Crystallization of low molecular weight atactic polystyrene

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

4 Scopus Citations
View graph of relations

Author(s)

  • Yu Cha
  • Adam N. Raegen
  • Shipei Zhu
  • James A. Forrest

Detail(s)

Original languageEnglish
Pages (from-to)6883-6891
Journal / PublicationSoft Matter
Volume14
Issue number33
Publication statusPublished - 7 Sep 2018
Externally publishedYes

Abstract

We observe and characterize the crystallization of atactic polystyrenes (PS) of nearly oligomeric Mw using atomic force microscopy. We find that the low Mw polystyrene exhibits observable crystals on the surface. The crystals appear to be a few nm thick and nm to microns wide. These crystals grow at all temperatures less than ∼290 K. Melting of crystals was probed over an extended temperature range, and some fraction of the crystals start to melt at 302 K, but some fraction persist to higher temperatures and do not exhibit complete melting until 343 K. The tacticity of the molecules is tested with NMR spectroscopy and found to be atactic. We suggest that the crystals form due simply to the distribution of isomerism along the molecule which necessarily leaves some fraction of the molecules with uniform stereoregularity. This natural crystallinity may be related to previously observed and not definitively explained gel formation in atactic PS (a-PS), as well as cluster formation. The measurements are compared with the theory by Semenov (Macromolecules, 2009, 42, 6761) and together suggest that such crystallinity is possible over a wide range of polymerization index (N), and is limited only by the vanishingly small volume fractions and sluggish growth.

Citation Format(s)

Crystallization of low molecular weight atactic polystyrene. / Cha, Yu; Raegen, Adam N.; Zhu, Shipei; Forrest, James A.

In: Soft Matter, Vol. 14, No. 33, 07.09.2018, p. 6883-6891.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review