【作者】 曹康丽；

【导师】 史铁钧；

【作者基本信息】 合肥工业大学 ， 材料学， 2006， 硕士

【摘要】 本论文采用分散聚合方法成功的制备出单分散聚丙烯酰胺（PAM）微球,以及以单分散二氧化硅（SiO₂）微球为核、聚丙烯酰胺（PAM）为壳的SiO₂/PAM核壳复合微球。 在乙酸乙酯/乙醇的混合溶液中,采用聚乙烯基吡咯烷酮（PVP）为分散剂,偶氮二异丁腈（AIBN）为引发剂,通过分散聚合法制备出单分散亚微米级的PAM微球。研究了聚合参数诸如:混合溶剂比例、分散剂浓度、初始单体浓度和引发剂浓度对聚合体系的稳定性、微球粒径及其分布、转化率、产物分子量的影响和变化规律。研究发现,分散聚合体系中吸附稳定机理和接枝稳定机理同时存在,后者为主;乙酸乙酯/乙醇体积比在5∶5～7∶3范围之间,可得到粒径在200nm左右且分布较窄的PAM微球;PAM微球的粒径随分散剂浓度的增大而减小,随引发剂浓度的增加而增大,且初始单体浓度较高或较低,都得不到单分散性微球;在反应初期就发生了自动加速现象,由于凝胶效应分子量随转化率的增大而增加;单体转化率随分散剂浓度、初始单体浓度及引发剂浓度的增加而增大,乙酸乙酯/乙醇体积比在7∶3时,高达99.7%;产物分子量随乙酸乙酯体积含量、初始单体浓度和分散剂浓度的增加而增大,随引发剂浓度的增加而下降,但是分散剂用量过多也会导致其减小。 采用分散聚合成功制备了以单分散SiO₂微球为核、PAM为壳的SiO₂/PAM核壳复合微球。根据St（?）ber方法,制备了单分散SiO₂微球,微球粒径随着TEOS、氨水浓度的增加而增大。采用硅烷偶联剂KH-570对单分散SiO₂微球进行表面处理,得到了g-SiO₂;TEM显示,经表面处理后的SiO₂微球继续保持单分散性,粒径有所增加。以单分散SiO₂微球或g-SiO₂微球为载体粒子,采用分散聚合法在其上包覆AM,借助TEM、IR等检测手段对其进行了表征;研究发现,以g-SiO₂微球为载体粒子能得到核壳结构,这种SiO₂/PAM核壳复合微球的粒径大约为163nm,包覆层30nm左右。更多还原

【Abstract】 Monodisperse PAM microspheres and SiO₂/PAM core/shell composite microspheres composed of SiO₂ core and PAM shell were prepared by dispersion polymerization method respectively.Using PVP as the stabilizer and AIBN as the initiator, monodisperse PAM microspheres sized in submicron were prepared in ethyl acetate/ethanol medium by dispersion polymerization method. The influences of polymerization parameters, such as concentration of stabilizer, initiator, monomer and solvent composition, etc. on particle size and size distribution, the conversion efficiency and molecular weight were investigated. Both adsorption and graft stabilization mechanism were concurring in this system and the latter is dominant. The size distribution is narrow when the volume ratio of ethyl acetate and ethanol ranges from 5:5 to 7:3. Paticle size decreases with the increase of the concentrations of stabilizer and the decrease of the concentration of initiator, moreover, monodisperse microspheres cannot be obtained when the concentration of monomer is too high or too low. At early period of dispersion polymerization, auto-accelerate phenomenon was observed, and molecular weight gradually increased with the increase of conversion because of gel effect. Conversion efficiency increased as the concentrations of stabilizer, initiator and monomer increased. Molecular weight increased with the increase of the concentration of ethyl acetate, stabilizer and monomer increase, and the decrease of the concentrations of the initiator, but when the concentration of stabilizer is too high, the molecular weight decreased.SiCVPAM core/shell composite microspheres composed of SiO₂ core and PAM shell were prepared by dispersion polymerization successfully. Firstly, monodisperse SiO₂ particles were synthesized by the Sto|¨ber method, particle sizes increased from when the concentrations of TEOS and ammonia increased. Secondly, g-SiO₂ particles were obtained using coupling agent KH-570 to modify SiO₂ particles. The TEM show that the g-SiO₂ particles were still in monodisperse and the size of particles increased. Finally, the SiO₂ particles and g-SiO₂ particles were encapsulated by dispersion polymerization of AM, and then were investigated by TEM and IR. The results show that the core/shell structure were obtained using g-SiO₂ particles as core, The particle size of core/shell composite microspheres was about 163 nm and the layer of PAM encapsulation was about 30nm.更多还原