Effects of Freezing-Thawing Cycles on Mechanical Strength of Poly (Vinyl Alcohol) Hydrogels

Poly (vinyl alcohol) (PVA) hydrogels are widely used in biomimetic cartilage materials for its good biocompatibility and super shock absorbing properties. However, the small pore size, in general, a few micrometers, of pure PVA hydrogels prepared through freezing-thawing method can not provide the suitable microenvironment for the proliferation of chondrocytes, restricting the application of hydrogels in artificial cartilage. In order to solve this barrier, here, agarose is introduced as porogen to prepare the macroporous PVA hydrogels through freezing-thawing method. The obtained PVA hydrogel have the pore size of 20–200 μm, and macropores have good connectivity. The mechanical properties of the macroporous hydrogels are tested using uniaxial compression and tension experiments and the results show that the mechanical properties of macroporous PVA hydrogels are dependent on the preparation parameters, e.g. the duration of freezing, number of freezing-thawing cycles and the temperature of thawing. After optimization, the mechanical properties of the macroporous PVA hydrogels are closer to those of natural articular cartilage and the obtained hydrogels may be used as the artificial replacement materials.