Fabrication And Properties Of TiO₂ NanotubesHA/PVDF Composite Coating On Titanium

Titanium and its alloys are commonly used implant materials in clinical bone repair,but due to their biological inertness,they can only form a simple mechanical bond around the bone defect,which is prone to loosening or even failure,so surface modification is often required before use.The research group prepared a TiO₂-BaTiO₃ coating on the surface of the titanium alloy in the early stage.The piezoelectric properties obtained after polarization can promote bone growth and shorten the bone repair cycle.However,barium titanate generated by surface in-situ reaction has a low piezoelectric coefficient,and it is difficult to add bioactive ceramics to the coating.Therefore,in response to the above problems,this study proposes the preparation of titanium dioxide nanotubes?TNT?coating on titanium by anodization,and then spin-coat polyvinylidene fluoride?PVDF?on the TNT coating to obtain a TNT-PVDF coating.The introduction of hydroxyapatite?HA?nanoparticles in the PVDF coating improves its biological properties.The binding force and in vitro biological properties of the coating were characterized,and the effects of HA addition on coating morphology,phase composition,hydrophilicity,and piezoelectric properties were also studied.When the concentration of PVDF solution is 8wt%,the heat treatment temperature is 80?,the polarization voltage is 11kV,and the polarization time is 30min,the content of?-phase PVDF in the TNT-PVDF coating on titanium is the largest,and the piezoelectric coefficient is2.61pC/N.The preparation of TNT coating on titanium can improve the binding force between the PVDF coating and the titanium substrate.The tensile bond strength of the TNT-8%PVDF coating is 8.01MPa,which is 166%higher than that of directly coat the PVDF coating on the Ti surface.Granular depositions appeared on the surface of PVDF coating on the 14th day of SBF immersion,but the surface was covered with apatite on the 14th day of dynamic loading SBF immersion.In addition,the TNT-PVDF coatings on titanium don't have cytotoxicity.After the introduction of HA nanoparticles in the PVDF coating,with the HA addition increases,the hydrophilic property of the coating is improved,and the piezoelectric coefficient decreases first and then increases.When the HA addition is 20wt%,the piezoelectric coefficient is up to 1.53pC/N,and the tensile bond strength of the coating is 8.15MPa.After polarization,the coating was only covered with apatite on the 14th day of SBF immersion,but was completely covered with apatite after 1 day of dynamic loading.In addition,the TNT-HA/PVDF coatings are not cytotoxic and have good cell compatibility.