Synthesis Acrylonitrile Copolymers And PAN-based Membranes Preparation

Preparation of functional membranes and antifouling membranes are two important research subjects. In this thesis, thermo-responsive polyacrylonitrile (PAN) membranes and antifouling PAN membranes were prepared by the immersion precipitation phase inversion process using poly(acrylonitrile-graft-isopropylacrylamide) [P(AN-g-NIPAAm)] as the additive and poly(acrylonitrile-copolymeriation-allyl hydroxy sulfonate betaine) [P(AN-co-AHSB)]. The synthesis of acrylonitrile based polymers reaction conditions, structure and properties were investigated. The casting solution,morphologies and properties of modification membranes were also discussed. The thesis specific rearch are concentrated on the following aspects:NIPAAm polymer with terminal amino group was first synthesized by 2-aminoethanethiol hydrochloride as chain transfer agent. It was then reacted with methacryloyl chloride thus NIPAAm macromer ended with double bond was obtained. The AN-g-NIPAAm copolymer was synthesized from acrylonitrile (AN) and NIPAAm macromer.In addition, P(AN-g-NIPAAm) was also synthesized by a facile approach based on the combination of reversible addition-fragmentation chain transfer and thiol-ene click chemistry followed by radical copolymerization. The graft copolymer was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. Its side chains thermo-responsibility was determined by ultraviolet analysis and water contact angle measurement. Molecular weight and chemical structure analysis were indicated that the content of chain transfer agent could controll the NIPAAm chains length. Turbidity testing was showed that the much longer NIPAAm chains meaned that the lower low critical solution temperature (LCST).Thermo-responsive PAN membranes were prepared by the immersion precipitation phase inversion process using P(AN-g-NIPAAm) as an additive. Effects of P(AN-g-NIPAAm) addition on the morphologies of PAN membranes were investigated by scanning electron microscope(SEM). PAN/P(AN-g-NIPAAm) blending membranes exhibited a typical asymmetrical structure consisting of a dense top layer and a finger-like porous sub-layer. Addition of P(AN-g-NIPAAm) resulted in higher surface porosity and larger pore size. Macrovoids were also gradually suppressed and sponge-like structure became more pronounced. Water flux of the prepared membranes at 40℃, above the LCST of PNIPAAm, is higher than that at 25℃, below the LCST, due to the NIPAAm chains undergoing a coil-to-globule transition act as gate function.P(AN-co-AHSB) was synthesized by copolymerization of AN and AHSB. AHSB was synthesized by quaternization of 3-chloro-2-hydroxy propane sulfonic acid sodium salt and N,N-dimethylallylamine. The production structure was characterized by FTIR and Elemental Analysis. Antifouling P(AN-co-AHSB) membranes were prepared also by immersion precipitation phase inversion. It was found that the P(AN-co-AHSB) membranes possessed high hydrophilicity and strong resistance to the adsorption of bovine serum albumin and lysozyme. The mainly protein pollutiong was irreversible protein adsorption.