| Polyvinyl alcohol（PVA）hydrogel is a polymer material with three-dimensional network structure.It has porous structure and high biocompatibility.It has a good prospect in the field of cartilage repair,but due to its poor swelling properties and biological tribological properties,Its application in practice is limited.Therefore,it is very important to study hydrogels with good swelling property and water content as well as friction and wear properties.In this paper,PVA-PEG/BA hydrogel was prepared by freeze-thaw cycle.Adding polyethylene glycol（PEG）and boric acid（BA）can fully enhance the swelling and biotribological properties of hydrogels.The effects of different BA content and different freezethaw cycles on the three-dimensional morphology and internal pore size of PVA-PEG/BA hydrogel were studied.Compared with natural articular cartilage,the hydrophilic and swelling properties of PVA-PEG/BA hydrogels under different preparation conditions were studied.The wear amount of hydrogels was tested under different experimental conditions,and the changes of wear properties and average surface roughness were analyzed.The main experimental conclusions are as follows:（1）PVA-PEG/BA hydrogel has an internal porous structure similar to that of natural articular cartilage.With the increase of boric acid content,the pore size of the hydrogel gradually decreases,and the number and density of pores increase.This structure is conducive to the storage of water molecules inside the hydrogel,and also strengthens the bonding strength with the articular cartilage surface.（2）PVA-PEG/BA hydrogel has good swelling property and hydrophilic property.The swelling ratios of three kinds of hydrogels reach swelling equilibrium state at about 24 h.the water content of the hydrogel was 69%,68% and 63%,respectively.It is kept within the normal water content of articular cartilage（60% ～ 80%）.The lower the average surface roughness of the hydrogel with higher BA content,and the roughness of the three hydrogel with different BA content is smaller than that of the normal cartilage（1～5μm）.（3）PVA-PEG/BA hydrogel has good lubricity in calf serum environment,with an average surface roughness of 1.074μm,the wear degree of hydrogel is directly proportional to rotational speed and load.With the increase of rotational speed and load,the pits of wear center of the hydrogel are more obvious,the number of convex peaks on the worn surface decreases,and the average surface roughness increases.Although the water content of the hydrogels with BA content of 2% decreases,the wear resistance is better,and the average surface roughness is close to that of the normal articular cartilage.It is expected to be used as biomimetic articular cartilage material in artificial joints. |
