Preparation and characterization of PVA membrane modified by water-soluble hyperbranched polyester (WHBP) for the dehydration of n-butanol

Water-soluble hyperbranched polyester (WHBP) was synthesized through the esterification reaction of the fourth generation hyperbranched polyester and maleic anhydride. A novel cross-linked WHBP/PVA membrane was prepared by adding WHBP into poly(vinyl alcohol) (PVA) solution with glutaraldehyde as the cross-linker. WHBP was characterized by Nuclear Magnetic Resonance and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), while WHBP/PVA membranes were characterized by ATR-FTIR, X-ray Diffraction, Scanning Electron Microscopy, Thermogravimetric Analysis, mechanical capacity, and water contact angle. Testing results showed that maleic anhydride was grafted on the surface of WHBP; compared with PVA membrane, WHBP/PVA membrane had lower crystallinity, weaker mechanical strength, higher hydrophilicity, and better thermal stability. Sorption and diffusion behaviors of n -butanol and water in WHBP/PVA membrane were investigated; pervaporation performances of WHBP/PVA membrane were studied through the dehydration of the 90 wt % n -butanol aqueous solution at 40°C. With an increase of the WHBP content from 0 to 30 wt %, both n -butanol uptake and n -butanol diffusion coefficient first decreased then increased; n -butanol flux first decreased from 10 to 2 g·m −2 ·h −1 then increased to 213 g·m −2 ·h −1 ; both sorption selectivity and diffusion selectivity first increased then decreased; separation factor first increased from 88 to 1309 then decreased to 16. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43533.