In this study, network polymers from epoxidized plant oil with bio-based phenolic polymers, terpene-modified phenolic resin or lignophenol, have been developed. The glossy network polymers were prepared by an acid-catalyzed curing of epoxidized soybean oil with these bio-based phenolic polymers. The product polymer with terpene-modified phenolic resin showed higher mechanical properties than the ESO polymer. The flexibility was much improved by the addition of terpenemodified phenolic resin. The micro phase-separation was observed in the network polymer with lignophenol.

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Epoxy/titania hybrid materials with a high refractive index were prepared with diglycidyl ether of bisphenol-A, 3-mercaptopropyl-trimethoxysilane, and titanium-tetra-isopropoxide via a sol-gel process by using a multistep curing. The bond formation between organic and inorganic phases was performed using 3-mercaptopropyl- trimethoxysilane as a coupling agent. The hybrid materials were characterized by FT-IR, 1H-NMR, TGA, CP-MAS²⁹Si-NMR, TEM, UV-vis methods. The experimental results showed that the titania network was homogeneously dispersed in epoxy matrix. The refractive indices of the prepared hybrid materials were increased from 1.587 to 1.645 with an increase in the titania content. Excellent optical transparency for visible right was attained for the prepared hybrid materials.

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We succeeded in the development of a novel liquid epoxy resin providing both of excellent flexibility and outstanding toughness to its cured resins. The main drawback of epoxy resins “Stiff but Brittle” was largely improved by an epoxy resin based on bisphenol A and modified with a high concentration of a flexible skeleton.
We were able to synthesize the new type of epoxy resin by reaction of bisphenols with vinyl ethers, leading to phenolic intermediate having a special acetal structure. This phenolic intermediate was epoxidized by epichlorohydrin. The resulting epoxy resin exhibit both high flexibility and excellent toughness after curing. In view of this, it was expected that such epoxy resins are able to solve the problems and future demands in difficult high-tech applications, such as printed circuit board and the like.
The excellent performance is considered to be based on the synergy effect of the hard-segment (with the molecular mobility reduced by cross-linking points located closely to that hard segment) providing much larger strength and the soft-segment (mobility of which was larger because of the position far from cross-linking points) performing excellent flexibility.

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Epoxy resins with controlled high-order structures show higher thermal conductivity than conventional ones, because the crystal-like domains consisting of self-arranged 'mesogen' groups of epoxy monomers promote smooth phonon transportation. Thermal conductivity of these epoxy resins is 1.0 W/mK at most, and this value is not enough to apply these neat resins to electric devices which require high radiation efficiency. In this paper, we investigated the composites consisting of these resins and ceramic fillers, in order to obtain the epoxy resin composites which have both isotropic high thermal conductivities and electrical insulation. Though these epoxy monomers are difficult to handle because of their crystallinity and poor solubility in solvents, we confirmed that the conventional processes for thermosetting resin forming, such as “varnish coating” and “transfer molding”, are applicable to these composites by optimizing the molecular architectures of hardeners, the composition of solvents, etc. As a result, excellent thermal conductivity as high as 10 W/mK was attained for the composites using the polycyclic mesogen type epoxy monomers.

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A new epoxy resin containing trisbenzyl isocyanurate moiety (TGBIC) was synthesized by the reaction of epichlorohydrin and a phenolic compound which obtained from cyanuric acid, 2, 6-dimethylphenol, and paraformaldehyde. In order to evaluate the effect of trisbenzyl isocyanurate moiety on the thermal properties, triglycidyl isocyanurate (TGIC) and diglycidyl ether of 3, 3', 5, 5'-tetramethylbisphenol-F (DGTBF) were used as references. The cured polymer of TGBIC with phenol novolac showed glass transition temperature of 189.2 °C in DMA measurement which was 47.6 °C higher than that of the DGTBF polymer, and gave initial thermal decomposition temperature of 332.1 °C which was 71.9 °C higher than that of the TGIC polymer. These results might be attributed to the aromatic structure and the rigid isocyanurate moiety in TGBIC.

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Free-radical crosslinking polymerization behavior of triallyl isocyanurate (TAIC) was specific as compared with those of common multiallyl monomers. This is due to the steric effect on the transition state formation in the reaction at the sterically crowded, terminal reaction site of growing polymer radical caused by the sequential, bulky TAIC units, i.e., the reduced monomer chain transfer, the non-terminal units effect on the cyclopolymerization of TAIC, and the sequence length dependence of steric effect on the reactivity of growing polymer radical. Non-filled TAIC cured resin was too brittle for practical use. The brittleness of crosslinked resins has been conceived to be due to the inhomogeneity of their network structures consisting of colloidal particles; however, the complete loss of flexibility of poly (TAIC) chain does not satisfy the prerequisite of the locally-enhanced occurrence of intramolecular crosslinking reaction inducing microgelation to form a colloidal particle. Therefore, the correlation between brittleness and network structure of TAIC resins was further discussed, especially focusing on the characterization of resulting TAIC network polymer precursors (NPPs). Thus, an alternative explanation for the brittleness of TAIC resins is provided : the insufficient growth of the network structure of TAIC resin because of steric hindrance on the crosslinking reaction between sterically crowded growing polymer radical and pendant allyl groups belonging to the rigid primary polymer chains at the surface of coreshell type dendritic NPP. This was extended to the mechanical formation of finely divided particles originated in an extreme brittleness of TAIC resin, and, furthermore, we proposed that a network polymer should be considered as “a crosslinked system material” consisting of NPP modules as metastable intermediates of crosslinked polymers in place of “an indefinitely large sized, giant molecule”.

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This paper reviews recent studies on cage type silsesquioxane (SSQ) /epoxy resin nano-composites. Many kinds of cage type SSQs, which have various organic substitutional groups including epoxy ones, are used for these nanocomposites studies. Major factors governing nano-composites properties lie not only in the type of SSQ but also in the network forming process and the resulting morphology of the SSQ/ epoxy resin network. Studies on network forming behavior and cross-linked network structure model are summarized in Tables by type of epoxy-functional SSQ. Other studies on nano-composites properties are also classified by type of SSQ used and listed in Tables as well as epoxy resin formulations and other conditions for overall understanding of the trend in the cage type SSQ/epoxy resin nanocomposites study.

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