Self-healable and pH-sensitive high-strength water-soluble chitosan/chemically cross-linked polyvinyl alcohol semi-IPN hydrogel

A kind of novel unique semi-IPN was formed through facile radical cross-linking reaction between PVA-based macromonomer (PVAM) and acrylic acid (AA) in the presence of water-soluble chitosan (WSC). WSC, PVAM and AA were dissolved in distilled water, mixed homogeneously and initiated with potassium persulphate to perform the reaction. WSC was well distributed within the chemical network, which enabled the hydrogen bonding to be formed between part of amino groups on WSC chain and some carboxylic groups on PVA-based gel. As a result, the tensile strength of WSC/PVAM-AA semi-IPN is as high as 625 MPa when 30 wt% WSC was fed. Both the WSC content and water content affected the mechanical properties of the semi-IPN. Hydrogen bonding imparted another characteristic, i.e. self-healing ability, to the semi-IPN. The functional groups including amino and carboxyl groups not only acted as the contributors of hydrogen bonding, but also provided the semi-IPN the third trait, pH-sensitive swelling behavior. As a result, the facilely prepared semi-IPN exhibited triple functions. (C) 2019 Elsevier B.V. All rights reserved.