在添加1,1-二苯基乙烯(DPE)的情况下,采用乳液聚合的方法,以过硫酸钾(KPS)作为引发剂,首先以甲基丙烯酸甲酯(MMA)作为第-单体,进行可控“/ 活性”自由基聚合,制备出PMMA-DPE 大分子前驱体,然后再以苯乙烯(St)为第二单体制备PMMA-b-PS 嵌段共聚物. 通过1H-NMR、GPC 等方法对PMMA 前驱体和PMMA-b-PS 嵌段共聚物的结构和分子质量进行了表征,结果证明了其可控“/ 活性”聚合特征. 用扫描电子显微镜(SEM)表征了PMMA-b-PS 两嵌段共聚物在选择性溶剂丙酮/四氢呋喃中的自组装行为.研究结果表明:形成了以PS为基底、PMMA 自组装成均匀排布的点阵,刻蚀掉PMMA 段后可形成高密度、小孔径、均匀分布的纳米蚀孔阵列,蚀孔的直径为80 nm,间距为200 nm 左右. 研究了高温退火与丙酮溶剂熏蒸对有序阵列的影响,结果表明溶剂熏蒸使嵌段共聚物处在过饱和蒸汽压下,抑制了各相的扩散速度和自组装速度,有利于形成较小且均匀的纳米蚀孔.
Synthesis of poly (methyl methacrylate)-b-polystyrene (PMMA-b-PS) with potassium persulfate (KPS) as an initiator was carried out in emulsion polymerization, using a novel chain transfer active 1,1-diphenylethylene (DPE). First the precursor PMMA-DPE latex was prepared by using the controlled/living free radical emulsion polymerization, then the second monomer was swelled into the latex, last, the block copolymer was prepared. The structures and molecular weight of the PMMA-DPE and PMMA-b-PS were characterized by 1HNMR and GPC. The results showed that the PMMA-b-PS was successfully synthesized, and the polymerization could be controlled. Then the effect of solvent or high temperature annealing on block copolymer membrane self-assembly was studied by the scanning electron microscope (SEM). The results manifested that the morphology of the copolymer presents nanodot array. After etching the PMMA segment, the morphology of the copolymer presents nanoporous array with PS as substratum. The diameter of the nanoporous was 80 nm and its pitch was about 200 nm. Solvent annealing is a better method to form small and uniform nanoporous, because of the copolymer in a supersaturated vapor pressure condition.