Organic-inorganic Hybrid On Polypropylene Membrane Surface And Its Properties

Organic-inorganic hybrid ultrafiltration membrane has excellent physical and chemical stability, more complete membrane pore structure, better membrane permeation and separation performance and good anti-fouling ability; it becomes one of the research hotspots in recent years. Polypropylene membrane has good chemical stability, heat, acid and alkali, high mechanical strength, low price, etc., so it gives people widespread concern and has wide applications. However, the strong hydrophobic Polypropylene can easily be contaminated in the separation process, so that the capacity of separation decreased, costs increased, and modifying hydrophilic materials on the membrane is an effective way to solve the membrane fouling. By the reversible Addition-Fragmentation chain Transfer method and UV irradiation for the living polymerization, can make polypropylene membrane surface graft hydrophilic substances, reaching the purpose of polypropylene membrane modification, besides, in order to degrade some organic matters in the sewage treatment and achieve sterilization, on the grafting of Polypropylene modified by hydrophilic acrylic acid, by organric-inorganic hybrid, assembling nano-TiO₂, in order to achieve the purpose of modification. This paper aims to RAFT polymerization by UV irradiation to graft hydrophilic material onto the polypropylene membrane surface, and organic-inorganic on the membrane surface, changing the polypropylene membrane of a number of deficiencies, to expand its scope of applications.This thesis research content and results are as follows:1. Select benzyl dithiobenzoate as chain transfer agents, by the reversible addition-fragmentation chain transfer approach and the ultraviolet radiation, result in polypropylene microporous membrane (PPMM) functional modification. Prepared PPMM-PHEMA-PNIPAAm membrane were investigated irradiation time, the concentration of chain transfer agent influencing on graft reaction to light, and Attenuated total reflection- Fourier transform infrared spectroscopy(ATR-FTIR), X-ray Photoelectron Spectroscopy(XPS) were characterized. By ATR / FI-IR and XPS show that poly 2-hydroxy ethylmethacrylate and polyN-isopropylacrylamide were grafted onto polypropylene membrane. With the irradiation time increased and decreased the concentration of chain transfer agent, graft chain length increased linearly. Add 0.1-0.02mmol/L benzyl dithiobenzoate(BDTB), with the irradiation time, and graft yield increased linearly, but compare the addition of BDTB with no BDTB, the grafting yield decreased significantly. PP-PHEMA graft copolyner as an active base for a further grafting N-isopropylacrylamide forms of PP-g-PHEMA-b-PNIPAAm as a block polymer.2. Through RAFT method grafting organic matter onto membrane surface, then by organic-inorganic interaction between the film formed on the membrane surface and inorganic layer, thus the inorganic layers adsorb onto the membrane surface, achieving the purpose of preventing pollution. first, PP microporous membrane grafted acrylic acid (AAc), through the coordination role on the membrane surface, the introduction of titanium dioxide nano-particles, in the UV irradiation, it can degrade some of organic matters, studies have shown that the high rate of acrylic acid grafting, and titanium oxide surface adsorption (TiO₂) has stronger capacity, this experimental degradation of 25 mg/L of phenol by organic-inorganic hybrid membranes, degradation effect is there, but obviously not enough.