Temperature-dependent molecular-recognizable membranes based on poly(N-isopropylacrylamide) and β-cyclodextrin

A novel temperature-dependent molecular-recognizable membrane, poly(N-isopropylacylamide-co-glycidyl methacrylate/cyclodextrin)-grafted-polyethylene terephthalate (P(NIPAM-co-GMA/CD)-g-PET) membrane, is prepared by the combination of plasma-induced pore-filling grafting polymerization and chemical reaction. Scanning electron microscope (SEM) images show that the surfaces and cross-sections of the prepared membranes are uniformly grafted by polymeric layer. Fourier transform infrared (FT-IR) results show that CDs are successfully induced onto the P(NIPAM-co-GMA) grafted chains through reaction with epoxy groups. When the environmental temperature increases from 25 °C to 45 °C, the contact angle of prepared P(NIPAM-co-GMA/CD)-g-PET membrane increases from 65° to 76.9°; whereas, that of substrate membrane decreases from 84.8° to 77.1°. During the dynamic adsorption experiments, the guest 8-anilino-1-naphthalenesulfonic acid ammonium salt (ANS) molecules are adsorbed onto the P(NIPAM-co-GMA/CD)-g-PET membrane at lower temperature (25 °C) and desorbed from it at higher temperature (40 °C) with good repeatability. This phenomenon of adsorption at low temperature and desorption at high temperature of the P(NIPAM-co-GMA/CD)-g-PET membrane is attributable to both the “swollen–shrunken” configuration change of P(NIPAM-co-GMA) grafted chains and the molecular recognition of CD toward ANS. The P(NIPAM-co-GMA/CD)-g-PET membrane show both good thermo-responsibility and temperature-dependent molecular-recognizable characteristics toward guest molecules, which is highly potential to be applied in temperature-controlled affinity separations.