Cellulose pulp, obtained from a paper industry, has been dissolved in PEG/NaOH system and the resulting solution has been polymerized in the presence of monomer acrylic acid (AA) and crosslinker N,N′ methylene bisacrylamide via free radical polymerization. The Cell/PEG/poly (SA) ternary semi-IPN hydrogel, so prepared, was characterized by FTIR and TG analysis. The dynamic water uptake of various hydrogels, having different compositions, was investigated in the physiological buffer of pH 7.4 at 37°C. The various hydrogels exhibited chain-relaxation controlled swelling behavior. The uptake data was best interpreted by Schott kinetic model. The various diffusion coefficients, that is, initial , average , and late time , were also calculated using the dynamic water uptake data. The hydrogels showed fair pH and salt-dependent swelling behavior. 1. Introduction Cellulose is one of the most abundant renewable organic materials with annual production of about 5 × 1011 metric tons [1]. Cellulose is a linear syndiotactic homopolymer composed of D-anhydroglucopyranose units, which are linked by -(1 4)-glycosidic bonds. This biopolymer exhibits some excellent properties such as mechanical robustness, biodegradability, hydrophilicity, and biocompatibility [2]. These properties are mainly responsible for extensive use of cellulose in a wide spectrum of applications that include pharmacy, agriculture, medical science, industries, and so many other related branches. Some of the major applications include water reservoirs in agriculture [3], body water retainers [4], ocular bandages [5], artificial cartilage [6], controlled drug delivery [7, 8], scaffolds for regenerative medicine [9], stomach bulking agents [10], and wound dressings [11]. Most of the applications of cellulose-based hydrogels, mentioned above, exploit water absorption property of cellulose and so it is essential to have full control on the swellability of this biopolymer in these applications. But insolubility of cellulose in water (due to extensive inter- and intramolecular H-bonding between O and H atoms of cellulose) and lack of ionizable functional groups in cellulose backbone are the major barriers that must be crossed to make this polymer useful in various fields. In recent past, several solvent systems have been used for dissolution of cellulose in effective manners. These include NaOH-urea/thiourea system [12] and ionic liquids [13], which are limited to laboratory use only due to volatility, toxicity, and high cost. In addition, the introduction of desired functionality into cellulose backbone
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