Structure and applications of poly(vinyl alcohol) hydrogels produced by conventional crosslinking or by freezing/thawing methods

Poly(vinyl alcohol) (PVA) is a polymer of great interest because of its man y desirable characteristics specifically for various pharmaceutical and bio medical applications. The crystalline nature of PVA has been of specific in terest particularly for physically crosslinked hydrogels prepared by repeat ed cycles of freezing and thawing. This review includes details on the stru cture and properties of PVA, the synthesis of its hydrogels, the crystalliz ation of PVA, as well as its applications. An analysis of previous work in the development of freezing and thawing processes is presented focusing on the implications of such materials for a variety of applications. PVA blend s that have been developed with enhanced properties for specific applicatio ns will also be discussed briefly. Finally, the future directions involving the further development of freeze/thawed PVA hydrogels are addressed.