Toughening Double Network Hydrogels by Polyelectrolytes.

Abstract

Hoffmeister effect of inorganic salts has been verified as a promising way to toughen hydrogels, however, the high concentration of inorganic salts may accompany by poor biocompatibility. In this work, for the first time, we find that polyelectrolytes can obviously elevate the mechanical performances of hydrogels through Hoffmeister effect. The introduction of anionic poly(sodium acrylate) (P(iAA)) into poly(vinyl alcohol) (PVA) hydrogel induces the aggregation and crystallization of PVA to boost the mechanical properties of the resulting double network hydrogel: elevation of 73, 64, 28, 135, and 19 times in the tensile strength, compressive strength, Young's modulus, toughness, and fracture energy compared with poly(acrylic acid) (PAA), respectively. It is noteworthy that the mechanical performances of the hydrogels can be flexibly tuned by the variation of polyelectrolyte concentration, ionization degree, relative hydrophobicity of the ionic component and polyelectrolyte type in a wide range. This strategy is verified to work for other Hoffmeister effect-sensitive polymers and polyelectrolytes. Also, the introduction of urea bonds into polyelectrolytes can further improve the mechanical properties and anti-swelling capability of hydrogels. As a biomedical patch, the advanced hydrogel can efficiently inhibit hernia formation and promote the regeneration of soft tissues in abdominal wall defect model. This article is protected by copyright. All rights reserved.