Surface modification by self-assembled coating with amphiphilic comb-shaped block copolymers: A solution to the trade-off among solubility, adsorption and coating stability

Abstract

Surface coating with amphiphilic block copolymers containing a long hydrophobic anchor block in polar solvent often suffered from the damaging impact of micelles, often leading to a significant decrease in adsorption amount and packing density. In this study, a series of amphiphilic comb-shape block copolymers, poly[poly(ethylene glycol) methyl ether acrylate]-b-poly(styrene-co-N,N-dimethylacrylamide) (P(PEGMEA)-b-P(St-DMA)) were synthesized successfully by reversible addition-fragmentation chain transfer (RAFT) polymerization with fluorescencelabelled RAFT agent. The chain structure and chemical composition of copolymers were characterized by 1H NMR, FTIR and GPC. The surface self-assembled coating through physical adsorption of P(PEGMEA)-b-P(St-DMA) in ethanol on the surface of polyacrylonitrile (PAN) membrane was investigated by XPS, ATR-FTIR, SEM and water contact angle measurements. The antifouling properties of the modified membranes were evaluated using BSA as a model protein. It was found that the introduction of appropriate DMA (DMA/St in the range of about 0.1 to 0.2) into the hydrophobic segment can significantly increase the solubility of copolymers and alter their aggregation behaviors, alleviate the impact of micelles, increase adsorbed amount of copolymers, and thus can enhance the hydrophilicity and anti-fouling properties of membranes. Moreover, the stability analysis indicated that P(PEGMEA)-b-P(St-DMA) with appropriate DMA in the hydrophobic anchor block can form a relatively stable coating on the surface of PAN membrane. Consequently, the adjustment of the structure and composition of anchor segment may be a potential solution to the trade-off among solubility, adsorption amount and coating stability when amphiphilic block copolymers were used to surface modification by self-assembled coatings. Open image in new window