In this study, we report novel polymer alloy which has high heat resistant and low CTE. In our previous study, 4,4’-bismaleimide diphenyl methane (BMI) and P-d-type benzoxazine (P-d) were allowed to react in order to obtain a high heat resistance resin. However, the disadvantages in this case were the high processing temperature (>160℃) and the narrow process window (the narrow temperature range available for processing). Thus in this research, we addressed these problems by copolymerizing bisphenol A dicyanate ester, which has a low melting point and high heat resistance, with BMI and P-d. The optimum equivalent ratio and curing conditions were determined from the processability and thermal properties of the resins. As a result, this ternary alloy resin realized low processing temperature at 120°C and viscosity of 23 mPa・s, while those of our previous system (BMI+P-d) were 160°C and 36,000 mPa・s, respectively. The cured resin has a T_g of more than 250℃, a CTE of less than 50 ppm/K, and higher flexural strength than that of conventional epoxy resins, thus satisfying the requirements for an encapsulation material to be used in SiC semiconductors.

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Cross-linkings of methacrylate copolymers obtained by radical copolymerization of 2-isothiocyanatoethyl methacrylate (ITEMA) and 2-hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA) were examined.Poly(ITEMA-co-HEMA) was cross-linked at room temperature in tetrahydrofuran (THF) by adding 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) as a catalyst, to provide the corresponding networked copolymer. Further, poly(ITEMA-co-HEMA) and poly(ITEMA-co-MAA) were cross-linked by heating without any catalysts to give the corresponding networked copolymers, respectively. By IR spectroscopy, it was confirmed that the isothiocyanato group reacted with the hydroxyl group or the carboxyl group in the side chain of the copolymers to afford the networked copolymers. Based on these results, it was concluded that poly(ITEMA-co-HEMA) and poly(ITEMA-co-MAA) have latent ability of cross-linking and that they are useful as key materials for networked copolymer formation.

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We report synthesis and utilization of epoxy resin derived from lignin (L), which is classified as a plant biomass with a polyphenol structure. L is considered to be a suitable alternative to petroleum-derived phenolic resins used for preparation of epoxy resins. Thus, we synthesized epoxidized lignin (EL) by the reaction of L with epichlorohydrin and cured the resulting EL by using phenol novolac (PN) as a curing agent. At first, the effect of phase-transfer catalysts on epoxidization was examined by model reaction using coniferyl alcohol (CA). CA was allowed to react with epichlorohydrin by a two-step process in the presence of the catalysts, and it was found that the catalysts composed of ammonium cations with alkyl chains longer than ethyl group were suitable for epoxidization. Then, L was epoxidized by using tetraethylammonium chloride as a phase-transfer catalyst. As a result of optimization of synthetic conditions, EL with low epoxy equivalent weight and with softening point was obtained in good yield. The resulting EL was cured with PN to give a cured resin containing about 75wt% of biomass-derived component.

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Mechanical and thermal properties of composite materials containing steam-exploded lignin (hereinafter called “lignin”) were investigated. Thermal resistance and mechanical properties of lignin-epoxy resin and lignin-containing phenolic resin were excellent compared with those of using fossil-derived phenolic resin. The resin flow was controlled by optimizing additive amount of resin and filler. The complex shaped molding articles were obtained by compression, transfer and injection molding. Peel strengths of lignin-containing phenolic resin composite materials with aluminum and copper foils were higher than those of composite materials using fossil-derived phenolic resin.

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The organic－inorganic hybrids are functional materials that organic and inorganic components are dispersed in a nanometer order. The optical use of these materials is expected, because highly transparency. In order to prepare these organic－inorganic hybrids, the formation of crosslinking is essential, and the photo-crosslinking is one of most candidates for the quickly accomplishment of organic－inorganic hybrids. Since the inorganic components are often synthesized by the sol－gel method, the simultaneous photo-crosslinking with organic components in the sol－gel reaction is the important procedure for the preparation of organic－inorganic hybrids. For example, the photo-assisted thiol-ene reaction, which was proceeded with vinyl silane coupling agent and multifunctional thiol, and the sol－gel reaction of silane coupling agent generated the organic－inorganic hybrid. Furthermore, the surface modified metal oxide nanoparticles are used as the inorganic components for the organic－inorganic hybrids. In this point of view, a high refractive index hydrid can be readily produced by photo-radical crosslinking of multifunctional acrylates and zirconia hanoparticles with methacrylic groups. It is possible to control the refractive index by the content of the zirconia nanoparticles in the hybrid thin film. In this paper, we will describe about the recent development of organic－inorganic hybrid using the photo crosslinking polymers.

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