Preparation Of Novel Nano-hydroxyapatite/polylactic Acid Porous Composites

Tissue engineering porous composites have always been one of the hotspots in the field of biomaterials.Polylactic acid is a kind of important biodegradable and biocompatible polymer,but its mechanical strength is insufficient.Nano-hydroxyapatite is a representative bioactive material which is innoxious and harmless,but its bioabsorbability is poor.The combination of these two materials can give full play to their advantages and complement each other to get the ideal tissue engineering porous composites.This paper mainly studies the novel template directed synthesis of hydroxyapatite nanorods and the preparation and properties of its porous composites with polylactic acid.First of all,phosphoric acid with calcium nitrate and sodium hydroxide as raw material,using sodium acetate as a new template,preparing novel nano-hydroxyapatite by reflux-hydrothermal method.The effect of the experimental conditions on the preparation of nano hydroxyapatite was investigated,and the synthesis process was optimized.Using solvent casting/vacuum volatilization/particle leaching method with dioxane as solvent,sodium chloride as porogen,combining the novel nano-hydroxyapatite and polylactic acid to preparing the porous composites.We studied the influence of process parameters,porogen and hydroxyapatite mass ratio on the structure and properties of composite materials.The results showed that the novel nanostructure rod-like hydroxyapatite with good crystallinity was prepared by reflux-hydrothermal method by using sodium acetate as a novel template.The length of the nanorods is about 50～70 nm,and the diameter is about 15～20 nm.The nanorods have holes with a diameter of about 2～7 nm on surface.The specific surface area is 66.066 m2/g,the pore volume is 0.462 cm3/g,and the pore size is concentrated in 2.4,4.3,5.6,7.7 nm.The crystallization of hydroxyapatite can be improved by increasing the hydrothermal temperature,prolonging the hydrothermal time and adding sodium acetate to the template.At the same time,sodium acetate has the function of guiding hydroxyapatite to form hierarchical structure.A novel hydroxyapatite/polylactic acid porous composites was successfully prepared by solvent casting/vacuum volatilization/particle leaching method.It is found that the composites has two-stage pore structure,and the pore size of the composites is controlled by changing the particle size of sodium chloride and the temperature of solvent volatilization.The porosity of the composites is controlled by adjusting the amount of sodium chloride.The addition of hydroxyapatite can improve the hydrophilicity of the composites and significantly improve the mechanical strength of the composites.