SynopsisIn this study, we carried out successive cleavage of the ether linkages of lignin through the reverse pathway of lignin biosynthetic mechanism. The first step is cleavage of benzyl aryl ether through the phase-separation system. The second step is cleavage of C-beta aryl ether linkages of lignophenol by the mild alkaline condition. The third step is demethylation of the aromatic methoxyl groups leading to monophenols by Lewis acid treatment. Through these cleavage of ether linkages of lignin, we achieved activation and depolymerization of lignin for chemical feedstock.

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SynopsisIn this study, biocomposites of an oil-based network polymer and cellulose have been developed. Powdery cellulose was treated in water by a wet disk milling method to produce the dispersion of the cellulose ultrafine fibers, which was subsequently subjected to the direct lyophilization or the lyophilization after the solvent displacement of water with t-butanol. These cellulose fibers were used as a filler for the preparation of the composites by the acid-catalyzed curing of epoxidized soybean oil. The significant reinforcement effects were observed by the incorporation of the cellulose fibers. The composite having relatively high transparency was formed by using the cellulose fiber obtained by the lyophilization with t-butanol

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SynopsisThe glass transition temperatures(T_gs) and tensile properties of the alcohol-liquefied wood-based epoxy resins were studied in relation to the biomass content in the resins. Firstly, the planet-type ball-mill crushing was conducted to the wood powder as a pretreatment of the wood liquefaction. The pretreatment was effective to break the crystalline structure of the cellulose in the wood. As the results, the biomass content in the alcohol-liquefied wood was increased to 63wt%. After that, wood-based epoxy resins were synthesized from the alcohol-liquefied wood with various biomass contents. The T_gs, the tensile strengths and the tensile moduli of the cured wood-based epoxy resins increased with increasing the biomass content in the resins. The rigid chemical structure of the wood-derived molecules would result in the high T_gs and the high mechanical properties of the wood-based epoxy resins.(Received January 5, 2011 ; Accepted February 10, 2011)

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SynopsisCarbon-neutral materials, which do not affect the density of CO₂ in the atmosphere even if they burn, have attracted much attention from the viewpoint of environmental friendliness. In this study, waste medium for cultivation of plant (natural lignocellulose) was decomposed stepwise and converted into the useful materials for epoxy/hardener system which were not derived from petroleum. In the first decomposition, the natural lignocellulose was treated with high-pressure hot water.The epoxy resin containing the hydrothermally treated lignocellulose (HLC) fillers had the higher fracture toughness than that of the base epoxy resin (without fillers). Therefore, the HLC works an organic filler. In the next decomposition, the HLC was treated with acidic H₂O/C₂H₅OH solution under high temperature and pressure. The prepared acidolysis lignin(ALG), which had lower molecular weight than that of the HLC, was utilized as a hardener for epoxy resin. Moreover, the epoxidized ALG (ep-ALG) was prepared by epoxidation of the phenolic group of the ALG. The measurements of cross-link density and glass transition temperature of the epoxy/hardedner/ep-ALG system demonstrated that the ep-ALG with high cross-link activity improved heat-resistance of conventional epoxy/hardener system.

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SynopsisWith the objective of high durability and heat-resistance biomass resin development, new eco-friendly phenolic resin was synthesized starting from starch. Newly developed PHENOLIC BIOMASS RESIN, which was cured by epoxyresin, provided comparable performances to those of conventional phenolic resin for high heat resistance and mechanical properties. And also, it showed its excellent water resistant property. As further development, EPOXIDIZED BIOMASS RESIN was synthesized. EPOXIDIZED BIOMASS RESIN which was cured by PHENOLIC BIOMASS RESIN showed excellent mechanical properties.

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SynopsisRecently, highly efficient reactions of CO₂ and their exploitation in designing new materials have attracted considerable attention. So far, we have focused on the reactivity of CO₂ as one of heterocumulenes, and have succeeded in the highly efficient synthesis of 5-membered cyclic carbonate by the reaction of epoxide and CO₂ under atmospheric pressure. This review article describes 1) the efficient utilization of CO₂ as a C1 chemical that involves its reaction with epoxide under mild conditions without any external supply of energy, 2) the characteristic reactivity of 5-membered cyclic carbonate, i.e., the highly chemoselective reaction with amine, 3) polymer synthesis based on this characteristic and advantageous reaction, and 4) the current status and the future prospect of synthesis of functional networked polymers based on the synthesis and reaction of 5-membered cyclic carbonate.

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[in Japanese]

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