were purchased from commercial suppliers. N- isopropylacrylamide and A-tert-butylacrylamide monomers were purified via a silica plug, and AIBN was purified via recrystallization from MeOH. All reactions were performed under nitrogen (N2) or argon (Ar) gas unless otherwise stated. All nuclear magnetic resonance (NMR) spectra were recorded on Varian Inova-500 spectrometer at 25 °C - 75°C, with working frequencies of 500 H) and 125 (13C) MHz. Chemical shifts are reported in ppm relative to the signals corresponding to the residual non-deuterated solvents: CDCh: 8H = 7.26 ppm and 8c = 77. 16 ppm; (CDs SO: 8H = 2.50 ppm and 8c = 39.52 ppm. Analytical GPC analyses were performed on an Agilent 1260 Infinity setup with two Shodex GPC KD-806M columns in sequence in DMF mobile phase (0.025 M LiBr) running at 60 °C at a 1.0 mL*min1flow rate. The differential refractive index (dRI) of each compound was monitored using a Wyatt Optilab T-rEX detector. Infrared spectroscopy was preformed using a ThermoScientific Nicolet Summit X FTIR spectrometer with an Everest ATR module. Differential scanning calorimetry was performed using a TA instruments 2500 Discovery system with TO aluminum DSC pans. Thermogravimetric analysis was performed with a TA Instruments Q5000 system with Platinum 100 pL TGA pan. Fibers were fabricated using a AME-WSM Professional Laboratory Equipment Desktop Wet Spinning Machine, equipped with a cooledcoagulation bath, a wash bath, three traction spinning machines, and an inline heater. Fibers were processed in a MTI KSL-1200X-L Muffle Furnace and a MTI GSL1600X50 Tube Furnace equipped with an alumina tube. Scanning electron microscopy (SEM) was conducted using a Thermofisher Quattro S ESEM or a ThermoScientific Apreo 2 HV SEM apparatus with a high-stability Schottky field emission gun electron source providing electron resolution of 0.7nm at 30 kV, 1.4 nm at 1 kV. Mechanical testing was performed on an ElectroForce 3200 Mechanical Testing System equipped with a 45N load cell using tension testing methods.Example 2: Synthesis of copolymersSynthesis Bl: Isotactic poly-N-isopropylacrylamide (iPNIPAM)iPr UV light iPrScheme SB1. Synthesis of iPNIPAM.

[0127] Following a literature preparation,1purified ?V-isopropy I acrylamide (NIP AM, 1.6131 g, 14.3 mmol, 143 equiv.) and Y(OTf)3 (1.5833 g, 3.0 mmol, 30 equiv.) were added to a round bottom flask and dried under vacuum for 24 h. Recrystallized AIBN (21 mg, 0.1 mmol, 1 equiv.) was dissolved in MeOH (6.6 mL) and freeze-pump- thawed three times. The AIBN solution was added to the dried reactants. The reaction mixture was cooled to -20 °C and irradiated with three UV lamps (385-400 nm) for 3 d. Following completion of the reaction, the resulting polymer was purified via dialysis (RC tubing, 1 kD MWCO) against H2O five times for 3 h each. The product was dried via lyophilizer to produce the desired polymer, isotactic poly-A-isopropylacrylamide (iPNIPAM), as a white solid (1.5554 g, 96% mass conversion).!H NMR (500 MHz, (CD3)2SO): 5H 7.01-6.75 (m, 1H), 3.86 (s, 1H), 2.00 (s, 1H), 1.57 (s, 1H), 1.38 (s, 1H), 1.05 (s, 6H).Synthesis B2: Atactic poly-N-isopropylacrylamide (aPNIPAM)Scheme SB2. Synthesis of aPNIPAM.

[0128] Following a modified literature preparation,1purified NIP AM (1.5985 g, 14. 1 mmol, 141 equiv.) was added to a round bottom flask and dried under vacuum for 24 h. Recrystallized AIBN (21 mg, 0.1 mmol, 1 equiv.) was dissolved in MeOH (6.6 mL) and freeze-pump-thawed three times. The AIBN solution was added to the dried reactants. The reaction mixture was cooled to -20 °C and irradiated with three UV lamps (385-400 nm) for 3 d. Following completion of the reaction, the resulting polymer was purified via dialysis (RC tubing, 1 kD MWCO) against H2O five times for 3 h each. The product was dried via lyophilizer to produce the desired polymer, atactic poly-A- isopropylaciylamide (aPNIPAM), as a white solid (1.3675 g, 86% mass conversion). 'H NMR (500 MHz, (CD3)2SO): 5H 7.19 (s, 1H), 3.84 (s, 1H), 1.96 (s, 1H), 1.43 (s, 2H), 1.05 (s, 6H).Synthesis B3: Atactic poly-N-tert-butylacrylamide (aPTBAM)Scheme SB3. Synthesis of aPTBAM.

[0129] Following a modified literature preparation,1purified N-tert- butylacrylamide (TBAM, 2.0140 g, 15.8 mmol, 158 equiv.) was added to a round bottom flask and dried under vacuum for 24 h. Recrystallized AIBN (21 mg, 0.1 mmol, 1 equiv.) was dissolved in MeOH (6.6 mL) and freeze-pump-thawed three times. The AIBN solution was added to the dried reactants. The reaction mixture was cooled to -20 °C and irradiated with three UV lamps (385-400 nm) for 3 d. Following completion of the reaction, the resulting polymer was purified via dialysis (RC tubing, 1 kD MWCO) against H2O five times for 3 h each. The product was dried via lyophilizer to produce thedesired polymer, atactic poly-N- / tv / -buly lacrylamide (aPTBAM), as a white solid (1.8422 g, 91% mass conversion). iH NMR (500 MHz, (CD3)2SO): 5H 6.52 (s, 1H), 2.01 (s, 1H), 1.68 (s, 1H), 1.27 (s, 9H).13C NMR (125 MHz, CDCh): 5C 174.89, 51.14, 42.62, 34.86, 28.61.Synthesis B4: Isotactic poly-N-tert-butylacrylamide (iPTBAM)Y(OTf)3Scheme SB4. Synthesis of iPTBAM.

[0130] Following a modified literature preparation,1purified TBAM (2.0752 g, 16.3 mmol, 163 equiv.) and Y(OTf)3(1.7714 g, 3.3 mmol, 33 equiv.) were added to a round bottom flask and dried under vacuum for 24 h. Recrystallized AIBN (21 mg, 0. 1 mmol, 1 equiv.) was dissolved in MeOH (6.6 mL) and freeze-pump-thawed three times. The AIBN solution was added to the dried reactants. The reaction mixture was cooled to -20 °C and irradiated with three UV lamps (385-400 nm) for 3 d. Following completion of the reaction, the resulting polymer was purified via dialysis (RC tubing, 1 kD MWCO) against H2O five times for 3 h each. The product was dried via lyophilizer to produce the desired polymer, isotactic poly-7V-tert-butylacrylamide (iPTBAM), as a white solid (1.6147 g, 78% mass conversion). 'H NMR (500 MHz, (CD3)2SO): 5H 6.66- 6.24 (m, 1H), 2.04 (s, 1H), 1.66 (s, 1H), 1.28 (s, 9H).13C NMR (125 MHz, CDCh): 5C 174.58, 51.17, 42.56, 34.22, 28.75.Synthesis B5: Atactic polyacrylonitrile / poly-N-tert-butylacrylamide copolymer (aPAN- TB)Scheme SB5. Synthesis of aPAN-TB.

[0131] aPTBAM (309.9 mg, 0.002 mmol, 1 equiv.) was added to a round bottomflask and was dissolved in SOCh (360 mL, excess). The reaction mixture was then equipped with a reflux condenser and Dean-Stark trap to collect produced HC1 and heated to 100 °C for 24 h. The resulting solution was quenched by pouring over ice, and the resulting precipitate was collected and washed with H2O and dried to produce the desired product, atactic polyacrylonitrile / poly-AGert-butylacrylamide copolymer (aPAN- TB), as a brown solid (157.3 mg, 89% yield based on an average 70% conversion to PAN). 'H NMR (500 MHz, (CD3)2SO): 5H 7.90 (s, 1H), 3.10 (s, 1H), 2.68-2.58 (m, 1H), 2.11-1.83 (m, 2H), 1.77-1.57 (m, 2H), 1.26 (s, 5H).13C NMR (125 MHz, (CD3)2SO): 5C 171.64, 120.43, 120.12, 119.70, 50.76, 41.67, 34.43, 33,28, 32.76, 28.45, 28.10, 27.51, 26.97.Synthesis B6: Isotactic polyacrylonitrile / poly-N-tert-butylacrylamide copolymer (iPAN- TB)Scheme SB6. Synthesis ofiPAN-TB.

[0132] iPTBAM (294.6 mg, 0.002 mmol, 1 equiv.) was added to a round bottom flask and was dissolved in SOC12(360 mL, excess). The reaction mixture was then equipped with a reflux condenser and Dean-Stark trap to collect produced HC1 and heated to 100 °C for 24 h. The resulting solution was quenched by pouring over ice, and the resulting precipitate was collected and washed with H2O and dried to produce the desired product, isotactic polyacrylonitrile / poly-A-tert-butylacrylamide copolymer (iPAN-TB), as a brown solid (162.6 mg, 92% yield based on an average 70% conversion to PAN). 'H NMR (500 MHz, (CD3)2SO): 8H 7.89 (s, 1H), 3.09 (s, 1H), 2.80 (s, 1H), 2.02 (s, 2H), 1.90-1.60 (m, 2H), 1.23 (s, 5H).13C NMR (125 MHz, (CD3)2SO): 5C 171.82, 120.55, 120.10, 50.64, 41.29, 33.60, 32.74, 28.51, 27.00, 26.69.Gel Permeation Chromatography (GPC)

[0133] GPC data was collected using two Shodex GPC KD-806M columns in sequence in DMF mobile phase (0.025 M LiBr) running at 60 °C at a 1.0 mL*min1flow rate. Molecular weight calculations were performed using the poly- - isopropylacrylamide dn / dc of 0.071 g / mL2and polyacrylonitrile dn / dc of 0.084 g / mL.3Table SI. Data obtained from analytical GPC (DMF column, 0.025 M LiBr, 60 °C) of PTBAM and PNIPAM polymers.Infrared Spectroscopy (IR)

[0134] IR data was collected via an ATR module on an FTIR spectrometer. Solid samples were placed directly onto the sample platform and %Transrmttance was collected. The spectra were analyzed for diagnostic peaks, especially in the nitrile stretch region (-2300-2200 wavenumbers).Differential Scanning Calorimetry (DSC)

[0135] Differential scanning calorimetry (DSC) was performed to determine thermal properties, specifically the glass transition temperature (Tg), of the postconversion polymers. Samples were loaded into a TO aluminum DSC pan and sealed. One heating / cooling cycle of 10-150 °C and 150-10 °C was performed to remove any residual defects prior to data collection. Data was collected via a heating / cooling cycle of 10-300 °C, at a heating rate of 10 °C»min-1.Thermogravimetric Analysis (TGA)

[0136] Thermogravimetric analysis (TGA) was performed to further determine thermal properties, specficially the decomposition temperature (Td), of the postconversion polymers. The samples were loaded into a Platinum 100 pL TGA pan. Tests were run from 10-600 °C, at a heating rate of 10 °C*min-1.Example 3: Fabrication, Processing, and Characterization of Fibers Fiber Fabrication

[0137] Dope solutions for Sigma PAN, aPAN-TB, and iPAN-TB were prepared at 10 wt% and then used to fabricate fibers via wet spinning. The solutions were added to a syringe equipped with tubing and an 18G blunt needle and injected into a 85: 15 EhCTMeOH coagulation bath cooled to 0 °C via a syringe pump at an injection rate of 8 mL h1The resulting precipitate fiber was pulled along the coagulation bath and up to the automated spindles followed by an H2O wash bath. The collected fibers were then dried for 24 h prior to processing.Fiber Processing

[0138] The as-spun Sigma PAN, aPAN-TB, and iPAN-TB fibers were processed in muffle and tube furnaces to create carbon fiber. The first step towards carbon fiber was cyclization via muffle furnace processing. The as-spun fiber samples were placed in an alumina crucible in the muffle furnace chamber. The heating sequence was as follows: 50 min ramp to 250 °C, 1 h hold at 250 °C, and an ambient ramp down to room temperature. The second step was carbonization via tube furnace processing. The post- muffle furnace samples were placed in an alumina crucible and added to the tube of the furnace. The heating sequence was as follows: 15 min vacuum pump, 10 min N2 purge, 150 min ramp to 1500 °C at a rate of 10 °C min-1, 1 h hold at 1500 °C, and an ambient ramp down to room temperature.Mechanical Testing of Fibers

[0139] Mechanical performance data was collected via tensile testing using a 45 N force cell. Due to the physical limitations of the fiber samples, the standard grips could not be used alone. For this reason, the fibers were superglued at each end between two rectangular pieces of standard copy paper to act as a second set of grips for mechanical testing. The distance between the paper grips was measured as the length of the fiber for proceeding calculations. A stress vs. strain plot was created for further analysis using the equations below:Tensile testing was performed only on as-spun and post-muffle furnace fibers, as the posttube furnace fibers were too brittle to be loaded into the instrument for testing.Fiber Fabrication

[0140] Fibers were produced for Sigma PAN, aPAN-TB, and iPAN-TB via a wet spinning protocol. Dope solutions were prepared at 10 wt% in DMF. To prepare these solutions, the solid PAN samples were slowly added into the DMF solution to prevent aggregation and improve dissolution. The solutions were sonicated and stirred for up to a week until the solution was fully homogeneous. It is worth noting that the iPAN-TB solution did not reach full homogeneity over a week, so the resulting solution was in actuality ~4-5 wt%. The samples were then fabricated into fibers via wet spinning. The solutions were added to a syringe equipped with tubing and an 18G blunt needle and injected into a 85: 15 EECFMeOH coagulation bath cooled to 0 °C via a syringe pump at an injection rate of 8 mL*h1The resulting precipitate fiber was manually pulled along the wet spinner spindles using forceps and through an H2O wash bath and inline heater set to 100°C. The collected fibers were then dried for 24 h prior to processing.Fiber Processing

[0141] The as-spun Sigma PAN, aPAN-TB, and iPAN-TB fibers were processed through a muffle and tube furnace to create carbon fiber. The first processing step towards carbon fiber was cyclization via muffle furnace processing. The as-spun fiber samples were placed in an alumina crucible in the muffle furnace chamber. The heating sequence was as follows: 50 min ramp to 250 °C at a rate of 5 °Omin-1, 1 h hold at 250 °C, ambient ramp down to room temperature. The second processing step was carbonization via tube furnace processing. The post-muffle furnace samples were placed in an alumina crucible and added to the tube of the tube furnace. The heating sequence was as follows: 15 min vacuum pump, 10 min N2 purge, 150 min ramp to 1500 °C at a rate of 10 °Omin-1, 1 h hold at 1500 °C, ambient ramp down to room temperature.Scanning Electron Microscopy (SEM) Imaging

[0142] Scanning electron microscopy (SEM) experiments were performed to see the differences in morphology between as-spun, post-muffle furnace, and post-tube furnace fibers of Sigma PAN, aPAN-TB, and iPAN-TB. Images of the Sigma PAN, aPAN-TB, and iPAN-TB post-tube furnace fibers were collected using a Thermofisher Quattro S ESEM. Images of the 1PAN as-spun and post-muffle furnace fibers were collected using a ThermoScientific Apreo 2 HV SEM. All images were collected with an ETD at 65-800x magnification utilizing a potential of 1.00 kV for as-spun and post-muffle furnace fibers and 5.00 kV for post-tube furnace fibers and a spot size of 3-4 to avoid excessive charging of the organic fibers. The average diameter of the imaged fibers was determined via ImageJ using the least magnified image, in which the center of the fiber was located and set as the initial measurement. Four further measurements were taken along the fiber at even intervals. This was repeated three times for each fiber type, and the resulting measurements were averaged. This average diameter was later used in tensile data calculations for the fibers.Table S2. The average diameters of each fiber type, based on five measurement points on three individual fibers.Mechanical Testing of Fibers

[0143] Tensile testing data was collected via tension testing using a 45 N force cell. Due to the physical limitations of the fiber samples, the standard grips could not be used alone. For this reason, the fibers were superglued at each end between two rectangular pieces of standard copy paper to act as a second set of grips for mechanical testing. The distance between the paper grips was measured as the length of the fiber for proceeding calculations. A stress % vs. strain plot was created for further analysis using the equations below:Displacement (mm) - Initial Displacement(mm)Strain% =Sample Length (mm)Tensile testing was performed on as-spun and post-muffle furnace fibers. Post-tube furnace fibers were too brittle to be loaded into the instrument for testing.2) p Maanlavleyrntica Pla.ncoamly / teicna / lle. a Trhne / k Cnhorwolmedagteo-gcreanmter S / einrsieigs:ht Ps / NthIPe-AcMhr.o hmtatptosg: / r / wamw-wse.mriaelsv-ernReferences1) Isobe, Y.; Fujioka, D.; Habaue, S.; Okamoto, Y. J. Am. Chem. Soc., 2001, 123, 7180-7181. pnipam3) Moskowitz, J. D.; Wiggins, J. S. Polym. Degrad. Stab., 2016, 125, 76-86.Example 4: Synthesis of Precision Polyacrylonitrile for Ultra-High-Performance Carbon Fibers

[0144] To develop a method of synthesizing “precision PAN" polymers used to fabricate ultra-high-performance CFs and composites, the following experiments were conducted. Low dispersity (D < 1.3) poly(t-butylacrylamide) (PTBAM) and poly(TBAM-Am) copolymers of moderate to ultra-high-MW (i.e., 0.2 to 3-5 million Da) were synthesized via photoinitiated reversible addition-fragmentation chain-transfer (photo-RAFT) polymerization, followed by an irreversible post-polymerization modification step to convert it to a PAN copolymer. Low dispersity PTBAM and copolymers of varying MWs and with controlled stereochemistry were synthesized using yttrium triflate (>92% meso isotacticity), followed by conversion in post to a PAN copolymer, where the higher isotacticity is expected to afford greater cyclization of nitrile groups, thus yielding more graphitic materials. CFs were fabricated using a labscale wet spinning equipment setup, followed by characterizing the fiber diameter, microstructure, and mechanical properties as a function of MW, dispersity, and degree of isotacticity. These materials were compared to commercial CFs to benchmark performance.

[0145] A photoinduced RAFT polymerization was employed to make low dispersity PTBAM (FIG. 2A) weighing -200 and -1250 kDa. The preliminary infrared (IR) spectroscopy characterization data (FIG. 2B) demonstrated the irreversible chemical conversion of the amide groups to nitriles using excess thionyl chloride (SOCI2), as evidenced by the emergence of the -CN stretching peak at -2240 cm'1(FIG. 2B, inset). Moreover, elemental analysis of the product PAN copolymer revealed a 70- 84% range for conversion to nitrile groups, while 1H NMR analysis (FIG. 2C) corroborated the lower end of this range (-67%). The same chemical transformation can be done onisotactic PTBAM.

[0146] A wet spinning and thermal processing workflow was developed to fabricate pre-fiber PAN filaments, followed by heat curing this precursor to make CFs and testing its elastic moduli (E) and tensile strength. The higher molar mass PAN alone is expected to show greater stiffness and tensile strength in comparison to existing commercial CFs. However, the researchers simultaneously pursue CFs comprising “precision” PAN copolymer with isotactic side-chain groups. There are many sources of commercially available PAN and CF-based composites that can be compared to the CFs and related materials, thus serving as quantifiable benchmarks. The results of these experiments demonstrated a completely different approach to synthesizing low dispersity, high MW, and stereo-defined “precision PAN” that can lead to higher performance CFs. Wider adoption of these methods leads to lower costs and less material needed for the fabrication of higher performance CFs.Example 5: Synthetic Methods to Prepare Precision PAN & Related Precursors

[0147] To demonstrate a method of PTBAM polymerization, the following experiments were conducted. A schematic diagram of the polymerization reaction is provided as FIG. 3. A-tertbutyl acrylamide (TBAM, 446.99 mg, 2,358.67 eq, 3.5144 mmol) was added to a 5 mL round bottom flask and dissolved in 1.92 mL of dimethyl sulfoxide (DMSO). A xanthate iniferter, synthesized according to a reported preparation, was added to the reaction mixture (0.016 mg, 16 pL of a 1 mg / mL stock solution in DMSO, 1 eq). The reaction mixture was then purged with N2 for 60 min. The reaction was then added to a Rayonet photochemical reactor equipped with 254 nm UV bulbs and reacted for 24 h. Following the completion of the reaction, the reaction mixture was precipitated with water. The precipitate was collected, redissolved in dichloromethane (CH2CI2), and precipitated with water four more times to remove any unreacted monomer. The resulting white precipitate was dried, producing the polymer product (220 mg).

[0148] To demonstrate a method of converting the PTBAM polymer described above to a PAN polymer, the following experiments were conducted. A schematic diagram of the conversion reaction is provided as FIG. 4. PTBAM (100 mg, 1 eq) was added to a 100 mL round bottom flask and dissolved in thionyl chloride (SOCI2, 60 mL, excess). The reaction vessel was equipped with a Dean-Stark trap and reflux condenser. The reaction was heated to 100 °C and refluxed for 16 h. Following completion of thereaction, the excess SOCb was quenched by pouring the reaction mixture over ice. The resulting solution was filtered along with any precipitated product in the flask and washed with water several times. Excess SOCb trapped in the polymer was removed by dissolving the product in dimethylformamide (DMF) and removing the organic solvent via a roto-evaporator. The resulting orange solid was dried under vacuum.Example 6: Synthetic Methods to Prepare Ultra-High Molecular Weight Copolymers

[0149] To demonstrate a method of synthesizing ultra-high molecular weight copolymers, the following experiments were conducted.

[0150] To perform a polymerization of 2% AM Poly(AMm-TBAMn) ultra-high molecular weight copolymer (see FIG. 5), acrylamide (AM, 9.5 mg, 1,066 eq) and TBAM (480.9 mg, 52,224 eq) were added to a 5 mL round bottom flask and dissolved in 1.5 mL of DMSO. The xanthate iniferter, synthesized according to a reported preparation, was added to the reaction mixture (0.016 mg, 16 pL of a 1 mg / mL stock solution in DMSO, 1 eq). The reaction mixture was then purged with N2 for 60 min. The reaction was then added to a Rayonet photochemical reactor equipped with 254 nm UV bulbs and reacted for 24 h. Following the completion of the reaction, the reaction mixture was precipitated with water. The precipitate was collected, redissolved in CH2CI2, and precipitated with water four more times to remove any unreacted monomer. The resulting white precipitate was dried, producing the copolymer product (140.7 mg).

[0151] To produce 5%, 10%, and 20% AM Poly(AMm-TBAMn) copolymers, the above procedure was repeated to produce copolymers with varying percentages of poly(AMm-TBAMn) using the following ratios of AM, TBAM, and xanthate:5%: AM (15.0 mg, 2,665 eq), TBAM (463.8 mg, 50,626 eq), and xanthate (0.016 mg, 16 pL of a 1 mg / mL stock solution in DMSO, 1 eq);10%: AM (28.6 mg, 5,329 eq), TBAM (440.2 mg, 47,961 eq), and xanthate (0.016 mg, 16 pL of a 1 mg / mL stock solution in DMSO, 1 eq); and20%: AM (58.8 mg, 10,658 eq), TBAM (390.3 mg, 42,633 eq), and xanthate (0.016 mg, 16 pL of a 1 mg / mL stock solution in DMSO, 1 eq)

[0152] To demonstrate a method of converting the above Poly(AMm-TBAMn) copolymers into ultra-high molecular weight PAN copolymers, the following experiments were conducted. A schematic diagram of the conversion reaction is provided as FIG. 6. A 2% Poly(AMm-TBAMn) copolymer (98.3 mg, 1 eq) was added to a 100 mL round bottom flask and dissolved in SOCh (60 mL, excess). The reaction vessel wasequipped with a Dean-Stark trap and reflux condenser. The reaction was heated to 100 °C and refluxed for 16 h. Following completion of the reaction, the excess SOCb was quenched by pouring the reaction mixture over ice. The resulting solution was filtered along with any precipitated product in the flask and washed with water several times. Excess SOCI2 trapped in the polymer was removed by dissolving the product in DMF and removing the organic solvent via a rotoevaporator. The resulting orange solid was dried under vacuum, producing the product (50.9 mg).Example 7 : Synthetic Methods to Prepare Isotactic PTBAM & PAN Polymers

[0153] To prepare isotactic PTBAM & PAN polymers, the following experiments were conducted. A schematic diagram of the reaction is provided at FIG. 2A. TBAM (607.4 mg, 2664 eq) and yttrium triflate (536.3 mg, 0.5 M) were added to a 50 mL jacketed round bottom flask and dissolved in 0.78 mL of DMSO and 1.23 mL of MeOH. The xanthate iniferter, synthesized according to a reported preparation,1was added to the reaction mixture (0.45 mg, 0.45 mL of a 1 mg / mL stock solution in DMSO, 1 eq). The reaction mixture was then purged with N2 for one hour. The reaction was then added to a Rayonet RPR-100 photochemical reactor equipped with sixteen 254 nm UV bulbs and reacted for 72 hours while being cooled by flowing ice water through the jacketed flask. Following the completion of the reaction, the reaction mixture was precipitated with water. The precipitate was collected, redissolved in CH2CI2, and precipitated with water four more times to remove any unreacted monomer. The resulting white precipitate, consisting of PTBAM polymers with a molecular weight of about 300 kD was dried, producing the copolymer product.

[0154] The conversion reaction described above was repeated without the addition of yttrium triflate (Y (OTf)s ) to form atactic medium molecular weight PTBAM polymers.

[0155] The atactic and isotactic PTBAM polymers were subjected to13C NMR spectral analysis. The resulting13C NMR spectra are shown in FIG. 7 for the atactic (top) and isotactic (bottom) PTBAM polymers.

[0156] In additional experiments, the reaction will be cooled to 0-4 °C and the photoreactor may conduct the photochemical reaction at a wavelength of 365 nm that is more strongly absorbed by the xanthate iniferter.Example 8: Synthetic Methods to Prepare Stereo-based Atactic-Isotactic PAN Block Copolymers

[0157] To prepare poly((atac)TBAMm-(iso)TBAMn) block copolymers containing a mixture of atactic and isotactic TBAM polymer blocks, the following experiments were conducted. A schematic diagram of the reaction is provided at FIG. 8. Polymerization will be used to generate atactic PTBAM as described above (Step 1), followed by adding in the Lewis acid catalyst, yttrium triflate (Y(OTf)3), and lowering the temperature via the jacketed round bottom flask and adding more TBAM monomer in a second step in the same flask (Step 2). This sequence of reactions will create an atactic PTAB block followed by an isotactic PT AB block, which can be converted to the stereo PAN block copolymer after conversion via SOCh (Step 3) or other dehydration reaction conditions described herein.Example 9: Synthetic Methods to Prepare Atactic Ultra-High Molecular Weight PAN Copolymer

[0158] To prepare atactic medium molecular weight PAN copolymers, the following experiments were conducted. A schematic diagram of the reaction is provided at FIG. 5. Acrylamide (8.1 mg, 53 eq) and TBAM (491.4 mg, 2611 eq) were added to a 5 mL round bottom flask and dissolved in 1.5 mL of DMSO. The xanthate iniferter, synthesized according to a reported preparation,1was added to the reaction mixture (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq). The reaction mixture was then purged with N2 for one hour. The reaction was then added to a Rayonet RPR- 100 photochemical reactor equipped with sixteen 254 nm UV bulbs and reacted for 72 hours. Following the completion of the reaction, the reaction mixture was precipitated with water. The precipitate was collected, redissolved in CH2CI2, and precipitated with water four more times to remove any unreacted monomer. The resulting white precipitate was dried, producing the copolymer product (107.5 mg).5%, 10%, and 20%AMPoly(AMm-TBAMri) copol mers'.

[0159] The above procedure was repeated to produce copolymers with varying percentages of poly(AMm-TBAMn) using the following ratios of AM, TBAM, and xanthate:5%: AM (14.3 mg, 133 eq), TBAM (478.3 mg, 2531 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)10%: AM (29.8 mg, 266 eq), TBAM (454.8 mg, 2398 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)20%: AM (56.2 mg, 533 eq), TBAM (403.4 mg, 2132 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)Example 10: Synthetic Methods to Prepare Atactic Medium and High Molecular Weight PAN Copolymers via Direct Polymerization of TBAM with Acrylonitrile (AN)

[0160] To synthesize 33%, 50%, and 66% AN poly(ANm-TBAMn) medium and high molecular weight copolymers (-300-1000 kDa), the following experiments were conducted. A schematic diagram of the synthesis reactions is provided at FIG. 9. The procedure illustrated in FIG. 9 will be used to produce poly(ANm-TBAMn) copolymers with varying percentages of acrylonitrile (AN) using the ratios of AN, TBAM, and xanthate shown below. Without being limited to any particular theory, it is thought that higher molecular weight PAN copolymers can be synthesized more readily by incorporating the more soluble TBAM monomer into a direct PAN polymerization, followed by converting as many of the TBAM monomer subunits as possible to nitrile groups.66%: AN (371.6 mg, 1961 eq), TBAM (77.48 mg, 980 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)50%: AN (131.86 mg, 1667 eq), TBAM (315.9 mg, 1667 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)33%: AN (155.03 mg, 980 eq), TBAM (185.81 mg, 1667 eq), and xanthate (0.33 mg, 0.33 mL of a 1 mg / mL stock solution in DMSO, 1 eq)Example 11 : Alternative Methods to Convert PTBAM Polymers and Copolymers to PAN Polymers and Copolymers

[0161] To validate alternative methods for converting the precursor PTBAM polymers and copolymers into PAM polymers and copolymers as described herein, the following experiments were conducted. Various dehydration reactions to convert the amide moieties of the PTBAM to nitrile moieties were tested as described below. SOCh conversion with xylene:

[0162] To improve solubility post-reaction, a 10% Poly(AMm-TBAMn) ultra high molecular weight copolymer (101.7 mg, 1 eq) was added to a 250 mL round bottom flask and dissolved in SOCL (60 mL, excess) and 60 mL xylene. The reaction vessel was equipped with a dean stark trap and reflux condenser. The reaction was heated to 100 °Cand refluxed for 16 hours. Following completion of the reaction, the excess SOCb was quenched by pouring the reaction mixture over ice. The resulting solution was filtered along with any precipitated product in the flask and washed with water several times. Excess SOCh trapped in the polymer was removed by dissolving the product in DMF and removing the organic solvent via a rotoevaporator. The resulting orange solid was dried under vacuum, producing the product.TFAA conversion:

[0163] A PAM polymer (56.3 mg, 1 eq) was dissolved in 7 mL of anhydrous CH2CI2 and the mixture was cooled in a dry ice / isopropanol bath. Triethylamine (0.29 mL, 75,972 eq) was added to the reaction, followed by the dropwise addition of TFAA (0.20 mL, 50,648 eq). The reaction mixture was slowly warmed to room temperature and stirred for 16 hours. Following the reaction, the organic solvent was removed via a rotoevaporator.AICI3 conversion:

[0164] AlCh (0.5268 g, 200 eq) and KI (1.1317 g, 600 eq) were added to a mixture of 0.1 mL MeCN and 1. 1 mL water, and the reaction mixture was stirred for 30 minutes at room temperature. A PAM polymer (78.0 mg, 1 eq) was added to the reaction mixture. The reaction was then refluxed at 80 °C for 16 hours. Following the reaction, the solvent was removed via a rotoevaporator.ZnCh conversion:

[0165] A PAM polymer (53.8 mg, 1 eq) and ZnCL (96.3 mg, 25,324 eq) were added to a mixture of 2.5 mL MeCN and 2.5 mL water. The reaction mixture was then microwaved in a watt micro wave at half power for 60 seconds. Following the reaction, the mixture was extracted with CH2CI2, and the organic layer was dried over sodium sulfate and evaporated via a rotoevaporator.PBrs conversion:

[0166] A PTBAM polymer (100 mg, 1 eq) was dissolved in 40 mL of anhydrous dichloroethane, and the mixture was stirred at 70°C overnight, after which time, it was diluted with CH2CI2. The mixture was washed with NaOH in water, and dried with sodium sulfate, and the solvent was removed via a rotoevaporator. The crude mixture was purified by flash chromatography silica column (0-50% EtOAc / hexane, 40 g column) to provide the product. This synthesis was adjusted from a similar reported synthetic preparation.rCOCl conversion:

[0167] A pTBAM polymer (504.9 mg, 1 eq) and triphenylphosphine oxide (11.04 mg, 0.01 eq) were dissolved in 16 mL of dry MeCN in a 50-mL round botom flask with a stir bar, followed by the addition of triethylamine (1.205 g, 3 eq). The resulting solution was treated dropwise with neat oxalyl chloride (COCH) using an adjustable volume pipete (0. 1-1.0 mL) and the mixture was stirred for 10 minutes. The crude mixture obtained was purified by flash chromatography silica column (petroleum ether / EtOAc - 9 / 1). This synthesis was adjusted from a similar reported synthetic preparation.

[0168] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional steps or components. The singular forms “a,” “and,” “the” and “said” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of’ and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0169] In view of the above, it will be seen that the several objects are achieved and other advantageous results atained.

[0170] As various changes could be made in the above compositions and processes without departing from the scope of the embodiments, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Claims

CLAIMS:

1. A copolymer comprising a repeat unit having a structure of Formula 1 and F ormula2:whereinRi is hydrogen or alkyl;R2 is alkyl; and m+n is an integer of from about 500 to about 80000; wherein the copolymer has at least 50 percent of nitrile pendant groups are isotactic (meso-meso triad) and has a weight average molecular weight (Mw) of from about 20 kilodaltons (kDa) to about 5000 kDa.

2. The copolymer of claim 1, wherein Ri is hydrogen or Ci to Cv alkyl.

3. The copolymer of claim 1, wherein Ri is hydrogen or Ci to C3 alkyl.

4. The copolymer of claim 1, wherein Ri is hydrogen.

5. The copolymer of any one of claims 1 to 4, wherein R2 is Ci to G alkyl.

6. The copolymer of any one of claims 1 to 4, wherein R2 is branched C3 to alkyl.

7. The copolymer of any one of claims 1 to 4, wherein R2 is iso-propyl, iso-butyl, isopentyl, sec -butyl, sec-pentyl, tert-butyl, or tert-pentyl.

8. The copolymer of any one of claims 1 to 4, wherein R2 is iso-propyl or tert-butyl.

9. The copolymer of any one of claims 1 to 4, wherein R2 is tert-butyl.

10. The copolymer of any one of claims 1 to 9, wherein the weight average molecular weight is from about 100 kDa to about 5000 kDa.

11. The copolymer of any one of claims 1 to 9, wherein the weight average molecular weight is from about 200 kDa to about 4000 kDa.

12. The copolymer of any one of claims 1 to 9, wherein the weight average molecular weight is from about 250 kDa to about 3000 kDa.

13. The copolymer of any one of claims 1 to 12, wherein the copolymer has at least 50 percent of nitrile pendant groups are isotactic (meso-meso triad).

14. The copolymer of any one of claims 1 to 12, wherein the copolymer has at least 60 percent of nitrile pendant groups are isotactic (meso-meso triad).

15. The copolymer of any one of claims 1 to 12, wherein the copolymer has at least 70 percent of nitrile pendant groups are isotactic (meso-meso triad).

16. A carbon fiber derived from the copolymer of any one of claims 1 to 15.

17. A carbon fiber composite comprising fibers derived from the copolymer of any one of claims 1 to 15 or carbon fibers of claim 16.

18. A method of preparing a copolymer comprising: forming a reaction mixture of an alkyl acrylamide, rare earth metal tnfluoromethanesulfonates (rare earth metal triflates), and a polymerization initiator; exposing the reaction mixture to ultraviolet (UV) light to form a poly(alkyl acrylamide): and dehydrating poly(alkyl acrylamide) to form a copolymer comprising nitrile and alkyl amide pendant groups.

19. The method of claim 18, wherein the polymerization initiator is a free radical polymerization initiator, a controlled radical polymerization initiator, a cationic polymerization initiator, or an anionic polymerization initiator.

20. The method of claim 18 or 19, wherein the alkyl acrylamide is methyl acrylamide, ethyl acrylamide, n-propyl acrylamide, iso-propyl acrylamide, n-butyl acrylamide, isobutyl acrylamide, sec-butyl acrylamide, or tert-butyl acrylamide.

21. The method of claim 20, wherein the alkyl acrylamide is iso-propyl acrylamide or tert-butyl acrylamide.

22. The method of claim 20, wherein the alkyl acrylamide is tert-butyl acrylamide.

23. The method of any one of claims 18 to 22, wherein the rare earth triflate comprises yttrium triflate, scandium triflate, lanthanum triflate, cerium triflate, praseodymium inflate, neodymium triflate, samanum triflate, europium triflate, gadolinium triflate, terbium triflate, holmium triflate, erbium triflate, thulium triflate, ytterbium triflate, lutetium triflate, or a combination thereof.

24. The method of any one of claims 18 to 22, wherein the rare earth triflate comprises yttrium triflate.

25. The method of any one of claims 18 to 24, wherein the poly(alkyl acrylamide) is contacted with thionyl chloride (SOCb), phosphorus oxychloride (POCh), or phosphorus pentoxide (P2O5) to dehydrate poly(alkyl acrylamide) to form a copolymer comprising nitrile and alkyl amide pendant groups.

26. The method of claim 25, wherein the poly(alkyl acrylamide) is contacted with thionyl chloride (SOCI2).

27. The method of any one of claims 18 to 26, wherein the reaction mixture is exposed to ultraviolet (UV) light or visible light.

28. The method of any one of claims 18 to 27, wherein the reaction mixture is exposed to ultraviolet (UV) light at a temperature of less than or equal to 0°C.

29. The method of claim 28, wherein reaction mixture is exposed to ultraviolet (UV) light at a temperature of less than or equal to -20°C.

30. The method of any one of claims 18 to 29, wherein the poly(alkyl acrylamide) is dehydrated at a temperature of from about 80°C to about 170°C.

31. The method of any one of claims 18 to 29, wherein the poly(alkyl acrylamide) is dehydrated at a temperature of from about 80°C to about 130°C.

32. The method of any one of claims 18 to 31, wherein dehydrating poly(alkyl acrylamide) results in at least 80%, at least 90%, or at least 100% conversion of the alkyl amide groups to nitrile groups.

33. A copolymer of any one of claims 1 to 15 prepared by the method of any one of claims 18 to 32.

34. A copolymer comprising one or more blocks of repeat units having a structure ofFormula 1, one or more blocks of repeat units having the structure of Formula 1A, and optionally, one or more blocks of repeat units having the structure of Formula 2:Ri is hydrogen or alkyl;R.2 is alkyl; and n+n1is an integer of from about 500 to about 80000; wherein the one or more blocks of repeat units of Formula 1 comprise nitrile pendant groups that are atactic and the one or more blocks of repeat units of Formula 1Acomprise nitrile pendant groups that are isotactic (meso-meso triad); and the one or more optional blocks of repeat units of Formula 2 are either atactic or isotactic (meso-meso triad) and has a weight average molecular weight (Mw) of from about 20 kilodaltons (kDa) to about 5000 kDa.

35. A copolymer comprising one or more blocks of repeat units having a structure of Formula 1, one or more blocks of repeat units having the structure of Formula 1A:wherein n+n1is an integer of from about 500 to about 80000; wherein the block of repeat units of Formula 1 comprise nitrile pendant groups that are atactic and the block of repeat units of Formula 1A comprise nitrile pendant groups that are isotactic (meso-meso triad) and has a weight average molecular weight (Mw) of from about 20 kilodaltons (kDa) to about 5000 kDa.

36. A method of synthesizing a precision polyacrylonitrile (PAN) composition, the method comprising: polymerizing A-tertbutyl acrylamide (TBAM) to form poly N-tertbvtyl acrylamide (PTBAM) using a photothermal polymerization reaction; and forming the polyacrylonitrile (PAN) composition by contacting the PTBAM with excess thionyl chloride (SOCb) to convert the amide moieties of the PTBAM to nitrile moieties.

37. The method of claim 36, wherein the photothermal reaction comprises mixing the TBAM with a xanthate iniferter and illuminating the mixture with UV light at a wavelength of 254 nm.

38. The method of claim 37, further comprising polymerizing N-tertbutyl acrylamide (TBAM) in a mixture with a Lewis acid catalyst to form isotactic poly V-zertbutyl acrylamide (PTBAM).

39. The method of claim 38, wherein the Lewis acid catalyst comprises yttrium tnflate.

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