Controlling thermomechanical behavior of semicrystalline hydrogenated polynorbornene through the cis- to trans-cyclopentylene ratio

Jared P. Klein, Zachary M. Gdowski, Richard A. Register

Research output: Contribution to journalArticlepeer-review

Abstract

Though polynorbornene synthesized by ring-opening metathesis polymerization has an intrinsically all-cis configuration of the cyclopentylene backbone rings, a fraction of these rings can be epimerized to the trans configuration during hydrogenation over suitable catalysts. By varying the method of hydrogenation, semicrystalline hydrogenated polynorbornenes (hPNs) with trans levels between 0 and 36% were obtained. With increasing trans content, the glass transition temperature, melting point, and enthalpy of melting decrease modestly. By contrast, the temperature at which the hPN crystal transitions into a rotationally disordered polymorph varies strongly with trans content, ranging from 126 °C (all-cis) to 71 °C at 27% trans; at trans contents of 34% and above, no rotationally-ordered phase is observed at any temperature. The room-temperature Young's modulus shows no dependence on trans content, while the yield stress drops by 20% at 1% trans content and slowly decreases further with additional epimerization. The temperature dependence of the Young's modulus differs for trans-containing versus all-cis polymers, while the temperature dependence of the yield stress is set by the polymorph type (rotationally ordered vs. disordered).

Original languageEnglish (US)
JournalJournal of Polymer Science
DOIs
StateAccepted/In press - 2021

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Polymers and Plastics

Keywords

  • epimerization
  • hydrogenated polynorbornene
  • modulus
  • semicrystalline polymers
  • thermomechanical properties
  • yield stress

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