Preparation and methanol detection performance of alcohol-responsive smart membranes
Poly(N-n-propylacrylamide)(PNN),poly(N-isopropylacrylamide)(PNI)and poly(N-isopropylmethacrylamide)(PNM)microspheres with different hydrophilicity were fabricated by precipitation polymerization.The alcohol-responsive membranes for methanol detection at room temperature were successfully prepared by physically blending such microspheres into polyvinylidene fluoride(PVDF)membrane materials followed by liquid induced phase separation(LIPS).The thermo-responsive and alcohol-responsive characteristics of microspheres,effect of hydrophilic properties of microspheres on the microstructure,surface chemical composition as well as the responsive properties of membranes in methanol,ethanol and methanol-ethanol mixed solutions were systematically investigated.The results show that the thickness,pore size and porosity of alcohol-responsive membranes increased significantly with the increase of hydrophilicity of microspheres.The thickness,pore size and porosity of the PVDF/PNM membranes blended with the most hydrophilic PNM microspheres reached to the maximum,were 2.4 times,4.7 times and 5.9 times of those of the blank membranes,respectively.The maximal permeability(Pmax)and critical alcohol response volume fraction of membranes affected by the operation temperature,types of alcohol aqueous solution and the hydrophilicity of microspheres.The PVDF/PNM membranes show the largest variance in the responsivity of ethanol and methanol,and the difference in the critical methanol response volume fraction(CM)and critical ethanol response volume fraction(CE)at 40 ℃ reached 6.5％.With the increase of the proportion of methanol in the mixed solution with total volume fraction of 40％at 25 ℃,the membrane permeability showed a good linear relationship with the methanol volume fraction,and the methanol volume fraction in the mixed solution could be calculated by the permeability.These results provide a new idea for the facile detection of methanol concentration.
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维普
