Multi-structural network design and mechanical properties of graphene oxide filled chitosan-based hydrogel nanocomposites

Chitosan (CS), a linear natural polysaccharide, is often chosen to prepare hydrogels due to its hydrophilic nature and biocompatible merits. However, mechanically weak CS-based hydrogels show limited applications. Herein, we show a new multi-structural network design for mechanically enhancing graphene oxide (GO) filled CS-based hydrogel nanocomposites. The designedmulti-structural hydrogel network shows a relatively dense structure with surrounding polymer chains at the local zone of self-assembledGO-CS units and a relatively loose structure at the far zone, resulting in the mechanical enhancement. By tuning GO loading and molecular weight of CS in a specific range, we intend to understand the effect of the specific multiple network structures on the mechanical properties of the composites. The experimental results demonstrate that themulti-structural network design provides an effective reinforcement mechanism for the hydrogel composites. The composite (containing only 0.30 wt% GO and approximate to 90 wt% water) has achieved 163% and 91% increases in compressive strength and work of compression, respectively, comparing to those of the neat gel. The findings may be generally applicable for the structural design and understanding of nanofiller-reinforced hydrogel and elastomer composites. (C) 2018 Elsevier Ltd. All rights reserved.