pH-dependent property of carboxyl-based ultrafiltration membranes fabricated from poly(vinyl chloride-r-acrylic acid): pH-dependent property of carboxyl-based ultrafiltration membranes fabricated from poly(vinyl chloride-r-acrylic acid)

Carboxyl groups in the membranes usually contribute the hydrophilicity and antifouling properties. However, membrane performance including permeation and separation properties is not stable at different pH environments due to pH sensitivity of carboxyl groups. In this work, a series of membranes from random copolymers poly(vinyl chloride-r-acrylic acid) [P(VC-r-AA)] were fabricated via nonsolvent induced phase separation process. The morphology and surface properties were investigated. The pH-dependent property of carboxyl groups contained ultrafiltration membranes were studied in detail. The results indicated that pH sensitivity of these membrane was restrained, which was mainly attributed to the random sequential structure of VC and AA repeating unit in P(VC-r-AA) copolymer. The probable arched structures on the pore surface/wall at alkaline environment limited the obvious change of the pore size, which resulted in the stable permeation and separation properties at the varied pH environments. Therefore, it indicated that P(VC-r-AA) was a kind of promising membrane material which would be widely applied in water treatment field. (c) 2018 Wiley Periodicals, Inc.