Characterization of the network properties of poly(ethylene glycol)-acrylate hydrogels prepared by variations in the ethanol-water solvent composition during crosslinking copolymerization

Nathan Ravi, Arpita Mitra, Paul Hamilton, Ferenc Horkay

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

The characteristics of poly(ethylene glycol) (PEG)-acrylate hydrogel networks were investigated as a function of the ethanol-water solvent composition during free-radical crosslinking copolymerization. Macromonomer (88% ω-methoxy-PEG-acrylate and 10% ω-phenoxy-PEG-acrylate) and crosslinker (2% PEG-diacrylate) concentrations were kept constant. As the copolymerization progressed, the polymer solution in 100% ethanol became increasingly turbid, indicating the development of a heterogeneous network structure. In 100% water, however, the initially turbid polymer solution became increasingly transparent as the crosslinking copolymerization progressed. All the gels were optically clear upon equilibration in water. Kinetic studies, with attenuated total reflectance-infrared, showed a long induction period, along with a lowered reaction rate, in 100% ethanol, and a decrease in conversion with an increase in ethanol content. These results agree with the UV analysis of the sol fractions, which indicated an increase in the amounts of unreacted PEG-acrylates with an increase in the ethanol content. The gels which were formed with a high ethanol concentration exhibited lower Young'S modulus and higher swelling ability, suggesting that the network structure was significantly affected by the solvent composition during free-radical crosslinking copolymerization. From the stress-strain and swelling experiments, the Flory-Huggins interaction parameter was evaluated. The creep characteristics of the hydrogels were modeled with two Kelvin elements.

Original languageEnglish
Pages (from-to)2677-2684
Number of pages8
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume40
Issue number23
DOIs
StatePublished - Dec 1 2002

Keywords

  • Copolymerization
  • Crosslinking
  • Kinetics (polym.)
  • Mechanical properties
  • Mixed solvent
  • Poly(ethylene glycol)-acrylate hydrogels

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