Novel Block Copolymers as Nanofiltration Materials

Abstract

The overarching goal of this research was to forge a link between materials science and engineering that may eventually lead to development of new membranes with decreased fouling tendency. Polymer structure influences water transport rates, solute partitioning, and fouling resistance. This article presents the results of testing the first generation of a novel class of nonporous block copolymers for use in nanofiltration (NF) membranes. The block copolymers comprised low surface energy fluoropolymers and highly hydrophilic hydrocarbon-based polymers. The very low surface energy of the fluoropolymer block was intended to resist adhesion of natural organic matter (NOM), a common foulant in drinking water applications of nanofiltration technology. The hydrophilic block was intended to provide channels for water permeation. Thin-film composite membrane tests with a coagulated, settled, and cartridge-filtered drinking water sample showed that the experimental membrane produced comparable water flux to a commercial NF membrane. However, flux decline was also similar to that of the commercial NF membrane. Despite the failure to resist fouling, the data suggest that NOM may be more easily removed from the experimental membrane surface than the commercial membrane surface. Dense film testing of the experimental materials provided measurements of NOM partitioning and diffusion.