High temperature oxidative resistance of polyacrylonitrile-methylmethacrylate copolymer powder converting to a carbonized monolith

The doping of polyacrylonitrile (PAN) prior to carbonization can alter the physicochemical nature of the polymer under thermal treatment. The inclusion of a "lower" thermally stable monomer methyl methacrylate (MMA) enables fusion of PAN particles into monoliths and, depending on the heating rate, can control the expansion of the structure and establish pore formation through the volatilization and escape of its thermal degradation products. Moreover, geometry is maintained through the carbonization step, when heated up to 850 degrees C. The exothermic regime of PAN-co-MMA is much broader and the cyclization reaction starts at a lower temperature compared with that of the PAN homopolymer. TGA reveals that the thermal stability of the copolymer, compared with pure PAN at 800 degrees C, has increased by 30 wt.% in air, which is far higher than reported in previous studies of copolymers of PAN. The results show promise in providing a facile mechanism for the production of monolithic PAN-based carbons with the potential of controlled porosity. (C) 2011 Elsevier Ltd. All rights reserved.