Synthesis of polystyrene-block-poly(styrene-co-acrylonitrile) block copolymers and thermoanalytical studies of nitroxide-terminated poly(styrene-co-acrylonitrile) copolymers

The synthesis of polystyrene-block-poly(styrene-co-acrylonitrile) block cop olymers by conversion of polystyrene terminated with 2,2,6,6-tetramethylpip eridine-N-oxyl (TEMPO) are described. We have found a considerable accelera tion in polymerization rate and increasing of molecular weights due to the donor acceptor interaction of styrene and acrylonitrile. Analysis of the bl ock copolymer composition by means of H-1 NMR spectroscopy allowed to deter mine the copolymerization parameters. The comparison with the parameters of the free radical copolymerization shows that there is no influence of TEMP O on the composition. The polydispersity index of the copolymer subchain in the block copolymers decreases rapidly with increasing time of polymerizat ion, depending on the polymerization rate of the copolymerization. The ther mal stability of nitroxide-terminated poly(styrene-co-acrylonitrile) copoly mers was investigated by means of thermogravimetry and pyrolysis gas chroma tography coupled with mass spectrometry. At temperatures above 200 degrees C the splitting of the nitroxyl polymer bond takes place, indicating a weak degradation of the polymer. However, there is no effect of the terminator on the decomposition pattern of the copolymer at 500 degrees C.