Synthesis of well-defined responsive membranes with fixable solvent responsiveness

A versatile method is described to synthesize a new family of solvent-responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2-bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track-etched membrane followed by room-temperature ATRP grafting of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) (P(HEMA-co-DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo-crosslinkable PET-g-PHEMA/CA membrane and PET-g-P(HEMA/CA-co-DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA-co-DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. (c) 2014 Society of Chemical Industry