SYNOPSISThe efficiency of thioxanthones and ketocoumarins as photoinitiators has been checked in visible laser light-induced polymerization reactions and discussed in terms of excited-state reactivity (as revealed by time-resolved laser spectroscopy). These compounds undergo fast electron transfer reactions in the presence of amines and onium salts. Transient absorption spectra and rate constants of the processes involved have been determined. The combination photoinitiator-amine-onium salt appears as very promising for the design of efficient photosensitive systems.

A series of diblock-copolymers were synthesized through anionic polymerization of styrene and tert-butyl methacrylate (tBuA) with different monomer ratios, and analogous block-copolymeric derivatives (PS-b-PAA)s with monofunctional carboxylic acid groups were obtained by further hydrolyzation as hydrogen-bonded (H-bonded) proton donors. Via H-bonded interaction, these diblock-coplymeric donors (PS-b-PAA)s were incorporated with luminescent mono-pyridyl/bis-pyridyl acceptors to form single/double H-bonded supramolecules, that is, H-bonded side-chain/crosslinking copolymers, respectively. The supramolecular architectures formed by donor polymers and light-emitting acceptors were influenced by the ratio of acid blocks in the diblock copolymeric donors and the type of single/double H-bonded light-emitting acceptors. Their thermal and luminescent properties can be adjusted by H-bonds, and more than 100 nm of red-shifted photoluminescence (PL) emissions were observed, which depend on the degrees of the H-bonding interactions. Self-assembled phenomena of amphiphilic dibolck copolymers and their H-bonded complexes were confirmed by TEM micrographs, and supramolecular microphase separation of spherical micelle-like morphology was demonstrated to affect the photophysical properties. Polymer light-emitting diode (PLED) devices containing H-bonded complexes showed electroluminescence (EL) emissions of 503-560 nm under turn-on voltages of 7.5-9.0 V, maximum power efficiencies of 0.23-0.37 cd/A (at 100 mA/cm 2 ), and maximum luminances of 318-519 cd/m 2 (around 25 V). V V C 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: [4685][4686][4687][4688][4689][4690][4691][4692][4693][4694][4695][4696][4697][4698][4699][4700][4701][4702] 2009

The recent oil resource shortage has prompted the development of the proton exchange membrane fuel cell (PEMFC) system. PEMFC is a possible source of power that can be used in aircraft, household electricity, agriculture, fishing, motor vehicles, ships, submarines, bicycles, and other portable power systems in the future. This paper emphasizes the production of lightweight bipolar plates to solve several existing problems in the PEMFC system, including weight, cost, and integration. Conventional bipolar plates account for approximately 90% of the weight of battery packs. Therefore, an injection molded flow-field plate constructed from polymethylmethacrylate (PMMA) is developed herein to reduce the weight of the PEMFC system. Computer-aided engineering (CAE) mold flow analysis is then used to simulate the experimental design based on the finished products. Experimental analysis is also performed on the adhesion results of the plates. The results indicate that the establishment of the injection mold using CAE simulation improves mold development and reduces cost. Mechanical coarsening on the surface of the PMMA results in improved adhesion (> 50 N) at temperatures higher than 80 °C. Thus, mechanical coarsening is suitable for the PEMFC system. The problem of conventional weight is solved by reducing the weight by 70%.

A series of six-membered sulfonated poly(imide-siloxane)s (SPIs) was synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), aminopropyl-terminated polydimethylsiloxane (PDMS) 2,2-benzidinedisulfonic acid (BDSA), as the sulfonation target diamine groups, and various nonsulfonated diamine monomers behaving as bridging groups. The structure-property relationship of SPI-SXx membranes is discussed in detail according to the chemical structure of the various nonsulfonated diamines of the SPI-SXx membranes from the viewpoints of proton conductivity, ion exchange capacity (IEC), and membrane properties (water uptake and membrane swelling) at equal PDMS content SPI-SXx. The PDMS was introduced to enhance the proton conductivity and water uptake attributed from the high flexibility of the siloxane segments. The conductivity and water uptake of angled SPI-SXm and oxydianiline-based SPI-SX membranes (SPI-SXO) are greater than those prepared from diaminodiphenylmethane-based SPI-SX membranes (SPI-SXD) at a given IEC. These differences resulted from the increased number of entanglements of the SPI-SXx membrane. The SPI-SXD showed almost isotropically dimensional changes with the increase in water uptake, and the volume were slightly smaller than those estimated from the additivity rule. Free volume in the SPI-SXx increased with the increase in bulky irregular packing in nonsulfonated segments, which augmented the water uptake and, in turn, the conductivity of the polymer. With the increase in temperature, conductivity increased more rapidly in SPI-SXx than in Nafion 117. Microscopic analyses revealed that these smaller (<10 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. The new sulfonated poly(imide-siloxane)s have proved to be a possible candidate as the polymer electrolyte membrane for polymer electrolyte fuel cells (PEFCs) and direct methanol fuel cells (DMFCs).