ChemInform Abstract: Three Lowest-Lying Electronic States of NH2.

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Poly(silamine)s as new electron-beam resist materials

Several types of poly(silamine)s were prepared and their structure-characteristics relationships were investigated. When a phenyl ring in the organosilyl unit and/or a cyclic structure in the amino unit was introduced, the glass transition temperatures were increased significantly in order to increase film formability. From the thermogravimetric analysis of the poly(silamine)s, it was found that the thermal decomposition of poly(silamine)s starts at ca. 380–400°C. On electron-beam irradiation of the poly(silamine) films, degradation of the polymer took place. On the basis of these results, poly(silamine)s can be one of the candidates for new positive-type polymeric resists.     

Synthesis of polyolefins with unique properties by using metallocene-type catalysts

Copolymerization of ethylene and 1,5-hexadiene (HD) by zirconocene catalysts proceeded via cyclization-addition mechanism to form 1,3-didsubstituted cyclopentane structure in the polyethylene chain. The 1,3-cyclopentane structure was found to be taken in the crystalline structure of polyethylene (isomorphism) by partially chainging the trans zigzag chain into gauche conformation, thereby, inducing a transformation of orthorhombic crystal to pseudohexagonal crystal. Copolymerization of ethylene and cyclopentene (CPE) by zirconocene catalysts yielded copolymers having 1,2-disubstituted cyclopentane structure in the polyethylene chain. The 1,2-cyclopentane structure was not taken into the crystalline structure of polyethylene. The melting point (T_m) and the crystallinity (X_c) of polyethylene decreased by copolymerization of HD or CPE, and the T_m- and X_c-decreasing effect of CPE was stronger than HD. For copolymers of propylene and HD or CPE obtained with isospecific zirconocene catalyst, the isomorphism was not ovserved.     

A novel synthesis of semitelechelic functional poly(methacrylate)s through an alcoholate initiated polymerization. Synthesis of poly[2-(N,N-diethylaminoethyl) methacrylate] macromonomer

Potassium alcoholate was found to initiate the anionic polymerization of 2-(N,N-diethylaminoethyl) methacrylate (AMA) to form poly[2-(N,N-diethylaminoethyl) methacrylate] (PAMA). The molecular weight of the polymers was controlled by the monomer-initiator ratio with a narrow molecular weight distribution. Increased reactivity of the initiator by chelation of the monomer to the cation may be important for the polymerization. Using potassium (4-vinylbenzyl) alcoholate as an initiator, PAMA having a vinylbenzyl group was prepared which is a macromonomer having pH sensitive amino groups in each monomeric unit. By radical copolymerization with styrene, the PAMA macromonomer was incorporated as a graft chain.     

Spectroscopic studies of conducting polymers

Electronic and vibrational spectra of poly(p-phenylenevinylene) doped with donors or acceptors have been studied, together with the spectra obtained for the radical ions and divalent ions of its oligomers. The electronic absorption spectra of doped poly(p-phenylenevinylene) in the region from visible to near-infrared show two bands for the H₂SO₄-doped species and one very broad band for the Na-doped species. On the basis of the analyses of resonance Raman spectra, the two electronic absorption bands of the H₂SO₄-doped species are attributed to a polaron-lattice structure, whereas the broad band of the Na-doped species is attributed to overlapping absorptions associated with localized electronic levels of polarons and bipolarons. A Pauli spin susceptibility of the H₂SO₄-doped species is explained by the polaron-lattice structure.