Synthesis,Structure Characterization Of Polypropylene Membrane Surfacr Grafting Modification By In-situ Chlorinating Copolymerization And Its Environmental Response

In this study,a novel chemical surface modification method of polyolefin membranes is applied following the in-situ chlorinating graft copolymerization(ISCGC).Polypropylene(PP)/methyl methacrylate(MMA)system was used as an example.A unique structure was formed by the modification process on the original membrane surface and the product exhibited an environmental response.In ISCGC,chlorine is decomposed into free radicals under ultraviolet(UV)or heat and initiates the formation of macromolecular radicals,which simultaneously facilitates the latter grafting reaction and terminates the reaction process constantly.The special reaction process gives the product a special molecular structure: In the process of reaction,the high activity of the chlorine radical causes the whole molecular chain to have enough grafting active sites,and the grafting density of the framework polymer is high;at the same time,chlorine molecules are also involved in the termination reaction,so that the growing side group is terminated by a high concentration of chlorine molecules,and the rapid termination of the molecule leads to a small molecular weight and narrow distribution,which is close to 1;based on the termination of the transfer of chlorine molecules,the end of the product contains chlorine substituents,so the product is a multifunctional polymer.The process is similar to ?grafting from?.The main content of this paper is to study the process and structure of the ISCGC process to prepare the polymer membrane with high grafting degree and uniform surface grafting effect.First of all,in order to improve the grafting effect,the PP/MMA system was used to explore the factors affecting the grafting rate,and the reaction conditions were optimized.The main control,including the effects of chlorine flow matrix in the monomer infiltration time,reaction time,reaction temperature and pre chlorination on the grafting degree and surface uniformity.Secondly,the structure of the grafted CPP-cg-MMA membrane was characterized in detail including the product surface molecular structure,thickness,coverage and morphology structure,characterization methods of total reflection infrared spectroscopy and 1H-NMR analysis,molecular weight and molecular weight distribution,scanning electron microscopy,laser confocal microscopy and atomic force microscopy analysis.Finally,the environmental response of MMA,AA,and AM monomers grafted onto the surface of PP membrane was investigated.The contact angle of the modified PP membrane on the wettability of water after treatment with different solvents,the affinity of the solvent and the wettability of the water under different pH were measured in three aspects.