مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

The smart polymers are of particular interest due to their quick response to external environmental chemical and/or physical stimuli, such as temperature, pH, ionic strength, electric field, and photo-irradiation. These polymers may be used in many fields, such as protein adsorption, immobilization and separation, stimuliresponsive controlled releases and biotechnology. In the present work, a graft copolymer of poly(vinylidene fluoride) with poly(N-isopropylacrylamide) (PVDF-g-P(NIPAAm)) was synthesized by atom transfer radical polymerization (ATRP) directly using poly(vinylidene fluoride) (PVDF) as a macroinitiator. The copolymer can be readily cast into temperature-sensitive microfiltration membranes by the phase inversion technique. The effect of molar feed ratio of NIPAAm/PVDF on the properties of the copolymers was studied. The bulk and surface compositions of the membranes were obtained by elemental analysis and X-ray photoelectron spectroscopy (XPS), respectively. XPS results of the copolymer membranes obtained by phase inversion technique revealed a substantial surface enrichment of the grafted P(NIPAAm). The thermal stability of the copolymers was investigated by thermogravimetric analysis (TGA). The permeability of water through the pristine PVDF membrane exhibited the almost temperatureindependent flux behaviour. However, the rate of water flux through the PVDF -g-P(NIPAAm) membrane increased with the increase in permeate temperature from 20°C (below the LCST) to SO°C (above the LCST), with the most drastic increase being observed at the permeate temperature of about 32°C. The temperature-dependent permeation rate may result from the change in conformation of the P(NIPAAm) chains in the PVDF-g-P(NIPAAm) membrane. The thermoresponsive membranes obtained via the present approach may be applied to the biomedical and biotechnology fields.