Molecular mechanisms for the optical activities of polyisocyanates induced by intramolecular chiral perturbations

Hong Gu, Takahiro Sato, Akio Teramoto, Lionel Varichon, Mark M. Green

Research output: Contribution to journalArticlepeer-review

Abstract

Molecular mechanisms were proposed to account for extraordinary optical activities of polyisocyanates containing chiral moieties (chiral monomer or initiator fragment) reported by Green et al. and by Okamoto et al, where the polyisocyanate molecule was modeled by a helical chain consisting of an alternating sequence of right-handed and left-handed helices with helix reversals in between. Theoretical predictions based on this model were consistent with remarkable dependence of optical rotation on monomer composition for random copolyisocyanates of chiral and achiral monomers and enantiomorphous copolymers and chain length dependence of optical rotation for achiral polyisocyanates with a chiral initiator fragment on the chain end. The helix reversal was shown to be the key factor for all the cases and more frequent for aromatic sidechain polymer poly(m-methyl phenyl isocyanate) than for aliphatic side chain polymers such as poly(butyl and hexyl isocyanate)s.

Original languageEnglish (US)
Pages (from-to)77-84
Number of pages8
JournalPolymer Journal
Volume29
Issue number1
DOIs
StatePublished - 1997

Keywords

  • Chiral
  • Copolymer
  • Helical Conformation
  • Helix Reversal
  • Optical Activity
  • Polyisocyanate
  • Statistical Mechanics

ASJC Scopus subject areas

  • Polymers and Plastics
  • Materials Chemistry

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