Preparation of Two Step Thermo-Responsive Membrane with Tunable Separation Property and Improved Cleaning Efficiency

Abstract

We developed the two step thermo-responsive membrane with tunable selectivity and improved cleaning efficiency by introducing thermo-responsive block copolymer. To achieve this, we prepared poly (N, N-dimethylamino ehtylmethacrylate)-b-poly (N-isopropyl acryl-amides) (PDMAEMA -b-PNIPAM, PDN) which have two different lower critical solution temperature (LCST) behaviors. The two step thermo-responsive membrane (PES/PDN) was prepared with blending PDN block copolymer and poly (ether sulfone) by phase inversion method. Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) analysis identified that PDN block copolymers are successfully synthesized. Two step thermo-responsibility of PDMAEMA-b-PNIPAM was determined by proton nuclear magnetic resonance (1H NMR), dynamic light scattering (DLS). 1st aggregation occurred at 40 °C, and then 2nd aggregation occurred at 40-60 °C. Furthermore, successful preparation of PES/PDN membrane was confirmed by attenuated total reflectance Fourier transform infrared (ATR/FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis. Finally, filtration tests and fouling tests were carried out in order to demonstrate the tunable separation property and improved cleaning efficiency of the membrane. As expected, the PES/PDN membrane showed two step transition of permeability and rejection property at 40 °C and 50-70 °C. Likewise, cleaning efficiency of membrane increased when cleaning temperature is at 60 °C than at 30 °C. Therefore we demonstrated that two step thermo-responsive membrane was successfully prepared, and it could control the separation property and improve cleaning efficiency.