RART Controlled Polymerization Polyelectrolyte And Inorganic Porous Material Composite Building A PH-Responsive Ion Transmission Channel

The development of efficient controllable ion transmission channel play a significant role in promoting membrane separation, drug delivery, new energy materials and other fields. An efficient controllable ion transmission channel which means specific ions or molecules can be identified, captured and controlled transferred in response to external environmental conditions in micron-nano-scale, is a hot spot in research. Currently the most discussed of the researchs to build the ion transfer channel is grafting polyelectrolyte to surface of pores of the porous film. Reversible addition-fragmentation chain transfer (RAFT) polymerization was widely used in polyelectrolyte synthesis, as possessing mild reaction conditions, monomer wide applicability.In this paper, RAFT polymerization polyelectrolytes were grafted to the surface of pores of the anodic aluminum oxide (AAO). The response of the ionic conductivity of composite membrane to the pH was investigated.(1) Synthesis of polyelectrolytes.(4-cyanopentanoic acid)-4-dithiobenzoate was firstly synthsized, which was then used in controlled synthesis of methacrylic acid (MAA),2-(diethylamino) ethyl methacrylate (DEAEMA) and2-acrylamido-2-methyl-l-propanesulfonic acid (AMPS) via RAFT polymerization with4,4’-azobis(4-cyano valeric acid) as initiator. Adjusting [monomer]0:[CTA]0ratios, three different degree of polymerization polyelctrolytes were obtained. The polymerizations exhibited the characteristics of a controlled/"living"polymerization which demonstrated well controlled molecular weight and low molecular weight distribution.(2) Fabrication of pH-responsive ion channels with PMAA/AAO composite. AAO membrane was chosed as the matrix for the ion transfer channel. The AAO membranes were firstly plasma treated and APTES modified. Using "Graft to" method, PMAA polyelectrolyte was grafted to the AAO membrane channels, having a pH responsive AAO-g-PMAA composite membrane. The influence of pore size and the PMAA solution concentration to grafting effect was investigated by TGA, FTIR, SEM analyzing. Sepcial emphasis was put on the influence of pore size and the PMAA solution concentration to pH-responsive performance using AC impedence. The results showed that the AAO-g-PMAA composite, which was obtained by immersing the25nm AAO menbrane in10wt%PMAA solution, has good pH-responsive performance. The AAO-g-PMAA composite, which was obtained by immersing the75nm AAO menbrane in15wt%PMAA solution, has a certain pH-responsive performance. The AAO-g-PMAA composite, which was obtained by immersing the100nm AAO menbrane in PMAA solution, was only weakly pH-responsive.