Radical copolymerization of 5-(methacryloyloxy)methyl-1,3-oxathiolane-2-thione (DTC) [1] and 2-hydroxyethyl methacrylate (HEMA) [2] were carried out in dimethyl sulfoxide (DMSO) using 2,2’-azobis(isobutyronitrile) (AIBN) as a radical initiator. The copolymerizations proceeded smoothly to give poly(DTC-co-HEMA)s with various compositions in almost quantitatively. Thermal properties of the obtained polymers were evaluated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The obtained polymers showed 5 wt% loss temperature (T_d5) in the range from 163 to 204℃. The polymers obtained here exhibited glass transition temperature (T_g) in the range from 63 to 93℃. The copolymer with 4 mol % DTC content could be cross-linked by using 4,7,10-trioxa-1,13-tridecanediamine or poly(ethylene glycol) bis(3-aminopropyl) terminated (M_n = 1500) as a cross-linker. The obtained networked polymers were swollen in water exhibiting 165 and 242% swelling ratio, respectively. It was also found that lysine ammonium salt could be used as a crosslinker of the poly(DTC-co-HEMA).

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A series of N-(pyridyl)benzamides were synthesized from 4-aminopyridine (4AP) by acylation of its amino group with p-substituted benzoyl chlorides and used as novel initiators for polymerization of diglycidyl ether of bisphenol A (DGEBA). Heat evolution by the polymerization was evaluated by differential scanning calorimetry (DSC). The resulting DSC profiles indicated exothermic peaks, of which peak top temperatures were 143－154℃, which was 20℃ higher than that observed for the polymerization using pristine 4AP as an initiator. The initiation activities of these benzamides were controlled by the character of substituent on the benzene ring. It is supposed that the electron density on the nitrogen atom of amide bond affected the reaction temperature. A good correlation was obtained between the DSC peak top temperatures and Hammett constants of the substituents on the benzene ring. The DSC peak top temperature became higher as the substituent group became electron-withdrawing. The initiating mechanism would involve nucleophilic attack of the nitrogen atom in the pyridyl group in the benzamides to epoxide.

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Network formation of poly(γ-glutamic acid) (γPGA) having catechol structure at room temperature in aqueous media was examined, and its application to biocompatible adhesives was investigated. Carboxyl groups of γPGA was partially transformed to an activated succinmide ester form, SI-γPGA, by treatment with hydroxysuccinimide and watersoluble carbodiimide. Addition of 3-hydroxytyramine (DOPA) hydrochloride in γPGA in NaHCO₃ solution gave DOPAmodified γPGA. On the other hand, immediate gelation was observed by addition of 4,7,10-trioxa-1,13-tridecanediamine (TODA) in a polymer aqueous NaHCO₃ solution, which indicated formation of networked polymer by diamine crosslinking. Simultaneous addition of DOPA hydrochloride and TODA to the SI-γPGA solution caused rapid gelation of the polymer solution, which indicated the formation of networked γPGA partially modified with DOPA. Solutions of SI-γPGA/TODA/DOPA mixture and SI-γPGA/TODA mixture were put on the surface of a pig skin and covered with another pig skin and pressed for 24 h, respectively. The adhesion property was evaluated by mechanical tensile measurements. As a result, detaching force of SI-γPGA/TODA/DOPA sample was more than three times higher than that of SI-γPGA/TODA, indicating the high adhesion property of DOPA-modified γPGA.

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The episulfide resins with fluorene backbone moiety were synthesized by replacing the oxygen atoms on the oxirane ring of bisphenoxy ethanol fluorene epoxy resin with sulfur atoms using thiourea compound. In the substitution reaction, the conversion of oxirane ring to thiirane ring could be controlled by changing the reaction time. The episulfide resins obtained were cured with 1,3-Bis(aminomethyl)cyclohexane. Thus, the transparent cured episulfide resins which have high refractive index (n_d > 1.61) and relatively low birefringence were obtained. The episulfide resins in which the contents of thiirane rings are 70 and 90% formed phase separation in their curing process. These phase separated resins also have high transparency in the visible right region. In addition, these resins showed high tensile fracture energy caused by the stress distribution which arises from the phase separation structure.

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In this paper the characteristics of filler for thermosetting plastics and rubbers were introduced. The effect of the filler/polymer interface structure and dispersion state of fillers on the properties of composite was discussed.

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The influences of alkoxy group number and loading method of silane coupling agents on the mechanical properties of a styrene-butadiene rubber/silica composite were reviewed. The pre-treatment method and the integral blend method were compared. In the case of mercapto-functional silane, the 200% modulus was higher in the pre-treatment than in the integral blend for dialkoxy type. However, it was higher in the integral blend than in the pre-treatment for trialkoxy type. The binding of rubber molecular chains by the silane chains on the silica surface was higher in the pre-treatment for dialkoxy type, whereas it was higher in the integral blend for trialkoxy type. In the pre-treatment for dialkoxy type, a linear silane chain formed in the case of multi-layer coverage. The silane chain entangled with the rubber chain and improved the reinforcement effect. In the integral blend for trialkoxy type, the formation of the silane network and the entanglement progressed simultaneously during the preparation process. A well entangled interfacial region was formed. The ¹H pulse nuclear magnetic resonance spectroscopy was measured for the unvulcanized rubber/silica mixture. The measured relaxation time was found to be in good correlation with the 200% modulus.

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