Enhanced glass transition temperature of low molecular weight poly(methyl methacrylate) by initiator fragments located at chain ends

Lanhe Zhang, John M. Torkelson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We discovered important effects of chemically distinct initiator fragments incorporated at chain ends on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA). Polymers of various molecular weight (MW) were synthesized via free radical polymerization (FRP) using 2,2’-azobis(2-methylpropionitrile) (AIBN) and benzoyl peroxide (BPO) as initiator. All samples have identical triad distribution with ∼58% syndiotactic content. The Tg values of ∼3 kg/mol PMMA possessing AIBN and BPO initiator fragments are 11–13 K higher than that of an anionic PMMA standard of similar MW. The elevated Tg values in low MW PMMA synthesized by FRP are attributed to attractive interactions arising from polar chain ends. The Tg-MW dependence becomes weaker at the lowest MWs examined in PMMA samples synthesized by FRP (with AIBN or BPO as initiator) and by anionic polymerization. The methodology of incorporating polar chain ends to increase the Tg of low MW polymers provides new avenues for material design.

Original languageEnglish (US)
Pages (from-to)194-199
Number of pages6
JournalPolymer
Volume122
DOIs
StatePublished - Jul 28 2017

Keywords

  • Chain end
  • Glass transition temperature
  • Methacrylate-based polymer

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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