Preparation And Properties Of Polyvinyl Alcohol/hydroxyapatite Composite Hydrogel

Hydrogel materials have been widely studied since the 1960 s due to their strong hydrophilicity,high water content,good biocompatibility,certain film-forming properties,mechanical properties and elasticity.Polyvinyl alcohol(PVA)matrix hydrogels have been a research hotspot of hydrogel materials,by reason of the chain structure of raw material PVA is simple,regular and contains a large amount of hydroxyl.Due to the properties of easy to form,nontoxic and chemically stable,PVA hydrogels are widely used in garden agronomic,daily chemical,environmental protection,food industry and other fields.In addition,PVA hydrogels also have excellent biocompatibility and degradability,which are regarded as an ideal biological material,having a strong application prospect in the field of biomedicine.At present,the research on PVA hydrogel has broken through the limitation of single matrix and technology.To overcome the shortcomings of single hydrogel in mechanical properties and biological activities,and give them new properties,PVA matrix is compounded with other ingredient,such as natural polymers,synthetic polymers and nanoparticles,to expand the application possibilities.In this study,in-situ synthesis was used to synthesize hydroxyapatite(HA)nanoparticles in PVA aqueous solution,using cyclic freezing-thawing(F/T)and irradiation crosslinking to form PVA/HA composite hydrogel.The structure,mechanical properties,crosslinking degree and biological activity of the composite hydrogel were evaluated.The research results are as follows:1.A series of PVA/HA composite hydrogels were prepared by in-situ synthesis combined with cyclic F/T forming techniques.The interaction mechanism between PVA and HA in in-situ synthesis at the pH value of 10 was discussed.The porous structure,mechanical properties,water content and water absorption of the composite hydrogel could be regulated by changing the contents of matrix PVA and HA.The effects of pH values on the structure and properties of the composite hydrogels were investigated by adjusting the pH of the system to 7 before cyclic F/T.2.A series of bi-crosslinking PVA/HA hydrogels were synthesized by combining irradiation crosslinking with cyclic F/T.We discussed the formation mechanism,and the effect of electron beam irradiation dose on the crosslinking degree and mechanical properties of bi-crosslinking composite hydrogels.The results showed that the increase of irradiation dose would promote the structure of PVA/HA composite hydrogel to be denser,enhancing the crosslinking degree and tensile strength.However,when the irradiation dose was too high,the degradation effect became gradually obvious,resulting in a reduction in the tensile strength and crosslinking degree of the composite hydrogel.3.The bi-crosslinking PVA/HA hydrogels were carried out in vitro SBF culture.The interaction between SBF and the composite hydrogel was analyzed.The changes of structure,morphology,water content and tensile strength of composite hydrogels under different culture time were investigated.In the process of culture,the crystal structure of HA was further improved,the PVA skeleton was gradually thickened,and the porosity was gradually reduced.PVA/HA composite hydrogel has high stability in SBF,can maintain certain water content and tensile strength,which is expected to be applied in the field of bone tissue engineering.