ma8b01658_si_003.avi (7.15 MB)
Elastic–Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate
media
posted on 2018-10-31, 13:33 authored by Ran Shi, Tao Lin Sun, Feng Luo, Tasuku Nakajima, Takayuki Kurokawa, Yue Zhen Bin, Michael Rubinstein, Jian Ping GongHydrogels 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.