Hydrogel formation from the concentrated aqueous solution of polyvinyl alcohol
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Hydrogel formation from the concentrated aqueous solution of polyvinyl alcohol Tomoyo Sakaguchi1, Suong-Hyu Hyon2, Kazuaki Matsumura1 1
School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 Japan
2
Center for Fiber and Textile Science, Kyoto Institute of Technology, Japan
ABSTRACT Physically crosslinked polyvinyl alcohol (PVA) hydrogels with high mechanical properties can be made by a low temperature crystallization method using a mixed solvent of dimethyl sulfoxide (DMSO) and water. Such hydrogels are studied as the artificial articular cartilage material. But DMSO shows cytotoxycity, and it is also have the effect of accelerating the absorption of harmful substances. Therefore completely elimination must be required for clinical application but the process is difficult. However, PVA hydrogel made by water as a sole solvent by freeze-thawing method became cloudy because of micro-heterogeneous structure, and shows low mechanical properties. Therefore, in this study, we developed the novel hot pressing method for preparing transparent and uniformly cross-linked PVA hydrogels without DMSO from highly concentrated aqueous solution. By this method, PVA hydrogels with high mechanical property and high transparency can be obtained without any harmful organic solvent because of the fast crystallization even at room temperature. The mechanical properties of PVA hydrogels were remarkably depended on their water contents after gelation, regardless of solution concentration.
Introduction Poly (vinyl alcohol) (PVA) hydrogel is an excellent artificial articular cartilage repair material due to its biocompatibility and biotribological properties. The artificial joint operation that is one of the treatment of the joint cartilage disease is an effective clinical cure. PVA hydrogel is material, which was first advanced as a synthetic articular cartilage material by Bray and Merrill in 1973 [1]. Since then, a number of approaches have been utilized to demonstrate the utility of PVA hydrogels [2,3]. Physically crosslinked PVA hydrogels prepared using a freeze–thawing method [4] have been extensively studied to improve their mechanical strength. Much more tough and transparent PVA gels can be prepared using a quench method in a solvent mixed with DMSO and water [3,5]. However, the process to obtain a DMSO–water mixed solvent is neither simple nor safe. In this study, we tried to make PVA hydrogel with high mechanical
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properties without DMSO by hot pressing hydrogelation method with high concentrated PVA aqueous solution.
Experimental PVA hydrogel preparation- Low temperature crystallization method PVA, with a viscosity-average degree of polymerization of 1700 and a degree of saponification of 99.7 mol % (Japan VAM & POVAL Co., Ltd., Osaka, Japan), was dissolved in a solvent mixture of DMSO and H2O with weight ratio of 80/20 at 120oC and the solution (PVA concentration was 10% by wt) was poured between two brass plates with 3 mm thick spacer and cooled to -20oC
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