Stress reduction in phase-separated, cross-linked networks: Influence of phase structure and kinetics of reaction

Caroline R. Szczepanski, Jeffrey W. Stansbury*

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

A mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed through ambient, photo-initiated polymerization-induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three nonreactive, linear prepolymers (poly-methyl, poly-ethyl, and poly-butyl methacrylate). At higher prepolymer loading levels (10-20 wt %), an enhanced reduction in both shrinkage and polymerization stress is observed. The onset of gelation in these materials is delayed to a higher degree of methacrylate conversion (â̂15-25%), providing more time for phase structure evolution by thermodynamically driven monomer diffusion between immiscible phases prior to network macro-gelation. The resulting phase structure was probed by introducing a fluorescently tagged prepolymer into the matrix. The phase structure evolves from a dispersion of prepolymer at low loading levels to a fully co-continuous heterogeneous network at higher loadings. The bulk modulus in phase-separated networks is equivalent or greater than that of poly(TEGDMA), despite a reduced polymerization rate and cross-link density in the prepolymer-rich domains.

Original languageEnglish (US)
Article number40879
JournalJournal of Applied Polymer Science
Volume131
Issue number19
DOIs
StatePublished - Oct 5 2014

Keywords

  • morphology
  • phase behavior
  • photopolymerization
  • structure-property relations

ASJC Scopus subject areas

  • Chemistry(all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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