Synthesis And Characterization Of Fe₃O₄@ SiO₂ Magnetic Composite Particles

Environmental responsable materials change their physicochemical properties with surrounding environmental.They play an important role in separation and purification, drug controlled release and catalysis. The temperature-sensitive magnetic nano particles were prepared from ethynyl-terminated poly(vinylcaprolact am) (PNVCL-=) and azido-terminated Fe3O4@SiO2(Fe3O4@SiO2-N3)nano particles, which are abtained from the modification of Fe3O4@SiO2 nano particles, and their structures and characters were studied. The details are as follows.1.Fe3O4 nano particles were prepared by coprecipitation, then cover by sol-gel method and modified by silane coupling reagent 3-Glycidyloxy propyltrimethoxysil-ane to get Fe3O4@SiO2-N3. Their structures were characterized by FT-IR, XRD, TEM, DLS and VSM. TEM showed that Fe3O4@SiO2-N3 particles have uniform core-shell structures with average particle diameter about 75nm. DLS indicated the average diameter is 78.2nm. the magnetic Fe3O4@SiO2-N3 nano particles demonst rated good super-paramagnetism with saturated magnetization 25.43emu/g in VSM.2. PNVCL-≡was prepared by free radical polymerization and esterification reaction. Temperature-sensitive magnetic composite particles Fe3O4@SiO2-PNVCL was synthesized by click reaction between Fe3O4@SiO2-N3 and PNVCL-≡and Characterized by FT-IR,1H NMR, GPC, TEM, XRD, DLS, VSM and UV. TEM showed that the magnetic Fe3O4@SiO2-PNVCL nano particles were sphere with good dispersibilities. Their average diameters are about respectively 87nm,98nm. DLS indicated the LCST of Fe3O4@SiO2-PNVCL decreased with the length of the PNVCL segment. Observed by VSM, Fe3O4@SiO2-PNVCL showed good super-paramagnetism with saturation magnetizations 8.48emu/g and 7.45emu/g resp-ectively, which reach the index of magnetic separation.3. The adsorption of Bovine Serum Albumin by Fe3O4@SiO2-PNVCL was studied by UV/VIS spectroscopy and factors that affected adsorption quantity were discussed.The maximum adsorption amount(79.85mg/g) appears in pH=6.0, adsorption time(120min) and temperature(35℃),The desorption quantity of BSA was 70.12mg/g and the desption rate was 87.81% when the pH was 9.0 and the temperature was 25℃.