Effect of coagulation media on membrane formation and vapor permeation performance of novel aromatic polyamide membrane

In the present work, a novel aromatic polyamide was prepared by direct polymerization of 4,4′-hexafluoroisopropylidenedibenzoic acid with diamine of 2,2′-dimethyl-4,4′-bis(aminophenoxy)diphenyl by triphenyl phosphite and pyridine in N-methyl-2-pyrrolidinone. The effects of coagulation media on the membrane morphology and the vapor permeation performances of aqueous ethanol solution through wet phase inversion prepared asymmetric polyamide membrane were investigated. The Young’s modulus increases and membrane porosity of the asymmetric polyamide membrane decreases with increasing the molar volume of coagulation medium. The diffusivity of coagulation medium ranks in the following order: water>methanol>ethanol>n-propanol. The membrane morphology and membrane formation properties were characterized by SEM, Fourier transform infrared (FT-IR)–attenuated total reflectance (ATR), light transmission, and DMA, etc. Optimum vapor permeation results, a separation factor of 21 and permeation rate of 657 g/m2 h, were obtained with the asymmetric polyamide membrane prepared from the ethanol (coagulation medium) system.