Preparation Of Hollow Aluminum Phosphate And Hollow Iron Phosphate Spheres

In recent years, there has been more and more interest in study of inorganic hollow nanospheres because of their unique characteristic, high specific surface area and their important application prospect in paint, adsorbent, controlled release of drug, etc.This paper mainly studies the synthesis of hollow aluminum phosphate spheres and iron phosphate spheres through in-situ adsorption-homogeneous precipitation method and homogeneous precipitation-adsorption method by using polystyrene and emulsified paraffin wax as template. The principle of preparation is that the organic/inorganic composite microspheres with core/shell structure are prepared firstly via electrostatic attractive force between the aluminum phosphate or iron phosphate spheres and template spheres, then the templates(core) are removed by using solvents to dissolve or by calcining at high temperature, finally, the hollow inorganic microspheres are synthesized. The products were characterized by SEM, TEM, FT-IR, XRD, TG-DSC, and particle size analysis method. The main research contents and results are as following:1. The synthesis of polystyrene (PS) template。The polystyrene spheres which carried anionic charge on surface were synthesized by soap and soap-free emulsion polymerization method using KPS as initiator and PVP as dispersant. Results show that the PS spheres prepared by soap-free emulsion polymerization method has uniform particle size, the median diameter (D50) is0.15μm, the Zeta potential is-12.3mV. While SDS was used as emulsifier, the PS spheres prepared by soap emulsion polymerization method has non-uniform particle size, the particle size range from0.11to61.21um, the D50is0.15um, Zeta potential is-17.3mV.2. The synthesis of emulsified paraffin template. Using emulsifier R and SDS as compound emulsifier, polyvinyl alcohol(PVA) as stabilizer, the emulsified paraffin with negative charge on surface was synthesized by one-step process. The mass ratios were as following:paraffin wax:R/SDS:PVA: waterproofing agent T:water=30:8:2:0.1-2:58-59.9. The median particle diameter D50is13.3μm, particle size is in the range of5to15μm, the Zeta potential is-18.6mV.3. The hollow aluminum phosphate spheres with uniform size and regular morphology were prepared through in-situ adsorption-homogeneous precipitating method by using PS spheres as template. The diameter and shell thickness of hollow spheres are150nm and30nm, respectively, the BET specific surface area of aluminum phosphate hollow spheres increases with the increasing of template amount, the maximum surface area is21.102m2/g. When the mass ratio of PS to aluminum phosphate is1:2, the aluminum phosphate hollow spheres shows the best morphology.4. The iron phosphate hollow spheres with uniform size were also synthesized through in-situ adsorption-homogeneous precipitation method by using PS spheres as template. The diameter and shell thickness of prepared hollow particles are about150nm and50nm respectively.5. using emulsified paraffin as template, the aluminum phosphate hollow spheres were also synthesized by in-situ adsorption-homogeneous precipitation method and homogeneous precipitation-adsorption method. The median particle diameter and shell thickness are approximately15μm and1μm, respectively.To sum up, two kinds of hollow spheres of aluminum phosphate and iron phosphate can be synthesized with PS microspheres or emulsified paraffin microspheres as the template. When PS microspheres was used as template, the small and uniform size aluminum phosphate and iron phosphate hollow particles can be obtained; While emulsified paraffin microspheres was used as template, the prepared aluminum phosphate hollow particles are large size and non-uniform.