Structural rearrangement and stiffening of hydrophobically modified supramolecular hydrogels during thermal annealing

Chao Wang, Clinton G. Wiener, Yiming Yang, R. A. Weiss, Bryan D. Vogt

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Dynamic crosslinks formed by thermoreversible associations provide an energy dissipation mechanism to toughen hydrogels. However, the details of the organization of these crosslinks impact the hydrogel properties through constraints on the network chain conformation. The physical crosslinks generated by hydrophobic association of the 2-(N-ethylperfluorooctane-sulfonamido)ethyl methacrylate (FOSM) groups in a random copolymer of N,N-dimethylacrylamide (DMA) and FOSM provide a simple system to investigate how the hydrogel structure (as determined from small angle neutron scattering impacts the mechanical properties of the hydrogel. The initial hydration of the copolymer at 25 °C leads to a kinetically trapped structure with large-scale heterogeneities. Heating the hydrogel at 60 °C, which is above the glass transition temperature for the FOSM domains, allows the hydrogel structure to rearrange to reduce the density of network defects and the structural heterogeneities. That effectively increases the crosslink density of the network, which stiffens the hydrogel and decreases the swelling at equilibrium at 25 °C. The processing history determines how the hydrophobes aggregate to form the physically crosslinked network, whose structure defines the mechanical properties of these hydrogels.

Original languageEnglish (US)
Pages (from-to)1036-1044
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume55
Issue number13
DOIs
StatePublished - Jul 1 2017

All Science Journal Classification (ASJC) codes

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

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