A review on carboxylic acid cross-linked polyvinyl alcohol: Properties and applications

Polyvinyl alcohol (PVA) is a nontoxic, biodegradable, and biocompatible polymer and has been used extensively in various fields. Indeed, important features of PVA such as its film-forming ability, high tensile strength and flexibility, high viscosity, solvent tolerance ability, thermostable nature have made it vital and drawn the attention of scientific community. However, being a water-soluble polymer, some chemical modifications are required to alter this property of PVA. Cross-linking is the most attractive and widely used method to change the properties of PVA to make it more valuable material. Different carboxylic acids have already been used for PVA cross-linking in various applications such as pervaporation, reverse osmosis (RO), wound dressing, drug delivery, and fuel cells. However, a comprehensive study on structure-property correlation of carboxylic acids as PVA cross-linker is not available. In this review, different available studies on carboxylic acid cross-linked PVA are summarized and are used to develop structure-property correlations of carboxylic acids as cross-linker on the properties of cross-linked PVA. Advantages and limitations of different carboxylic acids as PVA cross-linker are also summarized for various fields such as tissue engineering, wound dressing, drug delivery, fuel cell/solid polymer electrolyte, pervaporation, desalination and RO solid polymer electrolytes, and food packaging.