Segmental dynamics and dielectric constant of polysiloxane polar copolymers as plasticizers for polymer electrolytes

U. Hyeok Choi, Siwei Liang, Quan Chen, James Runt, Ralph H. Colby

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Dielectric relaxation spectroscopy was used to investigate the segmental dynamics of a series of siloxane-based polar copolymers combining pendant cyclic carbonates and short poly(ethylene oxide) (PEO) chains. The homopolymer with cyclic carbonate as the only side chain exhibits higher glass transition temperature Tg and dielectric constant μs than the one with only PEO side chains. For their copolymers the observed Tg (agreeing well with the predicted values from the Fox equation) and μs decrease with increasing PEO side chain content. These polar polymers exhibit a glassy β relaxation with Arrhenius character, attributed to local chain motions of side groups attached to the main chain, and a segmental α relaxation, associated with the glass transition with a Vogel temperature dependence. As PEO side chain content increases, narrowing of the local glassy β relaxation was observed in the copolymers. The segmental α dynamics were observed to be faster, with an increase in breadth and decrease in strength with increasing PEO side chain content. Owing to the trade-off between Tg and μs, copolymers of intermediate composition result in the highest ionic conductivity when these copolymers are used to plasticize Li single-ion conducting ionomers.

Original languageEnglish (US)
Pages (from-to)3215-3225
Number of pages11
JournalACS Applied Materials and Interfaces
Volume8
Issue number5
DOIs
StatePublished - Feb 10 2016

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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