Synthesis And Characterization Of Thermo-sensitive Polymer And Its Applications In Functional Membranes

Temperature sensitive polymer P(N-isopropyl acrylamide) (PNIPAAm) in aqueous solution has a lower critical solution temperature (LCST).In this work,two new temperature-sensitive polymers, P(Tetrahydrofurfulylacrylamide)(PTHFAA) and P(Tetrahydrofurfulylmethacraylamide)(PTHFMA) were synthesized, which are more hydrophilic and have higher lower critical solution temperature than PNIPAAm.THFAA or THFMA were also copolymerized with N-isopropyl Acrylamide by radical copolymerization for the preparation of the copolymers,respectively.The effect of composition of the copolymer on the lower critical solution temperature(LCST) were invertigated.The results showed that,by changing the mole ratios of monomer in copolymerization,the lower critical solution temperatures of the copolymers could be effectively designed.The copolymers, P(NIPAAm-co-THFAA) and P(NIPAAm-co-THFMA) could be effectitively controlled the lower critical solution temperature,by changing the molar ratios of the monomers.NIPAAm monomer was copolymerized with the electronegativite anion monomer,such as 2-arcylamide-2-methy-1-propanesulfonicacid and acrylic under the preseure of the cross-linker N N-methylenebisacrylamide via emulsion polymerization.The microgel produced by the copolymerization had both temperature-sensitivity,PH-sensitivity. Through electrostatic self-assembled with aniline,the microgelpolyaniline composite microspheres sensitived to temperature,PH and responsived to proton acid just in the same way with polyaniline.Pore-filling N-isopropylacrylamide(NIPAAM) polymer hydrogels were successfully grafted onto track-etched polycarbonate(PCTE) membranes by plasma-induced graft copolymerization.The microstructure and morphology of the PNIPAAm-g-PCTE membranes was investigated by XPS,SEM,ATR-FTIR,TGA and water flux experiments.The effective pore sizes were regulated by the volume change of the cross-linked PNIPAAm hydrogels at the temperatures around its LCST.The NIPAAm-g-PC membranes demonstrated fast and reversible swelling changes in a narrow temperature range.The on-off water flux ratio become more significantly with the increase of the monomer concentration.The contact angle results showed that the thermal responsive gating characteristics of PNIPAAm-g-PCTE membranes were mainly dependent on the pore size change.On the other hand,with same monomer concentration,the on-off water flux ratio of the cross-linked composite membranes is higher than the linear ones.