A polymer bearing five-membered cyclic carbonate in the side chain, prepared by radical polymerization of 4-methacryloxymethyl-1, 3-dioxoran-2-one, was crosslinked with L-lysine. In spite of the twitter ionic character of L-lysine, the crosslinking proceeded efficiently in a dimethylsulfoxide solution using excess amounts of L-lysine over the carbonate group. In the crosslinking reaction in aqueous media, there took place the hydrolysis of the cyclic carbonate group concomitantly. The elucidation of the water absorbency revealed that the resulting crosslinked polymer contained carboxylate group that is in the neutralized state in a basic aqueous solution.

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The reaction behavior of polyalkenamers with 5-memberd cyclic carbonate 3 was examined. In the case of polymer 3 on cationic ring-opening with higher molecular weight (Mw) than ca. 5500, the cationic ring-opening reaction proceeded to give the corresponding DMSO-insoluble networked polymer. In addition, the degree of the volume change on the crosslinking was suggested to be controllable by the Mw and structure of polymer.

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Nowadays, gold is very often used in electric circuits. Most of the resins can, however, hardly adhere to gold. This is a serious problem for applying the resins to electric circuits. The fact is well known that sulfur can bond to gold easily. Then it is considered that the adhesion of a resin to gold may be improved if sulfur is introduced to the resin to form the bond between sulfur and gold. We synthesized certain phenol derivatives containing thiol or disulfide groups, and added them to an epoxy resin which was used in most of the electric circuits. As a result of measuring their effect on the adhesion property, the adhesion strength was decreased when the phenol derivatives contained thiol groups. The reason was considered to be as follows : the thiol groups had reacted with epoxy groups for partially hindering the polymerization of the epoxy resin, thus resulting in decreasing the strength of the resin itself. Also we got the results by quantum chemistry calculation that the S-S bond of the disulfide group was dissociated and the Au-S bond was formed when the dissociated sulfur came near to gold. In conclusion the adhesion property was measured on the epoxy resin, to which a synthesized phenol derivative containing disulfide was added by 2wt%. The result showed that the adhesion strength and energy were increased by 12%, and 24%, respectively.

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The activity of various carboxylates with alkaline metals as an anionic catalyst for epoxides was evaluated by following chain propagation in the catalyzed polymerization of monoepoxides. In addition, T_g-disappearing phenomenon in dynamic viscoelastic behavior of cured resins was investigated when the carboxylates were used as a curing catalyst for bisphenol A type epoxy resins. It was revealed that the carboxylates with alkaline metals could make epoxides polymerized into higher polymers in a far shorter time than conventional anionic catalysts such as imidazoles could. More significantly, T_g-disappearing phenomenon was observed on using anionic catalysts with higher activity for curing. Based on these results, the mechanism of T_g-disappearing phenomenon was suggested.

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Synthesis of anisole novolacs from methoxybenzyl alcohols is described. Sulfuric acid-catalyzed self-condensation of 2- or 4-methoxybenzyl alcohol (hydroxymethylanisole) in acetic acid afforded the corresponding anisole novolacs in good yields. The resulting novolacs were well-soluble in common organic solvents such as chloroform, tetrahydrofuran, and acetone but insoluble in methanol. The structures of the polymers were determined by ¹H & ¹³C NMR and IR analyses. From the ¹³C NMR analysis, these novolacs were clarified to have a linear structure. From the GPC analysis (by the polystyrene standard), the number average molecular weight was found to be about 2000. Under these polymerization conditions, only were obtained oligomers having such the molecuar weigt. This formaldehyde-free synthetic method is expecyed to give novolacs with controlled structures.

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Present electrical devices have large calorific power, and improvement of heat dissipation has been a very important subject. In this paper, we developed the novel epoxy resins with increased thermal conductivity, the insufficiency of which has been a barrier to heat dissipation. The medium of thermal conduction for insulating resins is phonons. Phonon conduction depends on the crystallinity, since it is caused by a lattice vibration. The scattering of phonons happens on the interface of an amorphous structure. If there is a macroscopic amorphous structure so long as crystal structures exist on the microscopic level, we expected that high thermal conduction can be attained by reduced scattering of phonons through controlling the nano scale structure. Using an epoxy resin which has the mesogen structure would solve this problem because of easily carrying out an orientation with this structure. As a result, we confirm that thermal conductivities become higher with increasing amounts of mesogens. The epoxy resin (A) contains biphenyl mesogen, and the epoxy resin (B) contains even bigger mesogenic units. The thermal couductivity of the epoxy resin (A) was about two times higher than that of a conventional epoxy resin, and a much high value of five times was able to be attained in the case of the epoxy resin (B).

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This is the 3rd report entitled “Plastic Lining-Today's Trends, ” which describes mainly “Epoxy Resins, ” following the previous reports of “Unsaturated Polyester Resins” and “Vinylester Resins.” In the former part of this report, epoxy resin coatings for steel structures are described. Indeed, strictly speaking, coating and lining should be distinguished although coating with epoxy resins are so much applied worldwide for the fields of author's intention to describe. The latter part of this report describes plastic lining with epoxy resins after defining “LINING” and “COATING.” The applications of such lining are not only to steel structures but also to concrete substrates in water and waste water works. Among many kinds of network polymers, “epoxy resin” may have the most potential for further research and development. As one of derivatives from it, there are vinylester resins. Their precise synthetic and molding technologies will open the door for tomorrow.

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