亲/疏水不对称空心聚合物微球制备及磁性粒子装载研究

PREPARATION OF HOLLOW POLYMER MICROSPHERES WITH HYDROPHILIC/HYDROPHOBIC ASYMMETRIC SURFACE AND LOADING OF MAGNETIC NANO-PARTICLES

首先将(马来酸酐-醋酸乙烯酯共聚物)核/(马来酸酐-二乙烯基苯共聚物)壳微球的壳层外表面酐基烷基溴化,然后将核溶蚀、壳层内表面酐基水解,制得内表面含亲水羧基、外表面含烷基溴、具有微孔(Barrett-Joyner-Halenda平均孔径14.9 nm)的空心聚合物微球.以此空心微球为微反应器,使Fe2+和Fe3+通过球壁微孔渗入空心球并被内表面羧基吸附,而空心球外表面铁离子不被烷基溴吸附,可冲洗除去;然后,在碱性条件下,使Fe2+和Fe3+共沉淀生成磁性粒子,从而实现了磁性粒子在空心球内部的成核、增长和装载.进一步考察了反应配比、温度和时间等参数对复合磁性微球磁化强度的影响.Fe2+和Fe3+的摩尔比为2/3,反应温度为80℃,反应1.5 h时,空心聚合物微球装载磁性粒子的效果和装载后复合微球的磁性能最佳,饱和磁化强度可达12.34 emu/g.

As a microreactor,hollow microspheres could be used to load magnetic nanoparticles.Asymmetric hollow polymeric microspheres with micropores of 14.9 nm,alkyl bromine groups on exterior wall and carboxyl groups on interior wall were produced through three steps：（a） synthesis of the core-shell microparticles with copolymer of maleic anhydride（MAn） and divinyl benzene（DVB） as the shell,and copolymer of maleic anhydride（MAn） and vinylacetate（VAc） as the core;（b） surface bromizing of the core-shell microparticles by reaction with dibromoethane;（c） etching of the cores with acetone,and followed by the hydrolyzing of the anhydride groups on interior wall.Fe3O4 magnetic nanoparticles were loaded into the cavity of prepared hollow polymeric microspheres by two steps： first,Fe2＋ and Fe3＋ were infiltrated into the hollow microspheres and selective adsorbed on the interior wall under the effect of carboxyl groups;secondly,in appropriate condition,coprecipitation were carried out to obtain Fe3O4 magnetic nanoparticles.In addition,influences of parameters relating to the above mentioned reaction,such as the mole ratio of Fe2＋ and Fe3＋,reaction temperature and reaction time,on the saturation magnetization of the magnetic microspheres were investigated.The results show that,the optimum reaction conditions to the balance of loading selectivity and value of saturation magnetization were as follow： molar ratio of Fe2＋ and Fe3＋ was 2/3,reaction temperature was 80℃ and reaction time was 1.5 h,for obtained the best value of saturation magnetization 12.34 emu/g.