Morphology and permeability of membranes of polysulfone-graft-poly(tert-butyl acrylate) and derivatives

Polysulfone-graft-poly(tert-butyl acrylate) (PSf-g-PtBA) membranes with PtBA weight fraction ranging from 19.7% to 34% were prepared from the mixing at different ratios of two PSf-g-PtBA samples, which have approximately one PtBA branch per PSf chain but different PtBA chain lengths. PSf-g-PAA membranes, where PAA denotes poly(acrylic acid), were prepared either from the in situ hydrolysis of PtBA in pre-formed PSf-g-PtBA membranes or from casting solutions of PSf-g-PAA. Neutralization of PAA with tetraalkylammonium hydroxide yields PSf-g-P(AA-TAA), where P(AA-TAA) denotes poly(tetraalkylammonium acrylate). Casting solutions of PSf-g-P(AA-TAA) yielded PSf-g-P(AA-TAA) membranes. This paper investigates the variation in the permeability of water and 2-chloroethyl ethyl sulfide (CEES) vapor across the membranes as a function the weight fraction of PtBA, PAA, or P(AA-TAA), where CEES is used as a simulant for the chemical warfare agent sulfur mustard bis(2-chloroethyl) sulfide. Also presented are the TEM images of thin sections of the different membranes revealing the morphology of the PtBA, PAA, and P(AA-TAA) domains.