그라프트 공중합을 이용한 비수용성 메틸셀룰로오스의 합성 및 막응용

Abstract

The development of novel polymer materials with high functionality has received attention in recent decades. Among the natural polymers, cellulose and its derivatives are widely used, because they are inexpensive, most abundant, biodegradable and renewable. Methyl cellulose (MC) is a highly functional cellulose derivative with properties such as being non-ionic and having pH stability, hydrophilicity and high water retention. But since MC is water soluble, some applications are limited, for example, use as a water treatment membrane. Therefore, in this study, high functional MC-based graft copolymers were prepared by the reaction of redox system polymerization with ceric ion initiation. In order to graft the water insoluble copolymer with a soluble organic solvent, water soluble MC as a main backbone was used by changing the molar ratio of the grafted vinyl monomer without the destruction of the inherent MC properties. The various vinyl monomers such as, acrylonitrile (AN), methyl methacrylate (MMA) and styrene (ST) were grafted onto the MC backbone by ceric (IV) ion- initiated free radical polymerization in aqueous medium. Ceric (IV) ion-initiated polymerization was a useful method to obtain high molecular weight molecules. The reaction was homogeneous and the grafting percentage (%G) could be easily be controlled. The hydrophilicity, thermal stability, molecular weight, zeta-charge and mechanical strengthe were investigated using Fourier transform-infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA), gel chromatography (GPC), zeta-potential, water contact angle and universal testing machine (UTM), respectively. The produced graft copolymers showed an improvement in thermal stability and hydrophilicity, maintaining the properties of MC. In addition these graft copolymers could be applied for antifouling water-treatment membranes. The feasibility of these copolymers as water-treatment membranes was investigated by flux, rejection and antifouling test using a dead-end filtration system. The prepared copolymer membranes showed different properties, varying by the grafted monomer. The AN graft copolymer represented remarkable antifouling properties compared with the two other grafted copolymers.