Ethanol‐responsive characteristics of polyethersulfone composite membranes blended with poly(N‐isopropylacrylamide) nanogels

Abstract

Ethanol‐responsive smart membranes with different microstructures are prepared from blends of polyethersulfone (PES) and poly(N‐isopropylacrylamide) (PNIPAM) nanogels by immersion precipitation phase inversion method in a convenient and controllable manner. The introduction of PNIPAM nanogels forms the microporous structures on the surface of the top skin layer and on the pore walls of the finger‐like porous sublayer of membranes. The ethanol‐responsive characteristics of the proposed PES composite membranes are systematically investigated. With increasing ethanol concentration in the range from 0 to 15 wt %, the trans‐membrane flux of ethanol solution increases. The microstructures and the resultant ethanol‐responsive characteristics of the composite membranes can be regulated by the content of PNIPAM nanogels blended in the membranes. The more the content of PNIPAM nanogels blended in the membranes, the more the number of the submicron pores is, and thus the better the ethanol‐responsive characteristics of the composite membranes. The proposed ethanol‐responsive smart membranes are expected to be combined with the traditional pervaporation membranes as a smart vavle to achieve continuous and highly efficient ethanol production during the biological fermentation. The preparation technique and results in this study provide valuable guidance for further design and the industrial‐scale fabrication of novel composite membranes for application in ethanol separation systems. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41032.

Ethanol‐Responsive Poly(Vinylidene Difluoride) Membranes with Nanogels as Functional Gates

“…The low water permeability across the blended membranes results from both the high resistance for permeation due to pore walls of the cellular‐like pore structure, and the swollen PNIPAM nanogels on the pore walls at 20 °C which is lower than the volume phase transition temperature (VPTT) of PNIPAM. The VPTT of PNIPAM nanogels in water is around 33 °C 20.…”

“…The permeability of membrane J is defined as the mass of transmembrane feed solution per unit membrane area and time 20. The continuous permeability of feed solution with a certain ethanol concentration was determined after recording the mass of transmembrane ethanol solution and the corresponding time was generally less than 1 min.…”

“…The third approach to prepare stimuli‐responsive membranes is blending stimuli‐responsive polymers into membranes as an additive, followed by membrane formation such as liquid‐induced phase separation (LIPS) and solvent evaporation, which is a continuous process 12, 13, 20. Ying et al 13 prepared pH‐ and thermo‐responsive microfiltration membranes from blends of poly(acrylic acid)‐grafted PVDF (PAAc‐ g ‐PVDF) copolymer and PNIPAM homopolymer in N ‐methyl‐2‐pyrrolidone (NMP) solution by phase inversion in water at 25 °C.…”

“…PNIPAM has satisfactory thermo‐responsive and ethanol‐responsive characteristics and acts as self‐assembling functional gates. The ethanol‐responsive membranes have potentials to apply in ethanol separation systems 20, 29. The process parameters including relative humidity and temperature of vapor, exposure time, dissolution temperature of casting solution etc.…”

Preparation of polymer of intrinsic microporosity composite membranes and their applications for butanol recovery

“…To ease the energy crisis and reduce environmental pollution, acetone–butanol–EtOH fermentation has been used to produce biofuels to replace conventional fossil fuels . Although the fermentation course is halted when the final product concentration [especially of butanol, which practically takes up 60 wt % (average weight ratio) of acetone–butanol–EtOH] exceeds a certain level, a range of conventional technologies, such as distillation and CO 2 extraction, have been used to handle this problem.…”