Epoxy resin is widely used in various industries due to its superior properties. Advancement of all the properties of epoxy resin is required by recent technology development, especially the poor toughness and heat resistance. Moreover, excellent adhesive properties for metals (e.g.; copper, gold, aluminum, silver etc.) to which it is hard to adhere, have also been desired for epoxy resin in the electric and electronics industrial fields in recent years. In order to achieve both an increase in the adhesive strength to metal and an improvement in the toughness of cured epoxy resin, the introduction of polymers containing sulfur, which has strong interaction with metals, was investigated. A polyester and polythioesters containing sulfur were employed as modifiers for epoxy resin. The effect of the added modifiers was evaluated by single-lap shear, Charpy impact and fracture toughness testing. The sulfur-containing polymers have a beneficial effect on the enhancement of the epoxy resin/metal junction. The most effective example was the addition of 20 phr of the MPS_7 polythioester to epoxy resin increased its adhesive strength to copper from 5.7 to 17 MPa. The addition of these modifiers was also effective in improving the impact strength of epoxy resin.

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The catalytic activity of H2PtC16 in the hydrosilylation was evaluated in the presence of sulfide derivatives to clarify the relationship between the sulfide structures and their controllability of the hydrosilylation process. From the study on the hydrosilylation reaction of trimethylvinylsilane with triethylsilane at various temperatures, it was found that the catalytic activity depended upon the substituents on the added sulfide derivatives. In case of disulfide derivatives, the catalytic activity was remarkably suppressed compared with the case of mono sulfide derivatives in observing the same tendency to the model reaction. Effective control of the catalytic activity was shown applicable to the crosslinking reaction of silicone resin.

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The topography of silane layers deposited on an inorganic surface was observed using atomic force microscopy. For this purpose, cleaved mica plates were treated with certain silane coupling agents at various conditions. There were used silanes having various organic functional groups such as vinyl-, amino-, etc. with di- and trialkoxy structures. Four different solvents, i.e. 2-propanol, 2-propanol/water mixture, water, and toluene, were used for silane solutions. The pH of each aqueous solution was controlled. As a result, the need of a suitable solvent and pH was clarified in order to obtain a smooth silane layer. The following three factors were found to be important parameters for this purpose : the solubility of silane in the solution; the wettability of silane onto the inorganic surface; and the restraint of the self-condensation of silane molecules in the solution

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The determination of the branch density was performed using ¹³C-NMR spectroscopy for high-ortho and random novolacs prepared by the conventional zinc acetate-catalyzed and oxalic acid-catalyzed polycondensation, respectively. The phenoxy carbon chemical shifts were assigned using several kinds of novolacs having different molecular weights and ortho ratios of methylene linkage. In dioxane, the phenoxy carbon chemical shifts of the branched, linear, and terminal phenolic units were 149.2-151.4 ppm, 151.4-153.8 ppm, and 153.8-156.7 ppm, respectively. The molar percentages of the branched, linear, and terminal phenolic units in novolacs were dependent on the molecular weights of the novolacs. However, there was no difference in the branch density between high-ortho and random novolacs.

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The preparation of new novolacs from natural phenolic compounds such as vinillyl alcohol (2), o-vanillin (4), eugenol (6), and 2-allyl phenol (8) using the acid-catalyzed phenol-formaldehyde condensation or self-condensation is described. The eugenol novolac (7) was prepared by the hydrochloric acid-catalyzed polymerization of eugenol (6) with formaldehyde in good yield. The structure of 7 was supported by its ¹H NMR and FT-IR spectra. Compound 7, which has a well-defined structure was soluble in THF, DMF, and acetone. The preparation of poly (vanillin) (3) by the acid-catalyzed self-condensation of vanillyl alcohol (2) is also discussed. These polymers are new artificial polyphenols and expected to be used as a medicine, antioxidant, etc. The functional novolacs having the allyl group (7, 9) have considerable material potential as a reactive polymer and an adhesive.

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An overview of the development of asymmetric aromatic polyimide thermosetting resins and their composites is presented. Aromatic polyimide has been intensively investigated for applications in wide industry in addition to a fundamental aspect. However, the development of thermosetting polyimides for heat resistant molding compounds and the composites has been suffered because of difficulty with processing due to the rigid and planar symmetric structures. Based on a recent research of asymmetric aromatic structures, those polyimide oligomers with reactive phenylethynyl end caps have been developed. The highly bend and asymmetric aromatic structures are expected as the key materials in obtaining high performance and heat resistant polyimide resins as well as the composites with high fracture toughness and good processability.

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Polybenzoxazine is a novel type of phenolic resin that is prepared by the ring-opening polymerization of a cyclic monomer. Cyclic monomers are easily prepared in high yields from amines, phenols, and formaldehyde. Polybenzoxazines, like typical phenolic resin, have advantageous properties such as excellent thermal properties, inflammability, electrical properties, and so on. They also possess various characteristics, that are not found in the typical phenolic resin, like molecular design flexibility, no evolution of volatiles during the cure process, and excellent dimensional stability. The problems that have to be solved are relatively high curing temperature and the brittleness of the cured materials. Further improvement of thermal properties is also expected. As the method for high performance polybenzoxazines, designing of cyclic monomers, preparation of high molecular weight and soluble precursors, polymer alloys, and organic-inorganic hybrids have been examined, and were found to be effective for the improvement of thermal and mechanical properties and lowering the cure temperatures.

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