Simultaneously enhanced separation and antifouling properties by synergistic effect of pore-formation and surface segregation through incorporating bowl-like amphiphiles

Abstract

Herein, we propose a new strategy to improve the separation and antifouling properties of ethylene vinyl alcohol (EVAL) membranes by a dual pore formation mechanism modified with natural macrocyclic amphiphiles cyclodextrin (CDs). The amphiphilic bowl-like geometry of CDs, consisting of a hydrophobic cavity and hydrophilic rim, induces spontaneous surface segregation during the non-solvent induced phase separation to form a CD-enriched layer. Here, CDs play multiple roles, including pore-forming and antifouling enhancement agents, by modifying the morphological, physical, permeation, and separation properties of the membranes. The three-dimensional honeycomb sponge-like structure was determined by SEM analysis, and the elemental composition was examined by SEM-EDX analysis. The O element indicated a gradient decrease distribution from the top to the bottom layer of the cross-section, concomitant with the combination of pore-forming and surface segregation functions. The introduction of amphiphilic CDs increases the roughness, hydrophilicity, and porosity of the membranes. Furthermore, the CDs-modified EVAL (d-M) membranes have excellent mechanical properties, a high water flux (148 L/m2h) with superior rejection to BSA (98%), and can be used for dye separation (Congo Red: 99.7%, Coomassie brilliant blue: 97.5%, Trypan blue: 92.4%). Moreover, the modified EVAL with the best performance has excellent antifouling capacity and long-term stability. This work demonstrates the effect of the addition of CDs and octanol as dual pore formers on the fabrication of hydrophilic antifouling membranes for efficient separation.