PAA-PMMA交联磁性复合微球的制备与性能研究

Study on properties and preparation of PAA-PMMA magnetic microspheres with crosslinking structures

通过滴加氨水控制Fe(Ⅱ)与Fe(Ⅲ)盐混合溶液的pH值,经共沉淀法制得了Fe3O4纳米颗粒,其平均粒径约为13nm。进而用一定量的油酸钠对其原位改性,得到了表面呈疏水性的油基Fe3O4纳米颗粒。在Fe3O4纳米颗粒和二乙烯苯(DVB)存在下,以聚乙烯吡咯烷酮(PVP)为稳定剂,乙醇/水的混合体系为反应介质,由偶氮二异丁腈(AIBN)引发甲基丙烯酸甲酯(MMA)和丙烯酸(AA)进行分散共聚,制得了PAA-PMMA交联型磁性复合微球,核内富含Fe3O4纳米颗粒,其含量可分别调整在42%~71%(质量分数)之间,改变聚合反应条件可将复合微球的粒径控制在100nm^2μm的范围内。研究发现Fe3O4纳米颗粒被PAA-PMMA包覆后,可明显延长其在盐酸中的稳定性。在外加磁场作用下该复合微球能实现快速的分离。

Magnetic nanoparticles were synthesized by in-situ precipitation method through dropwise adding aqueous solution of ammonia to mixed solution of Fe （ Ⅱ ） and Fe （ Ⅲ ） salts. The average diameter of the magnetic nanoparticles is 13nm based on the observation of transmission electron microscopy. The surface of Fe3O4 nanoparticles was modified by using a certain amount of sodium oleate under in-situ processing, to obtain hydrophobic surface of the oil-based Fe3O4 nanoparticles. Crosslinked magnetic composite microspheres with poly （crylic acid）-co-poly（methyl methacrylate） （PAA-PMMA） as shell and Fe3O4 as core were obtained by dispersion copolymerization initiated with 2,2＇-azobisisobutyronitrile （AIBN） in ethanol/water mixed solvent containing poly （vinylpyrrolidone） （PVP） as stabilizer in the presence of Fe3O4 nanoparticles and divinylbenzene （DVB）. The crosslinked microspheres contained 42wt%-71wt% of Fe3O4 through TGA analysis. The average size of the microspheres can be controlled in the range of 100nm-2μm by changing the polymerization conditions. It was found that the stability of the Fe3O4 nanoparticles was prolonged in HCl solution when it packed with PAA-PMMA. The magnetic composite microspheres were separated quickly under the external magnetic field.