Super-strong and anti-tearing poly(vinyl alcohol)/graphene oxide nano-composite hydrogels fabricated by formation of multiple crosslinking bonding network structure

As load-bearing material in biomedical-applications as cartilage replacement, artificial meniscus and ten -dons, etc., poly(vinyl alcohol) (PVA)/graphene oxide (GO)-tannic acid (TA) nano-composite hydrogels with multiple-crosslinking network were fabricated by establishing freezing/thawing-annealing-swelling method. By TA anchoring, PVA molecules were grafted onto GO surface efficiently, and strong interfacial interaction led to exfoliation and uniform distribution of GO in matrix. By introducing annealing process, the crystallinity and crystallite size of PVA increased and introducing GO-TA led to more perfect and den -ser crystalline structure, while physical crosslinking network centered on GO-TA and hydrogen bond -abundant crystalline phase formed, resulting in increasing crosslinking density of hydrogel. By further swelling in CaCl2 aqueous solution, hydroxyl-Ca(2+)coordination formed, and multiple-crosslinking net-work was constructed with high crosslinking density. The tensile strength and fracture toughness of com-posite hydrogel were remarkably improved, reaching 14.38 MPa/27.93 MJ/m(3), approximately 11-/26-fold higher than those of neat PVA hydrogel, while tearing strength was significantly enhanced, attributed to high energy dissipation through unzipping multiple interactions. (C) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.