Development of reversibly compressible feather-like lightweight Chitosan/GO composite foams and their mechanical and viscoelastic properties

Three-dimensional (3D) porous materials gain considerable attention in electronics and biomedical/environmental engineering owing to their high porosity, large surface area, and controllable morphological and mechanical properties. In this work, reversibly compressible feather-like lightweight 3D chitosan/graphene oxide (CS/GO) composite foams were prepared with varying the composition ratios of CS to GO using a freeze-drying method. Their structure was obtained via amide linkage formation between the CS amine groups and GO carboxylic acid groups throughout the foam. Chemical analysis of the foams was performed using Fourier-transform infrared spectroscopy, and their morphology was analyzed by field-emission scanning electron microscopy and crosslinking density measurements. Their mechanical features and static and dynamic viscoelastic properties were characterized by monotonic compression, stress-relaxation, and frequency sweep tests using a custom-built micro-indenter and dynamic mechanical analyzer. With increasing the CS concentration, their storage/loss modulus and crosslinking density increased, while their tan delta decreased. Their viscoelastic properties predicted using the proposed modified micromechanics models agreed with the experimental data. This study demonstrates a simple strategy to produce lightweight porous 3D CS/GO composite foams with biocompatibility, electrical conductivity, and decent mechanical and viscoelastic properties regulated by the composition. These foams are promising materials applicable in biomedical and environmental engineering and electrical devices. (C) 2019 Elsevier Ltd. All rights reserved.