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Indexed by:期刊论文

Date of Publication:2018-11-13

Journal:MACROMOLECULES

Included Journals:SCIE、Scopus

Volume:51

Issue:21

Page Number:8887-8898

ISSN No.:0024-9297

Key Words:Biomolecules; Biopolymers; Chitosan; Elastoplasticity; Hyaluronic acid; Hydrogels; Hysteresis; Ionic strength; Polyelectrolytes; Sodium; Stress relaxation; Tensile strain; Tensile testing; Yield stress, Charge composition; Cyclic tensile tests; Mechanical behavior; Negatively charged; Polyelectrolyte complexation; Polyelectrolyte complexes; Strain and strain rates; Synthetic polyelectrolyte, Strain rate

Abstract:Hydrogels formed by polyelectrolyte complexation (PEC) of oppositely charged biopolymers, free of any chemical additives, are promising biomaterials. In this work, the mechanical behavior of hydrogels consisting of positively charged chitosan and negatively charged sodium hyaluronate (HA) at balanced charge composition is investigated. These hydrogels exhibit strong tensile strain and strain rate dependence. They are elastic-like, independent of the strain rate at small strain, but exhibit plastic-like behavior above the yield point by showing a monotonous decrease of the stress. The cyclic tensile test demonstrates that these hydrogels exhibit small and quickly recoverable hysteresis in the elastic-like region but large and partially recoverable hysteresis above the yield point. The stress relaxation experiment shows a plateau in the reduced stress followed by an abrupt fracture, and the time to failure decreases exponentially with increasing applied step strain. Such elastic-to-plastic-like transformation of the biopolymer PEC gels is quite different from the behaviors of PEC hydrogels formed by oppositely charged vinyl-type synthetic polyelectrolytes due to the difference in flexibility, charge density, and ionic bond strength of these polymers.