Selective anionic ring-opening of carbonate monomer (65CC) containing five- and six-membered cyclic carbonate moieties was carried out to obtain a polycarbonate carrying five-membered carbonate structure in the side chain (poly65CC). The reaction of the obtained polymer with monoamines was examined to give predominantly polycarbonate bearing hydroxyurethane moiety in the side chain through the addition of five-membered carbonate with amines. Based on these model reactions, selective reaction of five-membered carbonate in the side chain of poly65CC and hexamethylenediamine was carried out to form a network polymer through hydroxyurethane linkages. In the presence of 1,8-diazabicyclo[5.4.0]-7- undecene (DBU), under a dilute condition, depolymerization of the main chain of the networked polycarbonate proceeded to regenerate the original monomer 65CC with five- and six-membered carbonate structures.

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Polymerization behavior of epoxides initiated with benzoyl group containing sulfonium salts with PF₆^- anion was evaluated. Polymerization rate was related to molecular orbital calculations (MOPAC program with AM1 parameter) and Hammett constant. Polymerization activity of the sulfonium salts having substituents at the p-position of benzoyl group was as follows ; NO₂ (4-NBPBS・PF6) > H (4-HBPBS・PF6) > CH₃O (4-MOBPBS・PF6) ≈CH₃ (4-MBPBS・PF6). In the crosslinking with 4-NBPBS・PF6, yellowish networked polymer was obtained. Based on these results, 4-HBPBS・PF6 is expected to be the most promising salt as a novel thermally latent polymerization initiator for electronic materials.

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This paper presents the synthesis of polyspiroketal bearing reactive pendants and its crosslinking reaction based on radical thiol-ene reaction. For synthesizing the polyspiroketal, a tetraol bearing two allyl ether moieties was prepared from myo-inositol, a naturally occurring cyclic hexaol, and was condensed with 1,4-cyclohexanedione with the aid of azeotropic removal of the formed water. The resulting polyspiroketal was endowed with allyl pendants, which was readily functionalized by thiol-ene reaction using monothiols. The high efficiency of the functionalization allowed successful crosslinking reaction of the polyspiroketal using dithiols to yield the corresponding networked polymers.

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We have reported that multifunctional hyperbranched polymers are synthesized by radical homopolymerization of ethylene glycol dimethacrylate in the presence of methyl (2-bromomethyl)acrylate as an addition-fragmentation chain transfer agent. The hyperbranched polymers contain the pendant vinyl groups and the ω-end vinyl groups, and exhibit thermosetting properties in the absence of any catalyst. In this study, the initiation mechanisms for the thermal curing of the hyperbranched polymer were investigated by radical trapping using a nitroxide free radical. The hyperbranched polymer reacted with 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxy benzoate by heating at 150 °C showing that the curing proceeded by radical mechanism. The ¹H NMR analysis of the product revealed that the cleavage of Br－CH₂ bond and C －C bond adjacent to a vinyl group having relatively low bond dissociation energies has minor contribution to the radical formation and thermal curing proceeds by spontaneous polymerization of vinyl groups.

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Alkylborane is a kind of the living radical polymerization initiators. Through oxidation of alkylborane in the air, it forms the dormant species at the end-group of polymer chains. We therefore investigated a restoration of fractured thermosetting polymer by alkylborane-dormant which had a re-polymerization function with monomer. When we spread the monomer on the fracture surfaces of the thermosetting polymer and put the pieces together with heating, the fractured parts were perfectly bonded each other recovering the original strength and thermostability. We estimated that the alkylborane in the fracture surfaces was oxidized through exposure to air to initiate polymerization of the monomer. Meanwhile, we applied the restoration process for thermosetting polymer with peroxide, but it didn’t show any adhesion to each other.

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The mesogenic epoxy resins, which mesogenic groups as a rigid structure in their backbone were introduced, show the high performance and high functional properties, comparing conventional epoxy resins. The relationship between the ordered epoxy network structure formed by self-organization of mesogenic groups and their physical properties (Fracture toughness, thermal property and thermal conductivity) was discussed.

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