Wollastonite-Poly(Ethylmethacrylate-Co-Vinylpyrrolydone) Nanostructured Materials: Mechanical Properties and Biocompatibility

摘要

Synthetic pseudowollastonite (psW) and a nanostructured copolymer made of a biostable component, Poly(ethylmethacrylate) (PEMA) and a bioresorbable component, vinylpyrrolidone (VP) are used in this work for the preparation of a new family of bone substitutes that allow osseointegration and mechanical stability. Composites are prepared by bulk polymerization of the desired composition in 15 mm diameter cylindrical plastic moulds. Polymerization was induced thermally at 50°C using 1wt% azobis(isobutyronitrile) (AIBN) as free-radical initiator. The moulds were filled to a height of 100 mm and 1 mm height discs were cut with a diamond saw. Specimens with a ceramic/polymer ratio 58/42, 33/67,17/83 and 0/100 were obtained. Compression stress in the range 39-59 MPa and elastic modulus between 2.64 and 4.14 GPa are obtained where the greater values correspond to the specimens prepared with a 60% ceramic load. Degradation in SBF produces a porous nanostructure in the polymeric component indicating microdomains of different solubility and the formation of an apatite-like layer on the surface of the wollastonite component. All the compositions assayed present a biocompatibility at least of the level or even superior than the Thermanox control used.