Abstract: Pauci-chain microspheres prepared by microemulsion polymerization contain only one or at most a few macromolecular chains whose special conformation is much different with that of ordinary polymer, which leads to some interesting physical properties. This paper reports apparent differences in thermal behavior between micro-PS (pauci-chainpolystyrene) and o-PS (ordinary polystyrene) during the DSC scan. Micro-PS displayed two exothermic peaks near 107℃ and 157℃ during the first scan. In the subsequent scan, both of them disappeared and only one glass transition similar to o-PS was shown.With the results from experiments of polarizing microscopy and X-ray diffraction, it can be concluded that both of the exothermic peaks were crystalline peaks.

Key words: Microemulsion polymerization, Pauci-chain polystyrene microsphere, Crystalline peak