Mechanical strength, of hydrogels

The equilibrium swelling degree is the most important property of a hydrogel it directly influences the rate of water sorption, the permeability to drugs, and the mechanical strength of the gel. It also affects the biocompatibility of the... 

Shah, N. H., Railkar, A. S., Phuapradit, W., Zeng, F. W., Chen, A., Infeld, M. H., and Malick, A. W. (1996), Effect of processing techniques in controlling the release rate and mechanical strength of hydroxypropyl methyl cellulose based hydrogel matrixes, Eur. J. Pharm. Biopharm., 42,183-187. 

Shah N, Railkar AS, Phuapradit W, Zeng FW, Malick AW. Effect of processing techniques in controlling the relca.se rate and mechanical strength of hydroxypropyl methylcellulose based hydrogel matrices. Eur J Pharm Biopharm 1996 42(3) 183-7. 

Poly(vinyl alcohol) (PVA) is one of the hydrogels most often used in biomaterial applications. Because of the presence of excessive hydroxyl groups, PVA contained a significant amount of water. PVA was also claimed to have good mechanical strength. Another hydrogel, poly(2-hydroxyethyl methacrylate) (poly-HEMA), is well known for its excellent biocompatibility. xhe versatile biomedical applications of poly-HEMA are demonstrated by its uses in contact lenses, vitreous humor replacements and suture materials. To explore a new formulation and other usages of these two pol ers, we have copolymerized HEMA with PVA-MA (PVA esterified with maleic anhydride), the preparation and properties of this copolymer are discussed in this article. 

Although the feasibility of aqueous lubrication with elastomers and hydrogels has been established, the poor mechanical properties and wear resistance of soft materials have been limiting factors for applications. However, it has been shown that the mechanical properties of hydrogels can be improved to a similar level as those of elastomers 17). Thus, there is hope that hydrogels can be used in applications where mechanical strength is required. The practical implementation of biomimetic, aqueous lubrication approaches may become a reaUty in the not-too-distant future. 

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