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

The conformation change of pauci-chain polystyrene microsphere (micro-PS) upon heating was investigated by in-situ FTIR. For the peaks at 1492 and 1452 cm-1 due to phenyl ring semicircle stretch, there are two discontinuities in the plots of peak height versus temperature. The first discontinuity at around 100 °C corresponds to the glass transition. The second discontinuity at about 155 °C is in good agreement with the second exotherm 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.