“…To obtain the network, chemical cross-linking (Denizli, Can, Rzaev, & Guner, 2004;Kiritoshi & Ishihara, 2004;Molina, Gomez-Anton, & Pierola, 2007;Zhao, Liao, Gao, & Liu, 2006), physical entanglement (Saito, Sakurai, Sakakibara, & Saga, 2003), ionic bonds (de la Torre, Torrado, & Torrado, 2003;Kang, Park, Lee, & Son, 2007;Masci, Husu, Murtas, Piozzi, & Crescenzi, 2003;Wong, Díez-Pascual, & Richtering, 2009) and hydrogen bonds (Jin, Liu, Zhang, Chen, & Niu, 2006) are used in the preparation of hydrogels. Polymer hydrogels have been widely utilized as drug delivery, food, cosmetics, high water-absorbing resin, contact lenses, corneal, implant, substitutes for skin, tendons, ligaments, cartilage, and bone, because of their excellent hydrophilicity, permeability, compatibility and low coefficient of friction (Calvert, 2009;Chang, Duan, Cai, & Zhang 2010;Chan, Whitney, & Neufeld, 2009;Liu & Fan, 2005;Yamamoto, Takahashi, & Tabata, 2003).…”