Yoshio Terawaki

Stereocomplex formation between isotactic PMMA and syndiotactic polymethacrylates in bulk and in solution

SummaryBlend of isotactic PMMA and syndiotactic poly(benzyl methacrylate) was found to form stereocomplex when annealed at 80°C. The blend showed endotherm in DSC thermogram due to the melting of the complex. The complex was also formed in toluene, which was evidenced by1H NMR spectroscopy and thermal analysis. Several syndiotactic polymers of substituted benzyl methacrylates and aliphatic methacrylates having primary alkyl ester group with branching at β-position, such as methallyl and cyclopropylmethyl methacrylates, were also found to form stereocomplexes with isotactic PMMA in bulk by annealing.

Studies on the water in cellulose acetate membranes by high resolution 1H NMR spectroscopy

SummaryHigh resolution 1H NMR spectra of asymmetric and dense membranes of cellulose acetate were measured after immersing them in water, and two water peaks were observed. The upfield small peak was assigned to the bound water and the other to the free water. 1H-T1 of the bound water was shorter than that of the free water. The bound water in the dense membrane is more strongly associated with the cellulose acetate surface than in the asymmetric membrane. The results were discussed in terms of the nature of the interaction forces working in water molecules and the properties of waters induced by such interaction forces.

Studies on the radical polymerization of vinyl acetate in benzene, chlorobenzene and ethyl acetate by 1H NMR spectroscopy

SummaryPolymerizations of vinyl acetate were carried out with AIBN in benzene, chlorobenzene and ethyl acetate, and the resultant polymers were analyzed for terminal group by using 1H NMR technique. The results revealed that a part of the polymer molecules prepared in aromatic solvent contained one solvent fragment at the chain end, indicating the incorporation of aromatic molecule through the chain transfer reaction and not by the copolymerization. It was found that there existed at least 0.7 branching per a molecule in the polymer prepared in ethyl acetate, whereas almost no branching in the polymer prepared in aromatic solvents.

Structural dependence of carbon-13 NMR spin-lattice relaxation times of 1,4-polyisoprenes

SummaryCarbon-13 spin-lattice relaxation times, T1s, were measured for cis-1,4, trans-1,4 and cis-trans isomerized polyisoprenes in chloroform-d1 at 25 MHz and mainly at 27°C. Cis-polyisoprene generally showed longer T1 than the trans-polymer except for methyl carbon, showing the greater segmental mobility of cis-polymer chain. The T1 of methyl carbon was longer for the trans-polymer than for the cis-polymer. This indicates the greater freedom of the internal rotation of methyl group in trans-polyisoprene. The segmental motion was found not to be isotropic, especially for cis-polyisoprene. The T1s of the main chain carbons in cis-trans isomerized polyisoprenes increased with increasing content of the cis-unit.