Carbon Fibers Prepared from Tailored Reversible-Addition-Fragmentation Transfer Copolymerization-Derived Poly( acrylonitrile)-coPoly( methylmethacrylate)

Reversible-addition fragmentation-transfer (RAFT) polymerization of acrylonitrile (AN) was performed with 2-(2-cyano-2-propyl-dodecyl)trithiocarbonate as RAFT agent and azobis(isobutyronitrile) as initiator. Linear polyacrylonitrile (M-n=133,000 g/mol, PDI=1.34) was prepared within 7 h in 86% isolated yield. High-yield copolymerization with methyl methacrylate (MMA) was performed and copolymerization parameters were determined according to Kelen and Tudos at 90 degrees C in ethylene carbonate yielding r(AN)=0.2 and r(MMA)=0.42. The molecular weights, polydispersity indices (PDIs), and MMA content of the copolymer were adjusted in a way that precursor fibers could be prepared via wet spinning. These precursor fibers had round cross-sections and a dense morphology, showing tenacities of 40-50 cN/tex and elastic moduli of 900-1000 cN/tex at a fineness of 1 dtex and an elongation of 13-17%. Precursor fibers were oxidatively stabilized and then carbonized at different temperatures. A maximum tensile strength of 2.5 GPa was reached at 1350 degrees C. Thermal analysis, infrared and Raman spectroscopy, wide-angle X-ray scattering, scanning electron microscopy, and tensile testing were used to characterize the resulting carbon fibers. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1322-1333