Poly(methyl methacrylate)-silica-calcium phosphate coatings for the protection of Ti6Al4V alloy

Poly(methyl methacrylate) (PMMA)-silica coatings modified with calcium phosphates (CaPs) in the form of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) have been developed to improve the corrosion resistance and bioactivity of Ti6Al4V titanium alloys, applied in medical and dental implants. PMMA-silica hybrids containing 1000 ppm HA or beta-TCP were prepared by combining the sol-gel reactions of tetraethylorthosilicate (TEOS) with the radical polymerization of methyl methacrylate (MMA) and 3-methacryloxypropyl trimethoxysilane (MPTS), used as molecular coupling agent. Bi-layer coatings about 15 mu m thick, deposited by immersion on Ti6Al4V, are homogeneous, defect-free, and exhibit strong adhesion to the substrate (>14 MPa). The addition of HA and beta-TCP led to a slight increase in thermal stability, without affecting the structural integrity of the highly crosslinked PMMA-silica matrix. The greater hydrophilicity and surface roughness of coatings containing HA and beta-TCP are associated with the size and chemical composition of CaPs, necessary for effective osteointegration. The modified coatings showed high anti-corrosion efficiency with low-frequency impedance modulus values of up to 73 G Omega cm(2), remaining stable after 150 days of exposure to simulated body fluid (SBF) solution. [GRAPHICS] .

Automated summary

Poly(methyl methacrylate) (PMMA)-silica coatings modified with calcium phosphates (CaPs) were developed to enhance the corrosion resistance and bioactivity of Ti6Al4V titanium alloys for medical and dental implants. The addition of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) improved the thermal stability and hydrophilicity of the coatings, contributing to effective osteointegration. The modified coatings exhibited high anti-corrosion efficiency and remained stable in simulated body fluid (SBF) solution after 150 days of exposure.