表面效应对生物活性PDMS-SiO _ 2 - CaO-P _ 2O _ 5骨再生材料降解机制的影响

Abstract(#br)The purpose of this work is to study the dissolution mechanism of SiO 2 -based bioactive hybrid materials containing both CaO and P 2 O 5 in their structures and to determine the influence of apatite crystallization over the surface features of the hybrids during degradation. Hybrid materials were synthesized using sol–gel method. Tetraethoxysilane (TEOS), hydroxyl terminated polydimethylsiloxane (PDMS), Ca(NO 3 ) 2 ·4H 2 O, and triethyl phosphate (TEP) were used as reactants. The degradation and bioactivity of the hybrid materials were tested by soaking the specimens into simulated body fluid (SBF). Raman spectroscopy, tensiometry and N 2 adsorption/desorption curves were used to measure the changes during the degradation experiments. Several mathematical approaches have been taken to analyze the results. The growth of an apatite layer on the surface of SiO 2 -modified PDMS-P 2 O 5 -CaO hybrid materials occurs together with degradation of the silica-based matrix. The dissolution kinetics depends upon the composition of the material. It varies from a surface-driven mechanism in the case of low-P 2 O 5 samples to a degradation path which fits into a Weibull type kinetic model, typical of matrix dissolution processes in materials enriched in P 2 O 5 . During degradation, the surface parameters, fractal constant and anisotropy of the pores were determined. The slight increase of the fractal constant in low-containing P 2 O 5 materials suggests the formation of a homogeneous silica-like layer in the first stage of degradation, which also works as anchoring nucleus for subsequent apatite formation. In all the cases, the degradation leads to ink-bottle shaped pores, increasing their volume as degradation occurs, but keeping their neck shape.