• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.156-159
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• 2004

• Macromolecular Research
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• v.17 no.5
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• pp.325-331
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• 2009

The synthesis and the characterization of crosslinked ABC triblock copolymer, i.e. polystyrene-b-poly (hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid), (PS-b-PHEMA-b-PSSA) is reported. PS-b-PHEMA-b-PSSA triblock copolymer at 20:10:70 wt% was sequentially synthesized via atom transfer radical polymerization (ATRP). The middle block was crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA, as demonstrated by FTIR spectroscopy. As increasing amounts of SA, ion exchange capacity (IEC) continuously increased from 2.13 to 2.82 meq/g but water uptake decreased from 181.8 to 82.7%, resulting from the competitive effect between crosslinked structure and the increasing concentration of sulfonic acid group. A maximum proton conductivity of crosslinked triblock copolymer membrane at room temperature reached up to 0.198 S/cm at 3.8 w% of SA, which was more than two-fold higher than that of Nafion 117(0.08 S/cm). Transmission electron microscopy (TEM) analysis clearly showed that the PS-b-PHEMA-b-PSSA triblock copolymer is microphase-separated with a nanometer range and well developed to provide the connectivity of ionic PSSA domains. The membranes exhibited the good thermal properties up to $250^{\circ}C$ presumably resulting from the microphase-separated and crosslinked structure of the membranes, as revealed by thermal gravimetric analysis (TGA).

• Clean Technology
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• v.11 no.3
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• pp.141-146
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• 2005

The composite membranes were made by grafting using supercritical carbon dioxide (scCO2) impregnation and polymerization procedures. The membranes were synthesized by changing amount of monomer. The polypropylene grafted polystyrene sulfonic acid (PP-g-pssa) membranes were characterized with various methods. The morphology and structure of PP-g-pssa membranes were analyzed with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). As amount of monomer was increased, ion conductivity, cell performance was increased and methanol permeability was decreased. However PP-g-pssa membranes with 1.5g monomer and over had similar values of methanol permeability, ion conductivity and cell performance.

• Membrane Journal
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• v.28 no.5
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• pp.361-367
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• 2018

In this study, the nanofiltration (NF) composite membranes for the low pressure use were prepared using polyvinylidene fluoride (PVDF) hollow fiber membrane as a supporter. Poly styrene sulfonic acid (PSSA) and polyethyleneimine (PEI) were coated onto the PVDF membrane by both layer-by-layer and salting-out methods. To characterize the prepared NF membranes in terms of the flux and salt rejection, 100 mg/L feed solutions of NaCl, $MgCl_2$, and $CaSO_4$ were used at the flow rate of 1 L/min and the operating pressure of 2 bar at room temperature. The NF membranes coated with 20,000 ppm PSSA (ionic strength 1.0) solution for 3 minutes and then 30,000 ppm (ionic strength 0.1) solution for 1 minute were observed the best performance. The permeability and salt rejection were 38.5 LMH, 57.1% for NaCl, 37.9 LMH and 90.2% for $MgCl_2$ and 32.4 LMH and 54.6% for $CaSO_4$, respectively.

• Membrane Journal
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• v.21 no.1
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• pp.39-45
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• 2011

An amphiphilic graft copolymer consisting of a poly(vinyl chloride) (PVC) backbone and poly(styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). This polymer electrolyte membrane was ion-exchanged to Ag ions by immersing in 10 wt% $AgNO_3$ aqueous solution and templated the growth of Ag nanoparticles by a reducing agent. The formation of Ag nanoparticles was confirmed using UV-visible spectroscopy and X-ray diffraction (XRD). Transmission electron microscopy (TEM) revealed that utilization of $NaBH_4$ was the most effective in the formation of Ag nanoparticles with 10~15 nm in size. The formation of Ag nanoparticles was also strongly affected by the concentration of reducing agent and reduction time.

• Membrane Journal
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• v.25 no.6
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• pp.538-546
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• 2015

In this study, composite membrane is prepared by Layer-by-Layer method using hydrophobic polymer as a coating material on the polysulfone support. The existence of coating layer on the surface and cross section was confirmed by the scanning electronic microscopy. The flux and rejection of the resulting membranes were characterized using 100 ppm NaCl feed solution. PVSA, PEI, PAA, PSSA, PSSA_MA were used as a coating polymer in this study. The composite membrane prepared by using 8,000 ppm PAA solution (Ion strength = 0.35, Coating time = 3 min) and 10,000 ppm PEI solution (Coating time = 4 min). As a result, PAA-PEI composite membrane showed flux of 101 LMH and salt rejection of 66.7%. The composite membrane showed the comparable performance as good as NE 4040-70 (Flux = 30 LMH, Rejection = 40~70%) model produced by Toray Chemical co.

• Membrane Journal
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• v.29 no.2
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• pp.96-104
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• 2019

The purpose of this paper is whether or not the in-situ restoration of the reverse osmosis (RO) membranes which its membrane function is lost is possible. The damaged RO membranes are double coated through the salting-out method by the poly(styrene sulfonic acid) sodium salt as the cationic exchange polymer and the polyethyleneimine as the anionic exchange polymer and also conducted the opposite order of the coating materials. And according to the concentration, time and ionic strength, the flux and rejection are measured for the coated membranes. Then the best coating condition is to apply for the RO membrane module of the household water purifier to know the possibility of the in-situ restoration for the commercial module. When the condition of the PEI 30,000 ppm (IS = 0.1)/PSSA 20,000 ppm (IS = 0.7) is applied, the rejection was enhance from 69% for the damaged module to 86% (90% for the pristine module).

• Membrane Journal
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• v.29 no.3
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• pp.140-146
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• 2019

In this study, a selective layer of poly styrene sulfonic acid (PSSA) and polyethyleneimine (PEI) was formed by layer-by-layer method onto a porous polyacrylonitrile (PAN) hollow fiber membrane as the suppoter membrane. The salting out method was used by adding Mg salt to the coating solution. Several experimental conditions of the ionic strength, polymer concentration, and coating time were investigated, and the flux and rejection were measured at the operating pressure of 2 atm for 100 mg/L of NaCl, $MgCl_2$, and $CaSO_4$ as the feed solution. The membranes coated with PSSA 20,000 ppm, coating time 3 minutes, ionic strength 1.0, PEI 30,000 ppm, coating time 1 minute, and ionic strength 0.1 were observed the best. In the 100 ppm NaCl, $MgCl_2$, and $CaSO_4$ feed solutions, the flux of 20.4, 19.4, and 18.7 LMH, and the rejection of 67, 90, and 66.6%, respectively.

• Polymer(Korea)
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• v.34 no.1
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• pp.20-24
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• 2010

In this study, ETFE-g-PSSA membranes with various degrees of grafting (DOG) and thicknesses were prepared by a simultaneous irradiation method. SEM-EDX instrument was applied to measure the relative distribution of sulfur which is corresponding to that of a grafted polymer over the Cross-section of the ETFE-g-PSSA membranes prepared at various irradiation conditions. The results indicate that to obtain the evenly-grafted membranes, a styrene/dichloromethane ratio is needed to be under 60 (v/v%), and a higher DOG is required as the film thickness increases. The effects of DOG and thickness on the ion exchanging capacity (IEC) and water uptake (WU) were investigated by measuring the IEC and WU values of the membranes with various DOG and thicknesses.

• Membrane Journal
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• v.19 no.2
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• pp.96-103
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• 2009

A series of organic-inorganic composite membranes from poly(vinyl chloride) (PVC) graft copolymer electrolyte and heteropolyacid (HPA) were prepared for proton conducting membranes. First, poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA) was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC. HPA nanoparticles were then incorporated into the PVC-g-PSSA graft copolymer though the hydrogen bonding interactions, as confirmed by FT-IR spectroscopy. The proton conductivity of the composite membranes increased from 0.049 to 0.068 S/cm at room temperature with HPA contents up to 0.3 weight traction of HPA, presumably due to both the intrinsic conductivity of HPA particles and the enhanced acidity of the sulfonic acid of the graft copolymer. The water uptake decreased from 130 to 84% with the increase of HPA contents up to 0.45 of HPA weight traction, resulting from the decrease in number of water absorption sites due to hydrogen bonding interaction between the HPA particles and the polymer matrix. Thermal gravimetric analysis (TGA) demonstrated the enhancement of thermal stabilities of the composite membranes with increasing concentration of HPA.