Synthesis of Cellulose-Based Hydrogels: Preparation, Formation, Mixture, and Modification

Abstract

Cellulose is the most abundant biopolymer, and it has been used in different areas because of its unique properties as various fibril structures and sizes that affecttensile characteristic of the polymer. To increase its features and/or add a new property to cellulose, preparation and modification methods have been deeply investigated and reported. This chapter is classified into four different sections: preparation, formation, mixture, and modifications of cellulose. The preparation method of cellulose (including bacterial cellulose) is important, because it directly effects to fibril formation and structure. In addition to this, depending on usage area, cellulose is necessary to prepare as whisker, fibril, and nano- formations to sustain desired polymer structure. To increase the targeted property of cellulose hydrogel, different kinds of polymers such as polyvinyl alcohol and polyethylene glycol are mixed with cellulose during the preparation of hydrogel. However, cellulose hydrogels still need to improve its physical abilities. Therefore, various modifications have been developed for cellulose and its hydrogel. The most fundamental derivatives are methyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose. In addition to this, in recent years, stimuli-responsive and superabsorbent polymers have become more popular. Swelling behavior ofhydrogels can be changed by pH, temperature, composition of solvent, and electric field in stimuli-responsive polymers that are available to use in pharmaceutical, bioengineering, and tissue engineering areas. Superabsorbent hydrogels have the ability to absorb water up to several hundred times of their dried weight that can be used in bioengineering, agricultural, tissue engineering areas, and sanitary products. The reaction mechanisms and configu- rations of mixtures were clearly illustrated in this chapter. Groundbreaking and latest studies were discussed via the hydrogel properties based on analysis of X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scan- ning calorimetry (DSC), Fourier transformation infrared spectroscopy (FTIR), tensile at break, tensile stress, and Young’s modulus. Keywords