Preparation And Characterization Of Strengthened Nanocomposite Hydrogels

Polymer hydrogels, consisting of a three-dimensional network, are formed by covalent bond, hydrogen bond or van der waals force reaction, which can swell but dissolve. In recent years, various types of polymer hydrogels have been widely studied in many fields, especially in the biomedical engineering field, mainly because of their resemblance on structure and properties to the organism tissue. However, the mechanical property of ordinary hydrogels is very poor, which extremely limit the application of hydrogels in tissue regeneration or as tissue engineering scaffolds.In this paper, two kinds of biocompatible hydrogels with improved mechanical properties were prepared. One is polyvinylpyrrolidone/clay (PVP/clay) organic-inorganic nanocomposite hydrogels prepared by using hectorit type clay---aponite XLG as crosslinker and reinforcing agent. The other one is polyacrylamide/bacterial cellulose (PAAm/BC) composite hydrogel in which polyacrylamide was introduced into the network of bacterial cellulose. The structure and properties of the two kinds of hydrogels were studied.For PVP/clay hydrogel, the maximum stress and modulus could reach as high as 3.5MPa and 2.7MPa respectively when strain is 80%, and the modulus, which is obvious higher than that of normal hydrogels. The reactive mechanism of PVP/clay polymerization had also been studied. With all the test results, we deduced that initiation reaction accured in the solution but on the surface of clay sheet, which is totally different to that of Polyamide/clay system. Morphology of cartilage cells cultured on the surface of hydrogels showed preliminary that the hydrogel didn't have obvious negative affection on the cell growth.For PAAm/BC composite hydrogel, it is found that there was strong hydrogen bond interaction between polyacrylamide and bacterial cellulose, which avoided PAAm dissolving out of the BC even without crosslinker. The compression strength and modulus of PAAm/BC composite hydrogels improved greatly comparing with the pure BC.For the last part, the preparation of nanocomposite hydrogel with ordered structure was explored by using the method of electrospinning, by which the obtain the hydrogel have orientation structure and improved mechanical property.