Chain conformation change upon heating for pauci-chain polystyrene microsphere made by microemulsion polymerization

The conformation change of pauci-chain polystyrene microsphere (micro-PS) u pon hearing was investigated by in-situ FTIR. For the peaks at 1492 and 145 2 cm(-1) due to phenyl ring semicircle stretch, there are two discontinuiti es in the plots of peak height versus temperature. The first discontinuity at around 100 degrees C corresponds to the glass transition. The second dis continuity at about 155 degrees C is in good agreement with the second exot herm in the first DSC scan, which clearly suggests a non-negligible change of the chain conformation at this temperature. This finding may be of help in further illustrating the two exotherms of micro-PS in its first DSC scan .