反相微乳液中纳米 SiO2粒子的合成及其杂化膜的制备和性能表征∗

摘要

在以两亲性三嵌段大分子聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO,F127)为表面活性剂、甲基丙烯酸甲酯(MMA)为油相介质、正硅酸乙酯(TEOS)为前驱体、氨水为水解催化剂的反相微乳液中合成纳米 SiO 2粒子,进而采用微乳液原位聚合法制备 SiO 2/PMMA 有机-无机杂化膜.利用紫外可见光谱和透射电镜分析反相微乳液中纳米 SiO 2粒子的形成与形貌.通过聚合过程中体系粘度的变化探讨纳米SiO 2粒子对成膜过程的影响.采用扫描电镜表征了SiO 2/PMMA 杂化膜的结构,结合气体渗透实验考察杂化膜的 CO 2/N2分离性能.结果表明,在反相微乳液体系中增加 TEOS 的投加量,有利于更多纳米 SiO 2粒子的形成,但对原位聚合成膜过程的抑制作用增强.由于两亲性大分子 F127的保护作用,原位聚合成膜后纳米 SiO 2粒子较均匀地分散在杂化膜中.杂化膜的CO 2、N2渗透性及 CO 2/N2渗透选择性表现出随TEOS 投加量的增加先增大后减小的趋势,当 TEOS投加量为4．0 mL 时,制备的 SiO 2/PMMA 杂化膜的CO 2渗透系数为1．64×105 Barrer,CO 2/N2渗透选择性可达27．31.%SiO 2 nanoparticles were firstly synthesized in a reverse microemulsion using triblock copolymer PEO-PPO-PEO (F127)as the surfactant,methyl methacrylate (MMA)as the oil phase,and NH 3 •H 2 O solution as the hydrolysis catalyst,after TEOS was added to the microemulsion as the precursor of SiO 2 .Then,SiO 2/PM-MA inorganic-organic hybrid membranes were successfully fabricated by in-situ microemulsion polymerization. The formation and the morphology of SiO 2 nanoparticles in reverse microemulsion were analyzed via UV-Vis absorption spectroscopy and Transmission Electron Microscopy.The effect of SiO 2 nanoparticles on the poly-merization of MMA was explored by measuring the change in the viscosity of solution during polymerization. Scanning electron microscopy was employed to characterize the morphology and surface properties of hybrid membranes.The separation performance of these novel hybrid membranes was evaluated by gas permeation ex-periments.The results showed that more SiO 2 nanoparticles with small size generated in the reverse microemul-sion.Due to the protection of surfactant on the particles during the polymerization,SiO 2 nanoparticles distribu-ted homogeneously in the membranes,which improved significantly the performance of hybrid membranes for CO 2 separation.Both the gas permeability and separation performance of the hybrid membranes first increased and then decreased with SiO 2 content.When the TEOS was 4.0 mL,the CO 2 permeability of hybrid membrane was 1.64×10 5 Pa,CO 2/N2 permeation selectivity can reach 27.31.