静电组装法在SiO_2表面构筑高分子刷的合成及表征

以对2-溴异丁酸-2′-(对磺苯基)乙酯为引发剂引发苯乙烯发生原子转移自由基聚合,得到的聚合物与NaOH反应转化为端基为磺酸钠的PS(PS-SO3Na).然后采用静电组装方法将PS-SO3Na与表面正离子化的SiO2胶体(SiO2-CBAFS)进行静电组装,得到表面构筑了高分子刷的SiO2胶体/粉体.采用IR、1H-NMR、TG、TEM、AFM、GPC和表面水接触角对组装体系进行结构表征、组装量和部分组装规律研究.结果表明,采用对2-溴异丁酸2′-(对磺苯基)乙酯为引发剂可以制备完全端磺酸基的PS-SO3Na,并且采用静电组装法在SiO2颗粒表面可构筑组装量高达34.4%的高分子刷,有效的提高了高分子刷的组装量;TEM观察下在SiO2胶体颗粒外围可见白色晕圈,PS-SO3Na刷的存在明显改善了SiO2胶体颗粒的分散状态;当样品润洗溶剂由THF变换为H2O时,自组装单层膜的表面水接触角下降幅度小于4°;综合TG、AFM和表面水接触的测试结果发现,用于组装的PS-SO3Na分子量介于1.5×104～3.6×104时,溶液浓度介于2.5×10-5～5×10-5mol/L时,SiO2颗粒具有较好的表面修饰效果.

SYNTHESIS AND CHARACTERIZATION OF POLYMER BRUSHES CONSTRUCTED ON SiO2 SURFACES BY ELECTROSTATIC-ASSEMBLY

Sodium sulfonate terminated polystyrene (PS-SO3Na) was synthesized by atom transfer radical polymerization of styrene with 2′-(p-sulfophenyl)ethyl 2-bromoisobutyrate ao initiator,and the resulting polymer reacted with NaOH.The initiator was lyntheaized from 2-phenylethanol and 2-bromoisobutyryl bromide.Polymer brushes constructed on the surface of cationically functionalized SiO2 (SiO2-CBAFS) were prepared via electrostatic-assembly between PS-SO3Na and SiO2-CBAFS.IR,1H-NMR,TG,TEM,AFM,GPC and water contact angle were used to characterize the structure,the assembly amount and the regularity of the assembly system.The results show that PS-SO3Na can be synthesized with 2′-(p-sulfophenyl)ethyl 2bromoisobutyrate successfully,the assembly efficiency is increased in some extent with the polymer terminated 100% sodium sulfonate,and the amount of polymer brushes assembled on the surface of SiO2 is as high as 34.4% ;white layers can be observed at the surface of SiO2 colloid particles with TEM,and the dispersion of SiO2 is modified obviously;the descent of water contact angles of the samples below 4° when the rinsed solvents altered from THF to H2O;the decorate effect of SiO2 is preferable when the molecular weight of PSSO3Na range from 1.5 × 104 to 3.6 × 104 and the molar concentration of polymer solutions range from 2.5 × 10-5mol/L to 5 × 10-5mol/L with the analysis of the results of TG,AFM and water contact angles.