Endo/Exo Reactivity Ratios in Living Vinyl Addition Polymerization of Substituted Norbornenes

Steven D. Tsai, Richard A. Register

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Substituted norbornenes may be enchained by vinyl addition polymerization (VAP), through the norbornene double bond. Such monomers are generally prepared by Diels–Alder cycloaddition of cyclopentadiene and the corresponding olefin, which leads to a mixture of endo and exo stereoisomers with potentially very different reactivity, but these differences have not previously been quantified (e.g., as copolymerization reactivity ratios rendo and rexo). A living Pd-based VAP initiator is employed and the consumption of endo and exo monomers to high conversions is measured to determine rendo and rexo; since the polymerization is living, the products are gradient copolymers. For norbornenes bearing n-butyl, norbornyl, or methylhexafluoroisopropanol substituents, rexo = 1–4, and rexo rendo = 0.2–0.8, indicating only moderate deviations from ideal copolymerization behavior. By contrast, for norbornene bearing a pentamethyldisiloxane substituent, rendo is indistinguishable from zero, indicating that the endo isomer is effectively incapable of homopropagation. However, since the polymerization is living, propagation resumes (and chain extension proceeds) when additional exo monomer is charged.

Original languageEnglish (US)
Article number1800059
JournalMacromolecular Chemistry and Physics
Volume219
Issue number11
DOIs
StatePublished - Jun 2018

All Science Journal Classification (ASJC) codes

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

Keywords

  • addition polymerization
  • copolymerization
  • kinetics (polym.)
  • living polymerization
  • metal–organic catalysts/organometallic catalysts

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