Fabrication and characterization of poly(vinyl alcohol)/chitosan hydrogel thin films via UV irradiation

• Published in: European polymer journal Vol. 49; no. 12; pp. 4201 - 4211
• Main Authors: Nguyen, Ngoc-Thang, Liu, Jui-Hsiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-12-2013; Elsevier
• Subjects: Applied sciences; Biomedical applications; Chitosan; Crosslinking and degradation; Exact sciences and technology; Hydrogel thin films; Physicochemistry of polymers; Poly(vinyl alcohol); Polymers and radiations; Ultraviolet irradiation; Poly(vinyl alcohol); Biomedical applications; Chitosan; Ultraviolet irradiation; Hydrogel thin films; Acrylic acid copolymer; Photochemical crosslinking; Swelling; Acrylic acid; Vinyl alcohol copolymer; Experimental study; Colloidal gel; Polyelectrolyte; Polyvinylalcohol; Morphology; Preparation; Reaction mechanism; pH; Oside polymer; Kinetics
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2013.09.032

•Reversible swelling and pH-responsive PVA/chitosan films were fabricated.•The gel fraction and swelling degree of the hydrogels can be tuned.•The uniform interporous structures have been observed throughout the films.•A gradient in the crosslinking density through the film thickness was observed.•The interporous hydrogels can be used for the synthesis of silver nano-particles.
A series of poly(vinyl alcohol)/chitosan (PVA/CTS) hydrogel thin films were prepared via ultraviolet (UV) irradiation, with acrylic acid (AA) monomer added as a crosslinker without the addition of any other photo-initiator. The swelling behaviors, intermolecular chemical bonds, molecular structures, thermal behaviors, degrees of crystallinity, morphologies of the surfaces and internal structure, and their relationship to the AA content were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Poly(acrylic acid) (PAA) and its chemical crosslinks formed in hydrogel films via free-radical reactions were confirmed using FTIR and DSC analyses. The XRD patterns indicated that the degree of crystallinity of the hydrogel films decreased as the PAA content was increased. SEM micrographs showed that a uniform interconnected pore structure was formed through the entire hydrogel structure, and a gradient in the crosslinking density through the film thickness was observed to result from extended irradiation times. The swelling behaviors revealed that the formation of PAA and its crosslinking in the hydrogel thin films improved the pH stability and controlled the degree of swelling while retaining a high swelling rate. The successful formation of chemical crosslinking without any specific photo-initiator improves the natural characteristics of CTS and PVA and imparts the resulting PVA/CTS hydrogel thin films with properties that make them very promising in biomedical applications.