Novel characteristics of polystyrene microspheres prepared by microemulsion polymerization

Weihua Ming, Jun Zhao, Xuliang Lu, Changchun Wang, Shoukuan Fu

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

Two kinds of styrene microemulsion systems were polymerized to prepare polystyrene microspheres (micro-PS), one emulsified by sodium dodecyl sulfate (SDS) and coemulsified by 1-pentanol and the other emulsified by octylphenoxypoly(ethoxyethanol) (OP-10). Micro-PS possessed an essentially atactic configuration from 1H-NMR measurement. Comparison of IR spectra showed some conformational differences between micro-PS and ordinary atactic PS (o-PS). Each polystyrene microsphere contains only about three macromolecular chains (so-called pauci-chain microspheres), which adopt a special conformation: individual chains are highly compact, while the whole structure of the microsphere is relatively loose in comparison with a random-coil chain in a multichain system. There were apparent differences in thermal behaviors between micro-PS and o-PS during the DSC scan. Micro-PS displayed two exotherms near 107 and 157 °C during the first scan. In the subsequent scan, both exotherms disappeared and only one glass transition similar to o-PS was shown. The first exotherm might be due to the sintering of polystyrene microspheres with small particle sizes. From wide-angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) studies, the second exotherm could be ascribed to the relatively compact conformation of polystyrene chains and the consequently formed slightly ordered regions inside micro-PS during the heating process. The special conformation was the driving force leading to its novel thermal behaviors. This is perhaps the first report that polystyrene from direct free radical polymerization has the ability to form some kind of ordered structure.

Original languageEnglish
Pages (from-to)7678-7682
Number of pages5
JournalMacromolecules
Volume29
Issue number24
DOIs
StatePublished - Jan 1 1996

Scopus Subject Areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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