Preparation, characterization, and applicability of novel calix[4]arene-based cellulose acetate membranes in gas permeation



Cellulose acetate (CA) is well known glassy polymer used in the fabrication of gas-separation membranes. In this study, 5,11,17,23-tetrakis(N-morpholinomethyl)-25,26,27,28-tetrahydroxycalix[4]arene (CL) was blended with CA to study the gas-permeation behavior for CO2, N2, and CH4 gases. We prepared the pure CA and CA/CL blended membranes by following a diffusion-induced phase-separation method. Three different concentrations of CL (3, 10, and 30 wt %) were selected for membrane preparation. The CA/CL blended membranes were then characterized via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction analysis. The homogeneous blending of CL and CA was confirmed in the CA/CL blended membranes by both SEM and AFM analysis. In addition to this, the surface roughness of the CA/CL blended membranes also increased with increasing CL concentration. FTIR analysis described the structural modification in the CA polymer after it was blended with CL too. Furthermore, CL improved the tensile strength of the CA membrane appreciably from 0.160 to 1.28 MPa, but this trend was not linear with the increase in the CL concentration. CO2, CH4, and N2 gases were used for gas-permeation experiments at 4 bars. With the permeation experiments, we concluded that permeability of N2 was higher in comparison to those of CO2 and CH4 through the CA/CL blended membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39985.