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A pilot-scale sustainable hydrogen production system using reverse electrodialysis (RED) technology was launched. The system is based on direct conversion of salinity gradient energy (SGE) between seawater (SW) and sewage treated water (STW) to hydrogen production by water electrolysis. The hydrogen production rate was almost the same as the theoretical value. This indicates that the RED hydrogen production system can convert SGE between SW and STW to hydrogen energy at high current efficiency.

In industrial electrodialysis (ED) processes, to ensure a stable and reliable operation for a long period, alkaline cleaning processes, such as cleaning in place (CIP), are often used to suppress fouling of anion exchange membranes (AEMs). However, alkali CIP causes a reduction in the AEM performance, especially for AEMs containing polyvinyl chloride (PVC) as backing cloth and/or binder. To clarify the relationship between alkali attack and performance reduction of AEMs quantitatively, an alkali immersion test was conducted using a commercially available AEM containing PVC, with different immersion times, at various temperatures and NaOH concentrations, to obtain test pieces. Electrochemical and mechanical measurements of the test pieces revealed a reduction in Young’s modulus and subsequent increase in water content of the AEMs and resulted in a reduction of the electrical resistance and proton rejection of the AEMs. ATR-FTIR and XRF analyses support that dehydrochlorination of PVC and production of polyene in the AEMs by alkali resulting in such performance reductions. Visible light (VIS) absorption and microscopic observation of the test pieces showed that polyene was produced in the backing cloth and binder. Moreover, using the VIS absorbance data, a prediction method for performance reduction in an AEM was proposed.

Salinity gradient between two solutions can be transformed to an electrical power by reverse electrodialysis (RED) process which comprises of alternatively cation exchange membrane (CEM), dilute solution, anion exchange membrane (AEM) and concentrate solution. Although spacers are generally equipped between the membranes to keep their intermediate distance, the presence of them also have a significant effect on RED stack resistance, often called as spacer shadow effect. In this study, the spacer shadow effects on both membrane and solution compartment resistances are investigated by using 16 spacers having different geometries with 56–84% porosity and 0.100–0.564 mm thickness. In addition, we search and propose the suitable spacer geometric parameter for estimating these spacer shadow effects. The results indicate that the spacer shadow effect on membrane has a good correlation with a parameter consisting of area fraction and diameter of spacer filaments, whereas, a parameter consisting of both area and volume fractions of the spacer agreed well with those on solution compartment in a wide range of spacer geometric condition. These results are useful for not only estimating the spacer shadow effect on both membrane and solution resistances for enhancing the subsequent RED power output performance, but also designing a suitable spacer geometry specified for RED.

Reverse electrodialysis (RED) is a promising process for harvesting energy from the salinity gradient between two solutions without environmental impacts. Seawater (SW) and river water (RW) are considered the main RED feed solutions because of their good availability. In Okinawa Island (Japan), SW desalination via the reverse osmosis (RO) can be integrated with the RED process due to the production of a large amount of RO brine (concentrated SW, containing ~1 mol/dm3 of NaCl), which is usually discharged directly into the sea. In this study, a pilot-scale RED stack, with 299 cell pairs and 179.4 m2 of effective membrane area, was installed in the SW desalination plant. For the first time, asymmetric monovalent selective membranes with monovalent selective layer just at the side of the membranes were used as the ion exchange membranes (IEMs) inside the RED stack. Natural and model RO brines, as well as SW, were used as the high-concentrate feed solutions. RW, which was in fact surface water in this study and close to the desalination plant, was utilized as the low-concentrate feed solution. The power generation performance investigated by the current-voltage (I&ndash, V) test showed the maximum gross power density of 0.96 and 1.46 W/m2 respectively, when the natural and model RO brine/RW were used. These are a 50&ndash, 60% improvement of the maximum gross power of 0.62 and 0.97 W/m2 generated from the natural and model SW, respectively. The approximate 50% more power generated from the model feed solutions can be assigned to the suppression of concentration polarization of the RED stack due to the absence of multivalent ions.

An alkali treatment under various operating conditions is conducted on a commercial anion-exchange membrane containing poly(vinyl chloride) (PVC) as a backing and binder to study the effect of the treatment on the mechanical properties by both M&uuml, llen burst and tensile tests. Contrary to our expectations, the M&uuml, llen burst pressure and tensile strain at break improved significantly after the alkali treatment in comparison to the pristine membrane and then decreased as the treatment period progressed. A good correlation is observed between the area below the stress&ndash, strain curve and burst pressure. To understand the obtained results, the PVC degradates are recovered by Soxhlet extraction and characterized via nuclear magnetic resonance and gel permeation chromatography. It is discovered that the PVC main chains degraded in the alkali solution. We propose a composite model to explain the burst pressure improvement mechanism by the change in the chemical structure of the PVC binder.

Although the treatment of municipal wastewater using microbial fuel cells (MFCs) has been extensively studied, scaling the systems up for practical use remains challenging. In this study, a 226 L sewage treatment reactor was equipped with 27 MFC units, and its chemical oxygen demand (COD) removal and electricity production were evaluated. The MFC units were tubular air cores with a diameter of 5 cm and length of 100 cm, which were wrapped with a carbon-based cathode, anion exchange membrane (AEM), and nonwoven graphite fabric. The air-cathode–AEM MFC generated 0.12–0.30 A/m2, 0.072–0.51 W/m3, and 1.7–4.6 Wh/m3 in a chemostat reactor with a COD of 140–36 mg/L and hydraulic retention time (HRT) of 9–42 h throughout a year. The decrease in the COD was represented as the first-order rate constant of 0.038. The rate constant was comparable to that of other air-cathode MFCs with cation exchange membranes, indicating the necessity of a posttreatment to meet the discharge standard. It has been estimated that the MFC operation for 24 h before post-aeration can reduce the energy required to meet the discharge standard by 70%, suggesting the potential applicability of MFC in long HRT-treatments such as oxidation ditch. The resistances of the anode, cathode, and AEM were 0.60, 0.28, and 0.51 mΩ m2, respectively, and surface dirt rather than deterioration primarily increased the AEM resistance. A current exceeding 0.2 A/m2 significantly increases the anode potential, indicating that the current was limited by low COD. Increasing the anode-specific surface area can improve air–AEM MFCs used for practical applications.

In this work, we present a simple one step blending modification method to fabricate antibacterial PVDF membrane. Effect of membrane surface material properties on the antibacterial activity was investigated. Firstly, a cationic copolymer containing quaternary ammonium cations was synthesized by free radical polymerization of methyl methacrylate (MMA) and dimethylamino-2-ethyl methacrylate (DMAEMA), and following quaternization by iodomethane as an alkylating agent. Via a one-step non-solvent induced phase separation (NIPS) process, blend PVDF membranes were prepared with the copolymers as additive. Only a small amount of copolymer addition (0.9 wt.%) profoundly improved antibacterial activity of the obtained membranes surafce against Escherichia coli (E. coli), as a typical model micro-organism foulant, due to enhanced hydrophilicity and incorporation of quaternary ammonium groups on the membrane surface. In particular, the quaternized copolymer using iodomethane imparted the optimized antibacterial performance with both high adhesion resistance (surface occupying, 15%) and high inactivation (cell viability, 0.15%) to E. coli cells.

Impregnation of the noble metal, silver nanoparticles (AgNPs) as a disinfectant into the polymeric membrane is one of the empirical modification methods in producing safe drinking water. However, the dispersion and immobilization of AgNPs during membrane fabrication and application is least discussed despite numerous leaching phenomena reported. In this study, silver nanoparticles type 1 (AgNPs-1) and type 2 (AgNPs-2) were prepared and incorporated into polyvinylidene fluoride (PVDF) ultrafiltration membrane with the presence of thermal treatment. The effect of thermal treatment was studied at temperature 25 °C, 40 °C and 55 °C which significantly influenced the physicochemical characteristics of the PVDF membrane. Membrane incorporated with AgNPs-1 and AgNPs-2 fabricated at highest temperature portrayed improved mechanical properties and pure water flux. PVDF/PVP/AgNPs-2 membrane released the smallest amount of Ag (3.81%) while PVDF/PVP/AgNPs-1 cast at 40 °C released the largest amount of Ag (42.34%) during the phase inversion at fabrication. Notably, no Ag leaching was found in all membranes during the dead-end filtration at 0.5 bar. Membranes with AgNPs-1 and AgNPs-2 showed remarkable bactericidal performance towards E. coli with a percentage reduction of 90.38% and 80.77%, respectively. Thus, membranes with AgNPs fabricated at 55 °C offered better mechanical properties of the enhanced permeability and excellent stability of AgNPs immobilization which signified the thermal treatment approach.

To improve the antifouling properties of polymer membranes, a novel phosphate-based zwitterionic polymer (methacryloyloxyethylphosphorylcholine-co-poly(propylene glycol) methacrylate, i.e., MPC-PPGMA) is introduced into the polyvinyl chloride (PVC) membrane matrix. The solubility of this zwitterionic copolymer in common organic solvents and the compatibility between this copolymer and PVC are studied. A series of PVC blend membranes are prepared via non-solvent induced phase separation based on the good compatibility of the copolymer with PVC. Surface chemical compositions, wettability and porous structures of the membranes are characterized. Fluorescence-labeled proteins static adsorption and organic foulant filtration are conducted to evaluate the fouling resistance of the blend membranes. Antibiofouling properties of the membranes are also confirmed by the immersing method. Doping MPC-PPGMA in the casting solution can significantly improve the surface hydrophilicity and antifouling properties of the PVC blend membranes due to the strong hydration ability of the zwitterionic segments. The blend membranes show excellent and stable resistance to both organic fouling and biofouling. Overall, the novel zwitterionic copolymer MPC-PPGMA is a promising candidate to develop antifouling blend membranes due to its high effectiveness and long-term stability in the membranes.

Hollow fiber type cation-exchange (C-HF) membranes and hollow fiber type anion-exchange (A-HF) membranes were prepared from poly (vinyl alcohol) (PVA)-based copolymer with cation-exchange groups and by blending PVA and polycation, respectively, by a gel fiber spinning method. In order to control the water content of the hollow fiber membranes, the membranes were cross-linked physically by annealing, and then cross-linked chemically by using glutaraldehyde (GA) solutions at various GA concentrations. The outer diameter of C-HF and A-HF membranes were ca. 1000 &mu, m and ca. 1500 &mu, m, respectively, and the thickness of the membranes were ca. 170 &mu, m and 290 &mu, m, respectively. Permeation experiments were carried out in two Donnan dialysis systems, which included mixed 0.1 M NaCl and 0.1 M CaCl2/C-HF /3 &times, 10&minus, 4 M CaCl2 and mixed 0.1 M NaCl and 0.1 M NaNO3/A-HF/3 &times, 4 M NaNO3 to examine ionic perm selectivity of the membranes. In the Donnan dialysis experiments using C-HF membranes, uphill transport of the divalent cations occurred, and, in the case of A-HF membranes, uphill transport of NO3&minus, ions occurred. C-HF and A-HF membranes had about half of the flux in the uphill transported ions and also about half of the selectivity between the uphill transport ions and driven ions in comparison with those of the commercial flat sheet cation-exchange membrane (Neosepta&reg, CMX) and anion-exchange membrane (Neosepta&reg, AMX). Yet, IEC of C-HF and A-HF membranes were about one fifth of CMX and less than half of AMX, respectively. Since hollow fiber membrane module will have higher packing density than a flat membrane stack, the hollow fiber type ion-exchange membranes (IEMs) prepared in this study will have a potential application to a Donnan dialysis process.

Pressure-retarded osmosis (PRO) has recently received attention because of its ability to generate power via an osmotic pressure gradient between two solutions with different salinities: high- and low-salinity water sources. In this study, PRO performance, using the two pilot-scale PRO membrane modules with different configurations—five-inch cellulose triacetate hollow-fiber membrane module (CTA-HF) and eight-inch polyamide spiral-wound membrane modules (PA-SW)—was evaluated by changing the draw solution (DS) concentration, applied hydrostatic pressure difference, and the flow rates of DS and feed solution (FS), to obtain the optimum operating conditions in PRO configuration. The maximum power density per unit membrane area of PA-SW at 0.6 M NaCl was 1.40 W/m2 and 2.03-fold higher than that of CTA-HF, due to the higher water permeability coefficient of PA-SW. In contrast, the maximum power density per unit volume of CTA-SW at 0.6 M NaCl was 4.67 kW/m3 and 6.87-fold higher than that of PA-SW. The value of CTA-HF increased to 13.61 kW/m3 at 1.2 M NaCl and was 12.0-fold higher than that of PA-SW because of the higher packing density of CTA-HF.

The antifouling properties of poly(vinylidene fluoride) (PVDF) membranes were investigated by blending several types of synthesized amphiphilic poly(poly(ethylene glycol) methyl ether methacrylate- methyl methacrylate) [P(PEGMA- MMA)] copolymers with different initial PEGMA/MMA monomer ratios and PEG side chain lengths. Many types of membranes were prepared using different copolymer/PVDF blend ratios via nonsolvent induced phase separation. The membranes with similar pure water permeabilities and surface pore sizes were prepared by controlling the dope solution composition. Thus, the bovine serum albumin antifouling properties could be assessed under similar hydrodynamic filtration conditions. The membrane hydrophilicity, surface PEGMA coverage, and antifouling properties of the prepared membranes increased with increasing copolymer/PVDF ratio and PEGMA/MMA monomer ratio of the copolymers and PEG length of the copolymer. A molecular dynamics simulation was performed to assess the surface chemical composition, and the results were compared with those of X-ray photoelectron spectroscopy. The antifouling properties depended more strongly on the membrane surface hydrophilicity when the copolymer chemical structures, that is, the PEGMA/MMA monomer ratio and PEG side chain length, were changed, rather than when the copolymer/PVDF blend ratio was changed.

Several membranes with low fouling properties were prepared by blending PVC with poly(vinyl chloride-co-poly(ethylene glycol) methyl ether methacrylate) (poly(VC-co-PEGMA)) copolymer via a non-solvent induced phase separation (NIPS) method. Bovine serum albumin adsorption on polymer films decreased and the membrane surface pore sizes, hydrophilicities, and antifouling properties increased on increasing the poly(VC-co-PEGMA)/PVC blending ratio. Membrane surface PEGMA coverage increased on increasing the poly(VC-co-PEGMA)/PVC blending ratio, resulting in higher hydrophilicities and lower fouling propensities. Membranes with similar water permeabilities were prepared by adjusting the dope solution composition to eliminate the effect of hydrodynamic conditions on membrane fouling performance. The effect of the membrane material on the membrane fouling propensity was much stronger than that of the membrane surface structure. Molecular dynamics simulations were performed to evaluate the surface chemical composition of the membrane matrix and results were compared with results obtained from XPS measurements.

Two series of antifouling microfiltration membranes (MF) with different pure water permeabilities were fabricated using poly(vinyl chloride-co-poly(ethylene glycol)methyl ether methacrylate) (poly(VC-co-PEGMA)) copolymers with different PEGMA segment percentage via nonsolvent-induced phase separation (NIPS) method. Membranes with similar water permeability were obtained for each series by changing the dope solution composition, because the water permeability can affect the membrane fouling property. Bovine serum albumin (BSA) adsorption on copolymer films decreased and membrane surface pore size, hydrophilicity, and antifouling properties increased by increasing the PEGMA segment percentage. BSA filtration results revealed that the hydrophilicity of the membrane and the initial water flux more strongly affected the fouling propensity than the membrane surface pore size. Molecular dynamics simulation was carried out to investigate the state of the PEGMA on the membrane surface for clarifying the fouling mechanism.

Systematic alkali immersion tests of cation-exchange membranes (CEM) with polyvinyl chloride (PVC) as their backing and binder were conducted to compare that of an Anion-exchange membrane (AEM) with the same PVC materials to investigate the mechanism of dehydrochlorination. In the immersion tests, originally colorless and transparent AEM turned violet, and chemical structure analysis showed that polyene was produced by the dehydrochlorination reaction. However, the CEM did not change in color, chemical structure or membrane properties during the test with less than 1M alkali solutions. According to the Donnan equilibrium theory and the experiments using CEM and AEM, the hydroxide ion concentration in the CEM was much lower than that in the AEM under the same conditions. However, when the alkali immersion test was performed using the CEM under more severe conditions (6 M for 168 h at 40 &deg, C), there was a slight change in the color and chemical structure of the CEM, clearly indicating that not only AEMs, but also CEMs with PVC matrixes were deteriorated by alkali, depending on the conditions.

Direct methanol alkaline fuel cells (DMAFCs) with anion exchange membranes (AEMs) have the potential to address many of the problems faced by their acidic counterparts made with proton exchange membranes. Polyvinyl alcohol (PVA) is a candidate material for polymer electrolyte membranes (PEMs) for DMAFCs due to its excellent methanol barrier properties. In this study, PVA-based PEMs for a DMAFC process were prepared from PVA-based block copolymers with varying glutaraldehyde (GA) cross-linker concentrations. The properties and DMAFC performance of the PVA-block type PEMs at various concentrations of methanol were measured and compared with a commercially available AEM, Neosepta® AMX. A single cell DMAFC test using the PEM cross-linked with 0.01 vol% GA and AMX produced the maximum power of 99.6 mW/cm2 and 15.2 mW/cm2, respectively. When the methanol concentration was increased to 10 wt%, the PEM produced 94.8 mW/cm2, while AMX produced significantly less power at 7.7 mW/cm2 under the same conditions. Even at the high methanol concentration of 30 wt%, the PEM produced 42.2 mW/cm2, while AMX did not generate any power under the same conditions.

Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes

The diameter of the hollow fiber membrane is of great importance in relation to space efficiency in a membrane module. The die-swell effect is one of the major contributors to the membrane diameter during nonsolvent induced phase separation (NIPS) by wet spinning. In this study, we investigate the effects of viscoelasticity and solidification rate of the polymer solution on the die-swell effect and diameter of hollow fiber membrane during NIPS in the spinning process. We characterized the rheological properties and solidification rates of the polymer solutions during phase separation. The die swell in hollow fiber spinning and the cross-sections of the prepared hollow fiber membranes were then determined. From the results, the outer and inner diameters of the hollow fiber membranes increased and decreased due to die swell, respectively, with increasing first normal stress difference. Furthermore, decreasing solidification rate of the polymer solution enhanced die swell and significantly affected the outer and inner diameters of the prepared hollow fiber membrane. Surprisingly, the solidification rate of the inner solution influenced die swell and significantly affected not only the inner diameter but also the outer diameter.

Anion-exchange membranes (AEMs) with various membrane structures were prepared by introducing various amines: trimethylamine (TMA), triethylamine (TEA), tri- n -propylamine (TPA) and tri- n -butylamine (TBA) into precursor membranes prepared from chloromethylstyrene (CMS)–divinylbenzene (DVB) and glycidyl methacrylate (GMA) – DVB. Their properties for ionic transport and anti-organic fouling were examined. Almost all of the prepared AEMs have excellent ionic transport properties: transport number of anions >0.94 and membrane resistance 2 . The voltage change through the AEMs during electrodialysis operation using solutions containing sodium dodecylbenzene-sulfonate as a foulant indicated that there are three cases of fouling mechanism being related to membrane structure: (a) aliphatic AEMs show lower fouling than aromatic ones; (b) the lower the water content of an AEM, the more remarkable the fouling; (c) the longer the chain length of the alkyl groups of the anion-exchange groups of an AEM, the more remarkable the fouling.

The cation-exchange membranes (CEMs) were prepared from a graft-copolymer consisting of a polysulfone (PSF) main chain and styrene sulfonic acid side chains. The graft-copolymer was synthesized by grafting ethyl p -styrenesulfonate (Etss) on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM) groups, changing Etss content in the polymers by using atom transfer radical polymerization. The PSF based-CEMs show almost the same mechanical strength as commercially available CEMs. The CEMs with CM content = 16.6 mol% have higher transport properties (dynamic state transport number = 0.98, membrane resistance = 1.5 Ω cm 2 ) than commercially-available CEMs.

Charge mosaic (CM) membranes with semi-interpenetrating network structures were prepared by blending poly(vinyl alcohol) as a membrane matrix, poly(allyl amine) as a polycation and poly(vinyl alcohol- co -2-acrylamido-2-methyl propane sulfonic acid) as a polyanion with varying polyelectrolyte contents under different cross-linking conditions. Our method can prepare CM membranes of a large area easily at low manufacture cost. Although the flux of electrolytes through the membrane is less than that through a typical charge mosaic membrane such as Desalton ® (Tosoh Co., Ltd.), which was prepared using micro-phase separation, the permselectivity for electrolytes through the CM membrane was more than 4 times higher than Desalton ® . These CM membranes have enough mechanical strength to form thin layer on a porous support membrane, thereby increasing the flux of electrolytes.

Braid-reinforced hollow fiber membranes with high mechanical properties and considerable antifouling surface were prepared by blending poly(vinyl chloride) (PVC) with poly(vinyl chloride-co-poly(ethylene glycol) methyl ether methacrylate) (poly(VC-co-PEGMA)) copolymer via non-solvent induced phase separation (NIPS). The tensile strength of the braid-reinforced PVC hollow fiber membranes were significantly larger than those of previously reported various types of PVC hollow fiber membranes. The high interfacial bonding strength indicated the good compatibility between the coating materials and the surface of polyethylene terephthalate (PET)-braid. Owing to the surface segregation phenomena, the membrane surface PEGMA coverage increased upon increasing the poly(VC-co-PEGMA)/PVC blending ratio, resulting in higher hydrophilicities and bovine serum albumin (BSA) repulsion. To compare the fouling properties, membranes with similar PWPs were prepared by adjusting the dope solution composition to eliminate the effect of hydrodynamic conditions on the membrane fouling performance. The blend membranes surface exhibited considerable fouling resistance to the molecular adsorption from both BSA solution and activated sludge solution. In both cases, the flux recovered to almost 80% of the initial flux using only water backflush. Considering their great mechanical properties and antifouling resistance to activated sludge solution, these novel membranes show good potential for application in wastewater treatment.

Poly(vinylidene fluoride) (PVDF) was blended with a new amphiphilic copolymer, poly(tetrafluoroethylene-co-vinyl alcohol) [poly(TFE-VA)], via non-solvent induced phase separation (NIPS) method to make membranes with superior antifouling properties. The effects of the VA/TFE segment ratio of the copolymer and the copolymer/PVDF blend ratio on the properties of the prepared membranes were studied. Membranes with similar water permeabilities, surface pore sizes, and rejection properties were prepared and used in bovine serum albumin (BSA) filtrations with the same initial water flux and almost the same operating pressure, to evaluate the sole effect of membrane material on fouling propensity. While the VA/TFE segment ratio strongly affected the membrane antifouling properties, the effects of the copolymer/PVDF blending ratio were not so drastic. Membrane surface hydrophilicity increased, and BSA adsorption and fouling decreased upon blending a small amount of amphiphilic copolymer with a high VA/TFE segment ratio with PVDF (copolymer/PVDF blending ratio 1:5). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43780.

A soluble and stable one-handed helical conjugated polymer without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer having two hydroxyl groups followed by desubstitution of the chiral groups in a solid membrane state . The reason for the success was the polymer reaction was carried out in the membrane state. This is an alternative method to obtain such a unique chiral polymer which was obtained only by the helix-sense-selective polymerization (HSSP) we reported before. In addition the efficiency of the chiral induction was higher than that of the HSSP. It is interesting that the “ Membrane state” acted like as if a protecting group.

A soluble and stable one-handed helical poly(substituted phenylacetylene) without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1) removing the chiral groups (desubstitution), and (2) introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution). The starting chiral monomer should have four characteristic substituents: (i) a chiral group bonded to an easily hydrolyzed spacer group, (ii) two hydroxyl groups, (iii) a long rigid hydrophobic spacer between the chiral group and the polymerizing group, (iv) a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300)/ε) for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.

Cage octasilsesquioxane with various substituents were obtained by the condensation reaction of various all- cis cyclic tetrasiloxanetetraol (R-T 4 -tetraol, R = phenyl, p -tolyl, i -butyl, naphthyl) with benzyltrimethylammonium hydroxide or tetrabutylammonium fluoride as a catalyst. Co-condensation of phenyl-T 4 -tetraol with phenyl- d 5 -T 4 -tetraol or with p -tolyl-T 4 -tetraol were found to proceed through reshuffling process evidenced by scrambling of the substituents. Pure octa(4-bromo-substituted phenyl)octasilsesquioxane was synthesized for the first time from tetra(4-bromo-substituted phenyl)tetrasiloxanetetraol sodium salt.

[(2-Methylpropyl)hydroxysilyl]-bridged double-decker silsesquioxane was synthesized, and its stereoisomers were obtained by fractional precipitation followed by silica gel column chromatography, and their structures were confirmed by 1H and 29Si NMR and single crystal X-RD. The pure cis, trans and mix isomer were polymerized with silane-terminated octamethyltetrasiloxane via cross-dehydrocoupling polycondensation catalyzed by tris(pentafluorophenyl)borane to give completely alternating structure of the double decker silsesquioxane, and linear octamethyltetrasiloxane. All the polymers showed significantly increased glass transition temperature, compared with linear poly(dimethylsiloxane). Excellently transparent organo-soluble polymers gave self-supporting film by simple casting method.

Various optically active silicon compounds have been synthesized or separated, and used to synthesize silicon-containing polymers with well-controlled stereochemical structures. Hydrosilylation, anionic ring-opening polymerization and cross-coupling reactions have been used to synthesize optically active and/or stereoregular silicon-containing polymers. Copyright © 2009 Society of Chemical Industry

Polymerization of 1-methyl-1-(1-naphthyl)-2,3-benzosilacyclobut-2-ene as a monomer by n-butyllithium and diphenylmethylsilyllithium gave polymers with reasonably well controlled molecular weight. Polymers from the (+)-monomer by these organolithium compounds were optically active with similar optical rotations, but with rather low stereoregularity. Ring-opening reactions of the compound by n-butyllithium and diphenylmethylsilyllithium, and that by benzyllithium as a model propagation reaction, too was regiospecific. However, all of these ring-opening reactions of the (+)-monomer did not proceed stereoselectively as anticipated. Stereoselectivity of the ring-opening reaction to give dimer was low, which suggested that the ring-opening reaction in the propagation step was also low.

Stereoregular and optically active polycarbosilanes were synthesized by polyaddition of optically active allylsilane and propargylsilane, and ring-opening polymerization of optically pure benzosilacyclobutene. Polyaddition of allylsilane gave an isotactic polymer, but chirality at the silicon center was lost in the polymer and the polymer became optically inactive. Propargylsilane, having a triple bond, can maintain double-bond and single-bond carbons attached to silicon atom even after polyaddition by hydrosilylation, and the formed polymer showed optical activity. Catalytic ring-opening polymerization of an optically pure benzosilacyclobutene gave an optically active polymer with high stereoregularity with well-controlled molecular weight by using triethylsilane as a chain-transfer agent.

A new polymer prepared by polymerization of 3,5-bis(hydroxymethyl)phenylacetylene having a chiral menthyl group via a very long and rigid spacer by an achiral rhodium complex with triethylamine as ...

Polymer electrolyte membranes (PEMs) for direct methanol fuel cell (DMFC) applications were prepared from a graft-copolymer (PSF-g-PSSA) consisting of a polysulfone (PSF) main chain and poly(styrene sulfonic acid) (PSSA) side chains with various average distances between side chains (Lav) and side chain lengths (Lsc). The polymers were synthesized by grafting ethyl p-styrenesulfonate (EtSS) on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM) groups, and by changing EtSS content in the copolymers by using atom transfer radical polymerization (ATRP). The DMFC performance tests using membrane electrode assemblis (MEAs) with the three types of the PEMs revealed that: a PSF-g-PSSA PEM (SF-6) prepared from a graft copolymer with short average distances between side chains (Lav) and medium Lsc had higher DMFC performance than PEMs with long Lav and long Lsc or with short Lav and short Lsc. SF-6 had about two times higher PDmax (68.4 mW/cm2) than Nafion® 112 at 30 wt % of methanol concentration. Furthermore, it had 58.2 mW/cm2 of PDmax at 50 wt % of methanol concentration because of it has the highest proton selectivity during DMFC operation of all the PSF-g-PSSA PEMs and Nafion® 112.

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively.

Features of the formation of cage oligomeric silsesquioxanes, including several new compounds, are described and possible reaction mechanism is proposed. Synthesis of phenyl oligomeric silsesquioxanes selectively functionalized at the 4-position is reported. Formation and utilization of incompletely condensed oligomeric silsesquioxanes are also described.

Hydrolysis of trialkoxysilanes having various substituents gave cyclic tetrasiloxanetetraols with all-cis isomer as the major fraction in the presence of equimolar amounts of water and sodium hydro...

Pseudo helix-sense-selective polymerisation of a wide range of achiral substituted acetylenes having dynamic covalent bonds has been realised to yield static one-handed helical polymers without any other chiral moieties.