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

Lanhe Zhang; John M. Torkelson

doi:10.1016/j.polymer.2017.06.054

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

Chemical and Biological Engineering

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

We discovered important effects of chemically distinct initiator fragments incorporated at chain ends on the glass transition temperature (T_g) 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 T_g 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 T_g values in low MW PMMA synthesized by FRP are attributed to attractive interactions arising from polar chain ends. The T_g-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 T_g 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	https://doi.org/10.1016/j.polymer.2017.06.054
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

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

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{\textquoteright}-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.",

keywords = "Chain end, Glass transition temperature, Methacrylate-based polymer",

author = "Lanhe Zhang and Torkelson, {John M.}",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier Ltd",

year = "2017",

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doi = "10.1016/j.polymer.2017.06.054",

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journal = "Polymer",

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T1 - Enhanced glass transition temperature of low molecular weight poly(methyl methacrylate) by initiator fragments located at chain ends

AU - Zhang, Lanhe

AU - Torkelson, John M.

PY - 2017/7/28

Y1 - 2017/7/28

N2 - 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.

AB - 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.

KW - Chain end

KW - Glass transition temperature

KW - Methacrylate-based polymer

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

Abstract

Funding

Keywords

ASJC Scopus subject areas

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