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.