Effect of the composition of the copolymer of carboxybetaine and n-butylmethacrylate on low-fouling property of dynamically formed membrane

Abstract

The effect of the composition of the copolymer of 1-carboxy-N,N-dimethyl-N-(2-methacryloyloxyethyl) methanaminium inner salt (CMB) and n-butylmethacrylate (BMA) (poly(CMB-co-BMA)) as a surface modification polymer on the low-fouling properties of dynamically formed membranes was systematically investigated, and the optimum composition for this method was found to be 35:65 [mol:mol], which was prepared from the monomer solution containing 50:50 [mol:mol] of CMB:BMA in the feed (CMB50). This optimized dynamically formed membrane exhibited excellent low-fouling property against both hydrophilic protein and hydrophobic protein. To discuss the reason for this low-fouling property, the hydration states of the polyCMB–water and CMB50–water systems were measured using DSC. The results showed that the water structure in the polyCMB–water system is very similar to that in the poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC)–water system, which is one of the best-known zwitterionic polymers used for biomaterials, and that the water structure in the CMB50–water system has much in common with that in the polyCMB–water system. These water structures are one of the reasons for this system’s low-fouling properties.