Triblock Terpolymers Bearing a Redox-Cleavable Junction and a Photo-Cross-Linkable Block

Abstract

Two linear triblock terpolymers were synthesized and used to coat cotton textiles. These copolymers consist in sequence of a water-soluble poly(ethylene glycol) (PEG) block, a highly water- and oil-repellant poly[2-(perfluorooctyl)ethyl methacrylate] (PFOEMA) block, and a photo-cross-linkable poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) block. The PEG block bonds to PFOEMA via a redox-cleavable disulfide junction (-S2-). To prepare the copolymers, monomethoxy PEG (PEG-OH) was derivatized to yield a PEG chain bearing one terminal thiol group (PEG-SH). Atom transfer radical polymerization and deprotection chemistry were used to prepare Py-S2-PFOEMA-b-PHEMA, where PHEMA and Py-S2- denote poly(2-hydroxyethyl methacrylate) and a terminal pyridin-2-yldisulfanyl group, respectively. Reacting PEG-SH with Py-S2-PFOEMA-b-PHEMA via a thiol–disulfide exchange reaction yielded PEG-S2-PFOEMA-b-PHEMA, and the cinnamation of the PHEMA block produced PEG-S2-PFOEMA-b-PCEMA. PEG-S2-PFOEMA-b-PCEMA dispersed in water and plasticized by a trace amount of dimethyl phthalate was then used to coat cotton textiles, and this coating was secured by photo-cross-linking the PCEMA domains. Treating the coating with dithiothreitol cleft the disulfide junction and thus the PEG block, revealing the hidden PFOEMA block and its water- and oil-repellant properties. Aqueous solutions of these copolymers could thus be applied onto a substrate to provide amphiphobic coatings.