Recent advances in SNIPS, a novel method that combines self-assembly of block copolymers with nonsolvent induced phase separation, have led to design a new generation of highly selective ultrafiltration membranes. An important issue in such integral asymmetric membranes is the formation of defect-free selective layer with tailored pore size. Besides the possibility to design molecular architecture for a desired pore size and blending of block copolymers with homopolymers or low molecular additives, blending of two chemically similar block copolymers presents a facial approach to tailor the pore size of isoporous membranes. One particular challenge that will be addressed in this work is to understand more about the influence of block copolymer structure in the casting solution on the membrane formation and controlling pore characteristics of the selective layer and microporous underling support layer. Present work reports a systematic investigation of the correlation between the block copolymer structure in the membrane casting solution and the morphology of the isoporous membrane by varying the solvent system in polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer solutions. Evaluation of the results establishes the key role of the solvent/solvent mixture in the structure formation and self-assembly of block copolymer in the solution and its controlling rule on the surface pore characteristics, ordering and uniformity of the pores, thickness of the selective layer, and porous substructure of the final membrane. Furthermore, the structure formation of the pure and the binary blends of diblock copolymers in different solvents or solvent mixture, and the morphology of the blend films prepared by the slow evaporation of solvent were studied using complementary scattering and microscopy methods. The scaling behavior describing the molecular weight dependence of domain spacing in the blend films will compare from the scaling behavior of the surface structure of the integral asymmetric membranes made from similar blends.

Structure formation of pure and binary blends of block copolymers in solution, in membrane, and in bulk

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.