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Surface morphology of radiation-grafted binary copolymers measured in buffer solution under swelling condition

Abstract:

pH-dependent binary graft copolymers, [polypropylene (PP)-g-2- (dimethylarnino)ethylmethacrylate (DlvlAEMA)-g-fv'-isopropylaerylarnide (NIPAAm) and (PP-g-4-vinylpyrldine (4VP)-g-NlPAAml, synthesized by a two-step gamma-irradiation method, were characterized in terms of surface morphology under swelling condition. A confocal laser microscope with a water-immersion objective lens was employed for noncontact surface profile measurement of an extremely soft surface. Surface morphology was significantly different between these two binary copolymers, suggesting that the surface morphology of the binary copolymer reflected that of the first graft layer. Surface roughness was also analyzed as a function of the pH of the swelling buffer solution. Surface roughness increased with swelling ratio, and it further increased at lower pH, consistent with the results of a swelling ratio experiment previously reported. © 2010 The Japan Society of Applied Physics.