Thickness dependence of structural relaxation in spin-cast polynorbornene films with high glass transition temperatures (>613 K)

Elizabeth A. Lewis, Bryan D. Vogt

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The isothermal structural relaxation (densification) of a family of glassy polynorbornene films with high glass transition temperatures (Tg > 613 K) is assessed via spectroscopic ellipsometry. Three polymers were examined: poly(butylnorbornene) (BuNB), poly(hydroxyhexafluoroisopropyl norbornene) (HFANB), and their random copolymer, BuNB-r-HFANB. The effective aging rate, β(T), of thick (∼1.2 μm) spun cast films of BuNB-r-HFANB is approximately 10−3 over a wide temperature window (0.49 < T/Tg < 0.68). At higher temperatures, these polymers undergo reactions that more dramatically decrease the film thickness, which prohibits erasing the process history by annealing above Tg. The aging rate for thick BuNB-r-HFANB films is independent of the casting solvent, which infers that rapid aging is not associated with residual solvent. β (at 373 K) decreases for films thinner than ∼500 nm. However, the isothermal structural relaxation of thin films of BuNB-r-HFANB exhibits nonmonotonic temporal evolution in thickness for films thinner than 115 nm film. The thickness after 18 h of aging at 373 K can be greater than the initial thickness. The rapid aging of these polynorbornene films is attributed to the unusual rapid local dynamics of this class of polymers and demonstrates the potential for unexpected structural relaxations in membranes and thin films of high-Tg polymers that could impact their performance.

Original languageEnglish (US)
Pages (from-to)53-61
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume56
Issue number1
DOIs
StatePublished - Jan 1 2018

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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