Surface Graft Modification of Styrene—Butadiene—Styrene Triblock Copolymer Membrane by Ultraviolet Irradiation

To improve the wettability or hydrophilicity of the styrene— butadiene—styrene (SBS) triblock copolymer membrane using as transdermal patches, a series of graft copolymers were prepared by grafting hydrophilic monomers onto SBS membrane through ultraviolet irradiation technique. The characterization of the grafted membranes and the influence of various grafting factors on grafting percentage were studied. Infrared and X-ray photoelectron spectroscopy techniques were used to elucidate the surface properties of the grafted membrane. Scanning electron microscopy was used to observe the surface morphology of the grafted membrane. Experimental results showed that the grafting percentage and extent of grafting per area (mg/ cm ² ) were about linearly increased with an increase of the molar ratio of hydrophilic monomer. In addition, the grafting percentage and extent of grafting per area for the grafted membranes were also approximately linearly increased with increase in irradiation time until 40 min. Decreasing contact angle and increasing equilibrium water content confirmed that the wettability of modified SBS membrane was improved.