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 language | English (US) |
---|---|
Pages (from-to) | 194-199 |
Number of pages | 6 |
Journal | Polymer |
Volume | 122 |
DOIs | |
State | Published - Jul 28 2017 |
Funding
This work was supported by the University Partnership Initiative between Northwestern University and The Dow Chemical Company, a McCormick School of Engineering Terminal Year Fellowship (L.Z.), and a Weertman Fellowship (L.Z.).
Keywords
- Chain end
- Glass transition temperature
- Methacrylate-based polymer
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry