Thickness dependent thermal rearrangement of an ortho-functional polyimide

Huan Wang, Tai-Shung Chung, D. R. Paul*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The effect of film thickness on the thermal rearrangement of an ortho-functional polyimide, derived from 2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3'-dihydroxy-4,4'-diamino-biphenyl (HAB), to a polybenzoxazole structure was explored over the range from 50. nm to 100. μm. The rate of thermal rearrangement of this ortho-functional polyimide was found to be strongly dependent on film thickness. A thin film of 56. nm experienced a much more rapid and extensive thermal rearrangement process than a thick film of 100. μm as tracked by thermogravimetric analysis, TGA. The conversion of the ortho-functional polyimide to polybenzoxazole commences at a lower temperature for thinner films than for thicker films. Isothermal TGA experiments at 370. °C showed a much larger weight loss, or extent of rearrangement, at a given time for thin films compared to thick films. These observations are believed to reflect greater chain segmental mobility in the thin films, due to the proximity of the free surfaces, and perhaps the reduced diffusional resistance for removal of the evolving volatile compounds accompanying the rearrangement reaction.

Original languageEnglish (US)
Pages (from-to)308-312
Number of pages5
JournalJournal of Membrane Science
Volume450
DOIs
StatePublished - Jan 15 2014

Keywords

  • Diffusional resistance
  • Polymer segmental mobility
  • Thermal rearrangement
  • Thickness dependence

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Science(all)
  • Biochemistry
  • Filtration and Separation

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