Ion Track Technology

PhysicsConsult

Reimar Spohr

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Permeation of p-nitrophenol through N-isopropylacrylamide-grafted etched-track membrane close to theta-point temperature. Akihiro Hiroki, Masaru Yoshida, Noriyasu Nagaoka, Masaharu Asano, Nicole Reber, Reimar Spohr, Hitoshi Kubota, Ryoichi Katakai. Radiation Effects and Defects in Solids, 147, 165-175 (1999)

Thermo-responsive poly(N-isopropylacrylamide, NIPAAm) was grafted onto etched-track copolymer films with cylindrical pores of diameter 2.5 μm by means of post-polymerization at 60°C for 30 min after pre-irradiation of 30 kGy, using γ-rays from a 60Co source to obtain a layer with a surface graft yield of 0.18 mg/cm2. The permeation of p-nitrophenol (PNP) through NIPAAm-grafted etched-track films, when measured at 30°C, was markedly depressed, to 7.12×10-5 cm/min, compared with those measured below and above this temperature, e.g. 3.84×10-3 cm/min at 29°C and 2.46×10-3 cm/min at 31°C. This phenomenon can be explained by the existence of a theta-point (Θ) temperature, at which the hydrophilic interaction between the linear polymer of NIPAAm and water apparently disappears, resulting in permeation retardation of the water soluble PNP (44 refs.)