In recent years, with downsizing of electronic information terminal devices and high-speed transmissions and processing of large capacity information, lower dielectric constant has been required for the circuit boards which are usually made of epoxy resins. Currently, active ester resins have been attracted much attention as epoxy hardeners which can afford low dielectric materials. The active esters give the cured epoxy resins low dielectric constants and high water resistance, because no hydroxyl groups derived from the epoxy resins are generated. In this study, we applied the concept of active ester resins, and aimed to create a new active phosphate ester curing agent of epoxy resins. We synthesized various phosphate esters and investigated their reactions with mono-functional epoxy resins. As a result, we found that dimethylphosphinate or N,N’-dimethylamidophosphate can react with mono-functional epoxy resin. Furthermore, we synthesized an multifunctional active phosphate hardener based on N,N’-dimethylamidophosphate, and prepared a cured epoxy resin. Contrary to expectation, the cured epoxy resin was high water absorption. However, T_g of the cured epoxy resin and char yield after thermal decomposition were high value. These data suggested that the phosphate hardener can give the high thermal resistance and flam retardancy.

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Radical copolymerization of 5-(methacryloyloxy)methyl-1,3-oxathiolane-2-thione (DTC) and styrene derivatives such as 4-(t-butoxy)styrene, 4-(t-butyldimethylsiloxy)styrene, and 4-trimethylsiloxystyrene were carried out in tetrahydrofuran using 2,2’-Azobis(isobutyronitrile) (AIBN) as a radical initiator. The copolymerization proceeded smoothly to give the corresponding polymers in high yield. The copolymer composed of DTC and 4-trimethylsiloxystyrene was deprotected by addition of 1M HCl aq. in ethyl acetate to give the corresponding copolymer having DTC and phenol structures. Thermal properties of the obtained polymers were evaluated by thermal gravimetric analysis (TGA) and differential scanning calorimetry Synopsis (DSC). These polymers showed 10 wt % loss temperatures (T_d10) in the range from 191 to 234 ℃. The polymers obtained here exhibited glass transition temperature (T_g) in the range from 105 to 139 ℃. Furthermore, cyclic dithiocarbonate moieties in the copolymers underwent a ring-opening polymerization by heating in the presence of 4-hydroxyphenylbenzylmethylhexafluorophosphate as a thermally latent cationic initiator to give the corresponding ross-linking polymer.

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In order to form robust hydrogels based on a combination of ionic and hydrophobic interactions, we designed diblock polymers with sodium sulfonate units based on thiol-ene addition to poly(styrene-b-allylglycidylether) and triblock polymers with guanidinium hydrocholoride units based on thiol-ene addition to poly(allylglycidyl ether-b-ethylene oxide-ballylglycidylether). Significantly, combination of these two polymers successfully afforded robust hydrogels at 80 wt% water content retaining its shape even when the mole fraction of ionic charge was varied.

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The mechanism for a polymerization under UV light exposure without using initiators in liquid crystals was investigated in this study. Experimental results of IR spectroscopy, HPLC, SEM and TEM revealed that the polymerization of the monomer 2,6-dimethacryloyl-oxy-naphthalene (2,6-DMANaph) was presumed to be initiated with radicals derived from the monomer as reactive intermediates of photo-Fries rearrangement. As the initiators are not needed when polymer layers are formed in liquid crystal cells with the monomer 2,6-DMANaph, voltage holding ratio of the liquid crystal cells is kept high, indicating that the applications toward liquid crystal devices are possible.

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Carbon fiber reinforced plastics (CFRP) attracts attention with increasing the requirement to reduce the weight of automobiles. The important issue for applying CFRP widely to mass-produced cars is to realize the high productivity equal to the conventional steel material. We focused to resin transfer molding (RTM) process, and aimed to reduce the molding cycle time of RTM within 10 min. At the mold temperature, the resin should not react for a while and maintain the fluidity at the injection process, and then stiffen immediately to the glass state to demold without deformation. In this paper, we investigated to design the epoxy resin system which could balance the long flow time and the short cure time by using the dielectric analysis. On the basis of reaction kinetics, we confirmed the advantage of an anionic polymerization system to balance them compared with the conventional amine curing system. And we achieved the target by applying an alcohol for chain transfer reaction and an acid anhydride for alternating copolymerization respectively. In addition, we succeeded in molding the large-scale CFRP of the anionic polymerization resin system by RTM in 10 minutes.

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Requirements of safety and reliability in batteries, power devices, and sensors have been increasing more and more in recent years, and one considers that safer and higher performance novel electrolyte materials should be developed in various fields. Liquid electrolytes have been widely used as ion-conducing electrolyte materials, but now gel electrolytes and solid polymer electrolytes have been currently developed to solve safety problems such as liquid leakage, evaporation of solvents, combustion, and so on. In this review article, we describe about (i) development of networked polymer solid electrolytes, (ii)development of ionic liquid gel electrolytes based on networked polymers with ionic liquids, and (iii) development of gel electrolytes for lithium-ion batteries by using networked polymers with carbonate-based liquid electrolytes, which we have recently developed.

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