Preparation and characterization of poly(vinyl alcohol)/hydroxylapatite hybrid hydrogels

Poly(vinyl alcohol)(PVA)/hydroxylapatite(HA) hybrid hydrogels used for bioactive artificial cartilage were prepared by compounding in situ with sol-gel synthesis of HA in PVA solution. To draw comparisons, both physical mixing and deposition in situ methods were also used to prepare hybrid hydrogels. The influence of contents and dispersed condition of HA in PVA matrixes on hydrogel's mechanical strength were investigated and compared. The micromorphology and crystalline structure of HA were also observed by some analysis techniques. It was verified that the distinct conglomeration of HA particles in PVA matrixes were overcome using sol-gel in situ methods, and mechanical strength of PVA/HA hydrogels increased obviously compared to deposition in situ and physical mixing methods. HA particles being dispersed uniformly in PVA hydrogels prepared by sol-gel in situ compounding were of crystalline structure, which acted as a kind of heterogeneous nucleating agent improving the crystallization of PVA by depressing the dependence of the crystalline process on the temperature and external factors, hence raising the tensile strength of hybrid hydrogels.