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A polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) micellar structure with a P2VP core containing 5 nm CdS nanoparticles (NPs) and a PS shell formed in toluene that is a good solvent for PS block undergoes the core-shell inversion by excess addition of methanol that is a good solvent for P2VP block. It leads to the formation of micellar shell-embedded CdS NPs in the methanol major phase. The spontaneous crystalline growth of Au NPs on the CdS surfaces positioned at micellar shells without a further reduction process is newly demonstrated. The nanostructure of Au/CdS/PS-b-P2VP hybrid NPs is confirmed by transmission electron microscopy, energy-dispersive X-ray, and UV-Vis absorption.

INTRODUCTION Direct methanol fuel cells (DMFC) have received considerable attention because of their potential to replace current portable power sources. However, an important part of DMFC, proton exchange membranes (PEM), is not favorable for their practical applications. Perfluorosulfonic acid membranes such as Nafion, Aciplex, and Flemion are the most commonly used PEM in DMFC. However, even though they have excellent proton conductivity, mechanical strength, and electrochemical stability, they have several drawbacks such as high costs, a poor performance at high temperature, and a high methanol crossover.

A new methodology is successfully used for the concurrent synthesis of three different copolymers; diblock, triblock, and three-armed star-block copolymers of styrene and isoprene via the living anionic polymerization with control over the molecular weight and weight fractions of each block. The room temperature polymerization process has resulted in the well defined linear and radial block copolymers, when the living di-block of poly(styrene-b-isoprene) was coupled using cheap and readily available malonyl chloride as a novel coupling agent giving nearly 100% yield. The resulting block copolymers have narrow polydispersity index (PDI = 1.01–1.09) with a good agreement between the calculated and the observed molecular weights. The results are further supported by fractionation of the block copolymers by reversed-phase temperature gradient interaction chromatography (RP-TGIC) technique followed by size exclusion chromatography (SEC). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2636–2641, 2010

This paper demonstrates the optimization of proton conductivity and water uptake for cross-linkable polymer electrolytes through synthesis and characterization of end-group cross-linkable sulfonated poly(arylene ether) copolymers. The extent of reaction of cross-linking was controlled by reaction time resulting in a series of polymers with two, independent tunable parameters, degree of sulfonation (DS) and degree of cross-linking (DC). For the polymers presented, cross-linking improved proton conductivity while reducing water uptake, an uncommon trend in polymer electrolytes where water is critical for proton conduction. Other trends relating to changes are reported and the results yield insight into the role of DS and DC and how to optimize electrochemical properties and performance of polymer electrolytes through these tunable parameters. Select polymer electrolytes were tested in fuel cells where performance and durability with accelerated relative humidity cycling were compared with Nafion ® .

Side chain crosslinked (C-SFPEx-CMy) sulfonated poly(arylene ether) (SPAE) membranes containing fluorine moiety with varying degree of sulfonation (DS) were prepared and evaluated for use as a thin-film composite membrane for seawater desalination. C-SFPEx-CMy membranes were obtained by covalent crosslinking among ethynyl groups at the polymer side chain through thermal curing. The crosslinked network structure suppressed the water uptake and swelling ratio. A novel type of composite membranes (TC-SFPEx-CMy) were prepared side chain crosslinked SPAE layer containing fluorine moiety on top of PET non-woven with epoxy resin as bonding agent. TC-SFPEx-CMy show the increase in NaCl rejection as DS decreases from 30% to 70%. NaCl rejection of the membranes increased with increasing corsslinking moiety (CM) while water permeability decreases due to the crosslinked net work structure. Particularly, crosslinked membrane of 30 mol % of CM could enhance the salt (NaCl) rejection property up to 85.3 % as compared to...

A novel composite membrane for potential desalination was prepared by coating of sulfonated poly(arylene ether) on the non-woven web. The non-woven web was made of end-group crosslinkable flurorinated poly(arylene ether) nanowires fabricated by electrospinning method. The crosslinked non-woven web was obtained by covalent crosslinking among ethynyl groups at the polymer chain end via thermal curing. The salt rejection and permeability of the crosslinked nonwoven web were controlled by varying degrees of sulfonation (DS) of sulfonated poly(arylene ether). The compostie membranes show the increase of NaCl rejection as DS decreases from 20% to 60%, while water permeability decreases due to the increase of hydrophilicity. The order of salt rejection was as follows: Na2SO4 (88.4%), NaCl (79.3%), MgSO4 (70.2%), Mg2Cl2 (62.3%).

Fluorinated poly(arylene ether sulfide) (FPAESI) and ethynyl-terminated fluorinated poly(arylene ether sulfide) (E-FPAESI) were synthesized via step-growth polymerization from prepared dihydroxy monomer and pentafluorophenylsulfide, then E-FPAESI was followed by a reaction with 3-ethynylphenol. The number-average molecular weights and polydispersities of FPAESI and E-FPAESI were in the range of 12,000–26,000 and 1.75–3.18, respectively. The glass transition temperatures of the polymers varied from 138 to 178 °C depending on the molecular weight of the polymer used and were changed to the range of 191–245 °C after curing. The FPAESIs and E-FPAESIs exhibited high thermal stability up to 445–450 °C and 457–462 °C, respectively. The refractive index and birefringence of spin-coated polymer films were determined by the prism-coupling method. The refractive indices and birefringences of the films were in the range of 1.5849–1.5880 and 0.0014–0.0035 at a 1550 nm wavelength, respectively. The effect of E-FPAESI structure on the birefringence is compared with various reported poly(arylene ether sulfide)s.

An isopropyl myristate (IPM) biocompatible oil and an IPM solution of dodecanethiol-capped Ag nanoparticles (NPs, 4.5 nm) were used as hydrophobes to suppress the Ostwald ripening of monomer/hydrophobe miniemulsified droplets in a surfactant-stabilized water phase. The formation of non-IPM-encapsulated nanospheres (48 nm) and IPM-encapsulated nanocapsules (90 nm) were precisely controlled by using a water-soluble and an oil-soluble initiator, respectively, in the presence of a pure IPM as a hydrophobe in miniemulsion polymerization. Well-defined PS nanospheres, on which surfaces were coated with Ag NPs (Ag/PS nanospheres, 65 nm), and nanocapsules encapsulating both NPs and IPM liquid phase (Ag-IPM/PS nanocapsules, 115 nm) were made by replacing the hydrophobe from pure IPM with Ag/IPM solution. These nanostructures were characterized by transmission and scanning electron microscopes.

Crosslinkable sulfonated poly(arylene ether ketone) copolymers with various degrees of sulfonation (DS) were prepared and evaluated for use as proton exchange membranes (PEM). The copolymers were synthesized via step growth polymerization using 2,8-dihydroxynaphthalene-6-sulfonated salt (2,8-DHNS-6), 4,4′-(hexafluoroisopropylidene) diphenol (6F-BPA), 4,4′-biphenol (BP), and 4,4′-difluorobenzophenone (DFBP). 1 H NMR and FTIR-ATR spectra confirmed the structure of the copolymers and were also used to determine the obtained DS values of the copolymers. Crosslinked membranes were obtained by thermal curing of the crosslinkable copolymers. The membranes formed a crosslinking network structure via covalent bonding. The glass transition temperatures ( T g ) of the crosslinked membranes were determined by differential scanning calorimetry (DSC) and ranged from 208 to 258 °C. The decomposition temperatures ( T d ) of the membranes ranged from 309 to 325 °C for acid forms. The resulting membranes were characterized via an evaluation of their essential membrane properties, such as ion exchange capacity (IEC), water uptake, and proton conductivity. The performance of the membranes was found to be dependent on the DS and IEC.

This review highlights the precise synthesis and application of various well-defined rod–coil and coil–coil block copolymers composed of poly(2-(or 4-)vinylpyridine) (P2VP or P4VP) block(s) with pyridine moieties. These polymers were synthesized by means of living anionic polymerization. Poly(hexyl isocyanate) (PHIC) was used as the rod-like segment, because hexyl isocyanate undergoes living anionic polymerization under carefully selected conditions. This review describes the syntheses of the block copolymers, polystyrene-b-P2VP, polystyrene-b-P4VP, polyisoprene-b-P2VP, P2VP-b-poly(methyl methacrylate), P2VP-b-poly(ethylene oxide), P2VP-b-poly(2-(N-carbazolyl)ethyl methacrylate), P2VP-b-PHIC, P2VP-b-PHIC-b-P2VP, and PHIC-b-P2VP-b-PHIC. The formation of self-organized nanostructured materials and molecular assemblies by such block copolymers and their possible applications are also described. These assemblies include monolayers, microphase-separated periodic-ordered nanostructures, micelles, polymer–metal complexes, nanoparticles, inorganic and metal layers, and nanoporous films with nanoparticles.

CdS nanoparticles of 4.5 nm diameter were synthesized in poly(2-vinylpyridine) micellar cores which were obtained by solvating a polystyrene-block-poly(2-vinylpyridine) block copolymer in polystyrene-selective toluene. Then, a C 60 -toluene solution was dispersed into the CdS micelle solution with stirring. This led to the well-defined organization of two different nanoparticles; specifically: a CdS NP decorated by several/dozens of C 60 molecules, because C 60 molecules were strongly coordinated with pyridine molecules in the micellar cores by charge-transfer complexation C δ― 60 ―P2VP δ+ . A harmoniously organized CdS/ C 60 micellar structure was clearly verified by transmission electron microscopy. Fluorescent quenching of CdS nanoparticles, which was strongly affected by neighboring C 60 molecules, was observed.

Anionic polymerization of n-alkoxycarbonylaminohexyl isocyanates was carried out using a sodium benzanilide (Na-BA) as an initiator without additives in tetrahydrofuran (THF) at ―98 °C under high vacuum (10 ―6 Torr). The polymerization of methoxycarbonylaminohexyl isocyanate (MAHI) resulted in an insoluble material. However, the polymerization of n-propyloxycarbonylaminohexyl isocyanate (PAHI) with propyl side chain was moderately controlled and gave high yields (∼98%) of the polymers with polydispersity index (PDI 1.18―1.22). The results of the polymerization were improved significantly when n-pentanoxycarbonylaminohexyl isocyanate (PEAHI) with pentyl side chain was used. Poly(n-pentanoxycarbonylaminohexyl isocyanate) (PPEAHI) was isolated in ∼99% yields, controlled molecular weight, and a narrow PDI (1.08―1.14). The living nature of PPEAHI was indicated from the linear plot of the molar ratio of the monomer to the initiator versus the number-average molecular weight (M n ) in addition to the successful block copolymerization of PEAHI with another isocyanate monomer, n-hexyl isocyanate (HIC). Furthermore, the hydrogen bonding between the active hydrogen of the carbamate group of the PPEAHI and the nitrogen atom of the poly(2-vinylpyridine) formed a vesicle-like morphology in methanol.

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

End-group cross-linkable sulfonated poly(arylene ether) polymer (E-SFQK) was synthesized via direct polymerization of potassium 2,5-dihydroxybenzenesulfonate (SHQ) and decafluorobiphenyl (DFBP), followed by a reaction with ethynylphenol (EP). The cross-linking reaction of the ethynyl end group of E-SFQK was performed at 250 °C. After cross-linking, proton conductivity, water uptake, and swelling ratio of cross-linked membrane decreased from 0.16 (noncross-linked membrane) to 0.13 S/cm, from 86% to 42%, and from 31% to 13%, respectively. The effect of cross-linking time on proton conductivity, water uptake, and swelling ratio were also investigated. Methanol permeability of cross-linked membrane was compared with Nafion 117 due to solubility of noncross-linked membranes in methanol. The cross-linked membrane performed better, with a methanol permeability of 88 × 10−8 cm2/s, as compared with 154 × 10−8 cm2/s for Nafion 117. The cross-linked membrane also exhibited improved chemical resistance and oxidative ...

Novel sulfonated poly(arylene ether) copolymers containing cross-linking moiety and fluorine atoms were prepared for proton exchange membranes of fuel cells. The copolymers were synthesized using potassium 2,5-dihydroxybenzenesulfonate (SHQ), 4,4′-(hexafluoroisopropylidene)diphenol (6F-BPA), decafluorobiphenyl (DFBP), and 1-ethynyl-2,4-difluorobenzeneand (CM) as a cross-linking moiety through polycondensation. The chemical structures of the cross-linkable copolymers were analyzed by 1H NMR, 19F NMR, and FTIR-ATR spectra. Cross-linked membranes are obtained by thermal curing of the cross-linkable copolymers. The thermal properties of the cross-linked membranes were characterized by TGA and DSC. Intrinsic viscosity and gel fraction were also evaluated in order to measure the molecular weight and cross-linking density, respectively. The cross-linked network structure greatly suppressed the water uptake and swelling of the cross-linked membrane. The proton conductivity and methanol permeability of the membran...

Unimolecular rectification behavior of a known amphiphilic fullerene derivative, 1,4,11,15,30-pentakis(4-hydroxyphenyl)-2 H -1,2,4,11,15,30-hexahydro-[60]fullerene, (4-HOC 6 H 4 ) 5 HC 60 (referred to here as the fullerene pentapod), is reported. The HOMO and LUMO energy levels of the pentapod were determined by density functional theory calculations (B3LYP/6-31G ∗∗ ). It was found that the HOMO of the donor moiety and the LUMO of the acceptor are in the same fullerene cage, quite unlike the fullerene derivatives so far reported as molecular rectifiers. The molecule formed a stable Langmuir-Blodgett film at the air–water interface. Characterization of the film indicated that it constitutes mostly a monolayer of molecules with the hydrophobic C 60 moiety pointing upwards. The LB film was transferred over Au(1 1 1) substrate and electrical conductivity of the film was measured by conducting atomic force microscopy. An asymmetric electrical rectification behavior was observed in the voltage range of ±1.0 V to ±2.0 V. Beyond a bias voltage of ±2.0 V, rectification ratio decreased steadily, until at ±2.5 V the current–voltage curve became symmetric. The observed electrical rectification behavior was ascribed to resonant electron tunneling between the Fermi level of the electrode and the molecular orbital levels of the fullerene pentapod. Charge transport in the preferred direction under a suitable applied bias was facilitated due to efficient electronic interactions of the molecular orbitals through a combined effect of homo- and peri-conjugation. This constitutes a new class of donor–acceptor system and a step forward in the field of molecular electronics.

A TiO 2 film was modified by adding light scattering particles and applied to an anode electrode in solid-state dye-sensitized solar cells (DSSCs). The TiO 2 films with 10 wt% (vs. TiO 2 weight) light scattering particles showed enhanced performance (28%), compared with nanocrystalline TiO 2 films, which were used as the controls. In particular, the photocurrent density ( J sc ) reached approximately 12.6 mA/cm 2 under a one-sun condition. This was attributed to the light scattering effect and decrease in internal resistance through the macroporous structure with a minor loss of electron transport. However, in the case of a larger concentration of light scattering particles (>10 wt%), there was a decrease in the efficiency of DSSCs, which resulted from the decreased surface area and degraded electron transport and charge recombination properties, as confirmed by the measurement of stepped light-induced photocurrent and photovoltage transients. Furthermore, the diffusion properties and kinetics of the composite polymer electrolyte with the nanoporous and macroporous TiO 2 films were compared and evaluated from the electrochemical impedance spectra.

Partially fluorinated poly(arylene ether) copolymer having reactive functional group are used to fabricate the MEA to improve the interfacial adhesion between membrane and electrode. The optimum MEA processing procedure was studied using different hot pressing temperature and crosslinking. Good interfacial adhesion between hydrocarbon membrane and Nafion bonded electrode produced excellent fuel cell performance which was comparable to the MEA using Nafion 212.

Coupling of the living poly(n-hexyl isocyanate) (PHIC) with malonyl chloride in the presence of pyridine resulted in a well-defined polymer PHIC-COCH 2 CO-PHIC in ∼95% yields. The active methylene group in the center of the polymer is a site for the introduction of suitable functionalities so as to impart additional attributes to the polymer. Poly(ethylene glycol) was anchored to the polymer center using monomethacrylate poly(ethylene glycol) (PEG1) by Michael addition reaction leading to the amphiphilc copolymer (PHIC) 2 -PEG1. Two molecules of PHIC-COCH 2 CO-PHIC were linked with a dimethacrylate poly(ethylene glycol) (PEG2) leading to (PHIC)2-PEG2-(PHIC)2. These miktoarm star copolymers of A 2 B and A 2 BA 2 architecture, where A is the hydrophobic PHIC and B is the hydrophilic and biocompatible PEG, were isolated in ∼90% yields with controlled molecular weight and narrow molecular weight distribution (1.08-1.14). The amphiphilic A 2 B-type copolymers formed solid micelles in CHCl 3 and vesicles in THF:C 2 H 5 OH (1:9 v/v) mixed solvent.

Nanoscale metal patterns were successfully reproduced on top of a functional organic layer by a direct metal-transfer technique (DMT). A gold film deposited on the protruding features of a stamp was transferred to the organic layer by controlling its stickiness through a two-step thermal treatment. The process was also suitable for the transfer of highly adhesive metal materials to the stamp surface by using an additional gold layer. Chromium nanowires at 70 nm half-pitch were faithfully produced without any damage to the organic active layer.

A series of new covalent organic/inorganic hybrid proton-conductive membranes, each with a semi-interpenetrating polymer network (semi-IPN), for direct methanol fuel cell (DMFC) applications is prepared through the following sequence: (i) copolymerization of impregnated styrene (St), p -vinylbenzyl chloride (VBC) and divinylbenzene (DVB) within a supporting polyvinyl chloride (PVC) film; (ii) reaction of the chloromethyl group with 3-(methylamine)propyl-trimethoxysilane (MAPTMS); (ii) a sol–gel process under acidic conditions; (iv) a sulfonation reaction. The developed membranes are characterized in terms of Fourier transform infrared/attenuated total reflectance (FTIR/ATR), scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDXA), elemental analysis (EA) and thermogravimetric analysis (TGA), which confirm the formation of the target membranes. The developed copolymer chains are interpenetrating with the PVC matrix to form the semi-IPN structure, and the inorganic silica is covalently bound to the copolymers. These features provide the membranes with high mechanical strength. The effect of silica content is investigated. As the silica content increases, proton conductivity and water content decrease, whereas oxidative stability is improved. In particular, methanol permeability and methanol uptake are reduced largely by the silica. The ratio of proton conductivity to methanol permeability for the hybrid membranes is higher than that of Nafion 117. All these properties make the hybrid membranes a potential candidate for DMFC applications.

We report that the amphiphilic rod−coil−rod triblock copolymer with a coil attractive to the substrate surface self-organize into liquid crystalline monolayers or bilayers of a few nanometers thickness on the substrate surface. The copolymer investigated is a triblock copolymer, poly(n-hexyl isocyanate-b-2-vinylpyridine-b-n-hexyl isocyanate) (PHIC-b-P2VP-b-PHIC). Key processes of self-organization in the thin films, such as adsorption, desorption, diffusion, nematic and smectic ordering, and microphase separation, are tuned by exposing dip- or immersion-coated nanoscale films to the vapor of solvents which are rod (PHIC)-selective, coil (P2VP)-selective, or good to both blocks. Reorganization of the rod−coils in the nanofilms yielded various morphologies in the monolayer or bilayer, including unique long-range-ordered, smectic-on-nematic biphasic sheets. The results offer understanding on the complex morphological evolution in amphiphilic rod−coil block copolymers on the substrate surface.

As a novel class of proton exchange membrane (PEM) materials for application in fuel cells, sulfonated poly(arylene ether ketone)s (SPAEK-BPs) were prepared by polycondensation via a nucleophilic substitution reaction followed by post-sulfonation. In this way, SPAEK-BPs with different degrees of sulfonation (DS) were quantitatively synthesized via the use of chlorosulfonic acid as the sulfonating agent. It was discovered that only one sulfonic acid group can be selectively introduced without degradation per each repeating unit of polymer due to requirements for controlling reaction conditions such as reaction time and temperature. In this study, the experimentally observed DS were close to the theoretical values expected from the monomer ratios. The glass transition temperatures ( T g 's) and decomposition temperatures ( T d 's) of the polymers varied from 167 to 213 and 298 to 343 °C, respectively. In addition, the proton conductivities of the SPAEK-BP membranes exhibited up to a maximum of about 0.083 S/cm at 25 °C and 0.098 S/cm at 80 °C.

The sulfonated polystyrene (SPSt)/polyvinyl chloride (PVC) composite electrolyte membranes were prepared via styrene-impregnated polymerization within PVC matrix and subsequent sulfonation. The propagated polystyrene chains were interpenetrated with those of the PVC film, and hence the two components were completely compatible. The effects of some preparation parameters, including monomer solution composition, polymerization and sulfonation conditions, on membrane performance were investigated. It was found that crosslinking with DVB improved oxidative stability, while excess crosslinking might lead to decrease in the proton conductivity. Polymerization should be carried out at 80 °C for more than 8 h; otherwise the produced polystyrene had relatively low molecular weight and might leach out of the membrane. The higher concentration of chlorosulfonic acid or the higher sulfonation temperature caused side reactions, which led to decrease in proton conductivity as well as slight improvement in oxidative stability. Furthermore, repetitious polymerization under hot-pressing plates further improved proton conductivity with slight increase in membrane thickness. Preliminary data in single cell test showed that the prepared membrane had comparable performance with commercial Nafion. This study demonstrates that an inexpensive polymer electrolyte membrane suitable for low-temperature PEMFC applications can be prepared easily by styrene/DVB-impregnated polymerization within PVC substrate with subsequent sulfonation in chlorosulfonic acid.

A facile approach to synthesis of a series of coil−rod−coil triblock copolymers by in situ coupling of living diblock copolymers is reported. The living diblock copolymer poly(2-vinylpyridine)-block-poly(n-hexyl isocyanate) (P2VP-b-PHIC) synthesized by anionic polymerization was coupled using malonyl chloride or suberoyl chloride in the presence of pyridine. The triblock copolymers were obtained in ∼94−99% yields without the need for fractionation or separation. The copolymers showed narrow molecular weight distribution (MWD = 1.08−1.14) and good agreement between the calculated and observed molecular weights. In a solvent such as tetrahydrofuran (THF), which is common to both the blocks, the copolymers showed characteristics of microphase separation. With high rod volume fractions lamellar phase separation with long-range order was observed.

The amphiphilic monomer 2-(4-vinylphenyl)pyridine (VPPy) has been successfully polymerized using a complex of sec-butyllithium (s-BuLi) with lithium chloride (LiCl) and coordination of VPPy with LiCl at −45 °C for 72 h without side reactions such as cross-linking and branching. However, it takes 3 days to complete the polymerization with 100% yield, and the polydispersity index (Mw/Mn = 1.15) was relatively broad. In contrast, the anionic polymerization using diphenylmethyl potassium (DPM-K) as the weak initiator was more feasible. The yield of the polymer reached 100% within 150 min at −78 °C, which significantly reduced polymerization time with a narrow molecular weight distribution below 1.1. To investigate their living nature and reactivity, the block copolymerization of VPPy with styrene, isoprene, 2-vinylpyridine, and methyl methacrylate were carried out by sequential anionic polymerizations without additives such as LiCl and Et2Zn. The resulting block copolymers of PVPPy-b-PMMA in tetrahydrofuran s...

Micellar core-embedded Au or CdS nanoparticles (NPs), in which the number of NPs was controlled by a solid type or a solution type of metallic precursors and by their amounts, were constructed using a block copolymer as a template. The location of NPs located at the micellar core was dramatically changed to the corona by the solvent-induced micellar core-corona inversion. By mixing the synthetic methods demonstrated, harmonious Au/CdS NPs with different particle sizes, numbers, and positions in the micellar core were also prepared.

Azobenzene functionalized polyisocyanate and cyclic trimer with the same chemical composition were synthesized via anionic living polymerization. Thin films were prepared through a simple spin coating process, especially even with low molecular weight of trimer, it was possible to form optically transparent films. Photoinduced phenomena of dichroism, birefringence and holographic surface relief grating formation were investigated in relation to their molecular structures by irradiation of Ar ion laser beam. Compared to the azo polymer, generally the cyclic trimer showed faster growth rate of birefringence and increased diffraction efficiency during holographic surface grating formation, due to the absence of long polymer backbones and the lack of their complicated entanglements, but the final saturated values were smaller. The efficient surface relief grating formation was confirmed from the AFM images, which showed regularly defined sinusoidal relief structures.

The distinct polymeric nanocapsule hybrid-structures consisting of LCs in the core and PMMA or polystyrene in the corona domain were prepared by one-step miniemulsion polymerization. Nematic LCs (4'-pentyl-4-biphenylcarbonitrile and 4′-heptyloxy-4-biphenylcarbonitrile) were especially adopted as hydrophobes that can suppress Ostwald ripening and had an important role to stabilize the miniemulsion droplets and control the size distributions of the latexes. The polymeric nanocapsule structures with narrow size distributions were confirmed by TEM and DLS measurements.

Polymeric materials have unique properties, such as flexibility and easy processability via spin-coating, ink-jet printing, and roll-to-roll processing. Thus, polymer-based memory devices have received significant attention because of their many advantages, including low fabrication cost, good scalability, printability, simplicity of device structure, and three-dimensional stackability. Among polymeric materials, random polymers have been predominantly used for the development of several types of polymer-based memory device. This chapter describes non-volatile memory devices based on polymers containing electron-donating and/or accepting groups among various organic materials. Depending on the polymer structure, well-defined homopolymers, rod–coil block copolymers, and coil–coil block copolymers have been categorized, and various memory devices have been fabricated using each polymer; these devices showed biswitching behavior. The different performances of the devices have also been demonstrated using different electrodes and some additives.

The use of a PtAu catalyst as an anode catalyst for the oxidation of formic acid in direct formic acid fuel cells is described. Catalytic activities of PtAu and PtRu anodes were studied using a linear sweep voltammetry technique in a single cell configuration. PtAu showed a lower on-set potential and a larger current density than that of PtRu in formic acid oxidation. In addition, the maximum power densities at 30 °C for PtAu and PtRu were 94 and 74 mW cm−2, respectively. In order to evaluate long-term durability, the single cells were operated for hundreds of hours with a 6 M aqueous formic acid solution at 60 °C under 100 mA cm−2. The difference in performance between PtAu and PtRu after 500 h reached ca. 90 mV in direct formic acid fuel cells.

A strategy for the synthesis of sol-gel hybrid materials that contain perfluorocyclobutyl groups is reported. Sol-gel films have been prepared from three types of siloxane monomers using a typical sol-gel method in an acidic atmosphere, followed by UV irradiation and dimerization. The materials show high thermal stability that exceeds 400 °C. At a wavelength of 1 550 nm, the refractive index, the bire-fringence, and the optical loss of the sol-gel materials are found to be in the ranges of 1.4368-1.4876, -0.0003-0.0029, and 0.34-0.45 dB · cm -1 , respectively.

Ethynyl-terminated fluorinated poly(arylene ether sulfide) (E-FPAESI) was synthesized via nucleophilic aromatic substitution from dihydroxy monomer and pentafluorophenyl sulfide, followed by the reaction with 3-ethynylphenol. Dihydroxy monomer was synthesized in four steps via bromination, Grignard, Suzuki cross-coupling, and demethylation techniques. The number-average molecular weights and polydispersities of the E-FPAESI were in the ranges of 7700−23 000 and 1.53−2.89, respectively. The glass transition temperatures of the polymers varied from 126 to 171 °C and upon curing in the range of 168−236 °C. E-FPAESI exhibited high thermal stability up to 451−483 °C. The refractive indices and birefringences of the spin-coated polymer films were in the ranges of 1.4943−1.5047 and 0.0004−0.0009 at 1550 nm wavelength, respectively. The optical loss for E-FPAESI was about 0.45 dB/cm at 1550 nm wavelength.

The synthesis of new isocyanate monomers and their polymerization by anionic route is reported. Reaction of 1,6-diisocyanatohexane with aliphatic alcohols such as methanol, n-propanol and n-pentanol in 1:0.5 molar ratios was carried out in the presence of pyridine such that one -NCO group remained unreacted. The anionic polymerization of n-alkoxycarbonylaminohexyl isocyanates was carried out using sodium napthalenide (Na-Naph) initiator in the presence of 15-crown-5 (15C5) and sodium tetraphenylborate as the additives. While polymerization of n-propyloxy-carbonylaminohexyl isocyanate (PAHI) and n-pentanoxycarbonylaminohexyl isocyanate (PEAHI) was feasible that of methoxycarbonylaminohexyl isocyanate (MAHI) led to an insoluble material. The polymers were isolated in high yields with NaBPh 4 as the additive.

Rod−coil−rod triblock copolymers of 2-vinylpyridine (2VP) and n-hexyl isocyanate (HIC) were synthesized by living anionic polymerization. The homopolymerization of 2VP was carried out at −78 °C in THF by using bidirectional initiators sodium naphthalenide (Na−Naph) and potassium naphthalenide (K−Naph). Block copolymerization with HIC was performed at −98 °C in the presence of sodium tetraphenylborate additive. While K−Naph yields copolymers of broad molecular weight distribution, Na−Naph was quite effective in facilitating a high degree of control over the copolymerization. The block copolymers containing higher rod volume fraction showed lamellar microphase separation in THF, a common solvent for both the rod and the coil blocks. The self-organization of the copolymer in solvents selective for one block was quite fascinating in that in CHCl3 solid micelles of ∼20 nm were formed, whereas large hollow micelles of ∼200 nm were generated in CH3OH.

A new ABA-type triblock copolymer was synthesized by coupling reaction of anhydride and amine-functionalized telechelic polymers. The two blocks of the copolymer, polystyrene end-functionalized with anhydride group (PS-anh) and poly(arylene ether sulfone) functionalized with aromatic amine groups at the termini (PAES-amn), were synthesized by living anionic and condensation polymerization, respectively. The block copolymer was characterized by size exclusion chromatography (SEC), thermal (DSC and TGA) studies, and the morphology investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The microstructure of the block copolymer was affected by the volume fraction of the constituent blocks.

Saw dust-reinforced linear low density polyethylene (LLDPE) (1:1) composites were prepared by using ethylene-vinyl alcohol copolymer (EVAL) as adhesion promoter to improve mechanical strength. To evaluate the optimum vinylalcohol (VA) content in EVAL, various EVAL samples containing different contents of VA were used. The tensile properties of saw dust-LLDPE composites were improved by using EVAL as adhesion promoter in place of ethylene-vinyl acetate copolymer (EVAc). The saw dust-LLDPE composites prepared with EVAL containing 15 mol% VA showed the maximum yield stress and modulus. The tensile stress increased with addition of EVAL up to 3wt% on the wood filler, and then leveled off in the range of 3-10 wt%. However, the elongation was decreased with increasing VA content. Hydrogen bonding interaction between saw dust and EVAL was detected by FT-IR spectra. When EVAL consisting with 15 mol% VA was used, good adhesion between saw dust and LLDPE matrix was confirmed by SEM fractography.

Nanocomposites of PtRu nanoparticles and polyaniline (an electronically conducting polymer) were synthesized by the borohydride reduction method in an aqueous solution for the anode electrode in direct methanol fuel cells (DMFCs). Due to the high electronic conductivity of polyaniline, the methanol oxidation current for polyaniline supported PtRu nanocomposites was similar to that of carbon supported PtRu catalysts. In addition, Pd-impregnated nanocomposite Nafion membranes were suggested to enhance DMFC performance by blocking or reducing methanol crossover and their characteristics were affected by the impregnation time of Pd-nanoparticles.

Optical properties such as refractive index, birefringence, thermal stability, and optical loss of fluorinated co-poly(arylene ether sulfide)s and co-poly(arylene ether sulfone)s were investigated, and they are related to the molecular structure of the polymers. The refractive index of the optical polymers varies in the range of 1.51/spl sim/1.60, and its variation is well described by a Lorentz-Lorenz equation. Their birefringence varies between 0.0027/spl sim/0.0039 for the sulfides series and between 0.0009/spl sim/0.0025 for the sulfone series at a 1.55-/spl mu/m wavelength, respectively. The birefringence is analyzed based on the microscopic anisotropic ratio of the polarizability of the molecular repeating unit resulting in good linear relationship between them within the polymer groups. This result implies that the molecular calculation can be utilized to design polymers with low birefringence. The propagation losses of the optical polymers were 0.1/spl sim/0.3 and 0.2/spl sim/0.5 dB/cm at the wavelength of 1.3 and 1.55 /spl mu/m, respectively. The optical losses are inversely proportional to fluorine content. The polymers have good thermal stability upon long-term thermal stress at 100/spl deg/C for 1000 h and short-term thermal stress at 300/spl deg/C for 1 h.

A series of selectively sulfonated polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene copolymers (SSEBS) with varying degree of sulfonation were synthesized. The morphology of SSEBS characterized by AFM and TEM showed the microphase separated nano-structures. The SSEBS formed nano-sized ionic channels by association of the sulfonate groups in the styrene blocks of SEBS. The well-ordered ionic channels are continuously linked, which resulted in enhanced proton conductivity. Proton conductivity values of SSEBS determined by membrane electrical resistance (MER) measurement was more than that of the commercially available proton exchange membranes.

To study living anionic polymerization, 3-(triethylsilyl)propyl isocyanate (TEtSPI) monomer was synthesized by hydrosilylation of allylamine with triethylsilane and treatment of the resulting amine with triphosgene. The polymerization of TEtSPI was performed with sodium naphthalenide (Na-Naph) as an initiator and in the absence and presence of sodium tetraphenylborate (NaBPh4) as an additive in tetrahydrofuran (THF) at −78 and at −98 °C. A highly stabilized amidate anion for living polymerization of isocyanates was generated for the first time with the combined effect of the bulky substituent and the shielding action of the additive NaBPh4, extending the living character at least up to 120 min at −98 °C. Even the anion could exist at −78 °C for 10 min. A block copolymer, poly(n-hexyl isocyanate)-b-poly[(3-triethylsilyl)propyl isocyanate]-b-poly(n-hexyl isocyanate), was synthesized with quantitative yields and controlled molecular weights via living anionic polymerization in THF at −78 °C for TEtSPI and −98 °C for n-hexyl isocyanate, respectively, with Na-Naph with three times of NaBPh4 as a common ion salt. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 933–940, 2004

A well-defined amphiphilic coil-rod block copolymer, poly(2-vinyl pyridine)-b-poly(n-hexyl isocyanate) (P2VP-b-PHIC), was synthesized with quantitative yields by anionic polymerization. A low reactive one-directional initiator, potassium diphenyl methane (DPM-K), was very effective in polymerizing 2-vinyl pyridine (2VP) without side reactions, leading to perfect control over molecular weight and molecular weight distribution over a broad range of initiator and monomer concentration. Copolymerization of 2VP with n-hexyl isocyanate (HIC) was carried out in the presence of sodium tetraphenyl borate (NaBPh4) to prevent backbiting reactions during isocyanate polymerization. Terminating the living end with a suitable end-capping agent resulted in a P2VP-b-PHIC coil-rod block copolymer with controlled molecular weight and narrow molecular weight distribution. Cast film from a chloroform solution of P2VP-b-PHIC displayed microphase separation, characteristic of coil-rod block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 607–615, 2005

In this article, size reduction and wide impedance feeding techniques for antenna design are presented.An inductor connected with a main antenna element in series reduced a resonance frequency of the fundamental mode and a size reduction of about 33% was obtained. In addition, a shunt capacitor between the shorting and feed line enhanced the impedance bandwidth to fully cover the required impedance bandwidths of IEEE 802.11 b/g (2.4–2.484 GHz) and IEEE 802.11a (5.15–5.875 GHz) The proposed antenna possesses a very wide impedance bandwidth of 1957 MHz in the range of the 5 GHz band at a VSWR < 2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:850–852, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27411

We demonstrated nonvolatile 8 × 8 array organic memory devices utilizing a PC-interface memory cell tester. The organic memory devices composed of a Ag/poly(3-hexylthiophene-2,5-diyl) (P3HT)/p+ poly-Si structure exhibited excellent memory performance properties, including stable switching behavior, proper statistical distribution, and long retention time. We succeeded in independently addressing and reading the data in the memory cell array using the PC-interface memory cell tester, opening an avenue toward more realistic organic memory device applications.

A series of new chain-end-functionalized polystyrenes with two, four, and eight 1,3-butadienyl groups (PS(Bd) n, n = 2, 4, and 8) were synthesized by the reaction ofchain-end-functionalized polystyrenes with the same numbers of benzyl bromide moieties with the 1,1-diphenylalkyl anion prepared from oligo(α-methylstyryl)lithium and 1-[4-(4-methylene-5-hexenyl)phenyl]-1-phenylethylene. These 1,3-butadiene-functionalized polymers reacted efficiently with polystyryllithium (PSLi) to afford well-defined 3-, 5-, and 9-arm star-branched polystyrenes. A successive synthesis from (PS(Bd) 4 to 5-arm followed by 9-arm star-branched polystyrenes was demonstrated by twice repeating the reaction sequence involving the reaction of PSLi with (PS(Bd) 4 and subsequent in-situ introduction of 1,3-butadienyl groups via the generated anions. The terminal 1,3-butadienyl groups were quantitatively converted into highly reactive anhydride and epoxy functions by the Diels-Alder and epoxidation reactions, respectively. The resulting anhydride- and epoxy-functionalized polymers were successfully used as new polymeric coupling agents to synthesize well-defined star-branched polystyrenes.

Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly( N -vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH 3 OH/0.5 M H 2 SO 4 solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes.