Katsuhiko Takaya

Anionic polymerization of p-methoxystyrene in tetrahydrofuran

Kinetics of homopropagation of living poly-p-methoxystyrene has been investigated in tetra-hydrofuran at 25°C in the presence and absence of an electric field. The rate constants of ion pairs were evaluated to be 40, 40 and 15 M–1 s–1 for sodium, potassium and caesium salts, respectively, being smaller than those for the corresponding salts of living polystryene. The rate constant of free anion was 4.0 × 104 M–1 s–1, and was also smaller than that for styrene. The difference between the rate constants of these two monomers was attributed to the difference of the reactivities of the monomers due to and electron-donating effect of the methoxy group. The dissociation constants were also smaller than those of the living polystyrene. This is due to the interaction between the active end and gegenion becoming larger as a result of an increase of the electron density at the active end by the methoxy group. The substituent effect was notable especially for the dissociation behaviour of ion pairs containing gegenions of small ionic radius. The comparatively large field effect was observed at lower field intensities than for styrene previously studied.

Ionic polymerization under an electric field. Part 15.—Anionic polymerization of styrene in tetrahydropyran

“Living” anionic polymerizations of lithium, sodium, potassium, and caesium salts of polystyryl anions were investigated in tetrahydropyran at 25°C in the presence and absence of an electric field. The field increased the k″pK½ term, except for the caesium salt; k″p is the free ion rate constant and K the dissociation constant of ion pairs. From the conductivity data, the field effect was concluded to be due to an increase in k″p with increase of the field. For the sodium and potassium salts, k″p reached a limiting value (≈ 1.2 × 105 M–1 s–1) above 3kV/cm, which was attributed to desolvated free ions. The ion-pair rate constants were 10, 13, 61 and 64 for lithium, sodium, potassium and caesium salts, respectively, and were not influenced by the electric field. The small k″p values of the lithium salt in the absence of the field and its large field effect are discussed.

Anionic polymerization of styrene in 2-methyltetrahydrofuran

“Living” anionic polymerizations of lithium, sodium, potassium, and caesium salts of polystyrylanions were investigated in 2-methyltetrahydrofuran at 25°C in the presence and absence of an electric field. The field increased the k″pK″½ term; k″p is the free ion rate constant and K the dissociation constant of ion pairs. The K values of all four salts were determined from conductivity data, and the free ion rate constant was 7 × 104 M–1 s–1. From the conductivity data, the field effect was concluded to be primarily due to an increase in k″p with increase of the field strength. The k″p reached a limiting value of ≈ 1.2 × 105 M–1 s–1 above 3 kV/cm, which was virtually the same as those found in tetrahydropyran and in binary mixtures of benzene and tetrahydrofuran. The increase in k″p was attributed to desolvation of solvent molecules weakly bound to free carbanion. The ion pair rate constants k′p were 25, 23, 17 and 23 M–1 s–1 for Li+, Na+, K+ and Cs+ salts, respectively, and were not affected by the electric field.

Kinetics of anionic polymerization of styrene in binary mixtures of dimethoxyethane and benzene

The kinetics of anionic polymerization of polystyryl salts with various gegen ions have been investigated spectrophotometrically in 1,2-dimethoxyethane (DME)+ benzene mixtures at 25°C. The behaviour of two types of polymers, viz. one- and two-ended polymers, was studied for sodium and caesium salts. The two-ended sodium salt is as reactive as the one-ended salt, whereas the two-ended caesium salt is less reactive than the one-ended salt. The conductance of the two-ended sodium salt is smaller than that of the one-ended, whereas the conductance of the two-ended caesium salt is larger than that of the one-ended salt. The ion-pair rate constants k′p in the DME + benzene (50 : 50) mixture are 360, 182 and 90 dm3 mol–1 s–1 for the sodium, potassium and caesium salts. The dissociation constants K are 4.7 × 10–10, 1.3 × 10–10 and 3.5 × 10–12 mol dm–3 for the sodium, potassium and caesium salts. The free ion rate constant k″p is 9–10 × 104 dm3 mol–1 s–1 for these salts. The contribution of the intra-molecular triple-ion was observed for the two-ended living polystyrene and the rate constant k″′p(c) of this ionic species is ∼1000 dm3 mol–1 s–1, practically independent of solvent, and is smaller than the rate constant of the solvent-separated intermolecular triple ion (kt′p∼1.2 × 105 dm3 mol–1 s–1).

Anionic polymerization of styrene in binary mixtures of 1,2-dimethoxyethane and benzene

The kinetics of living anionic polymerizations of styrene has been studied with lithium as gegenion in solution in binary mixtures of 1,2-dimethoxyethane and benzene at 0, 25 and 35°C. The contribution of intermolecular triple ions is suggested from kinetic and conductivity data. The dissociation constant of the ion pairs increases as the temperature is lowered, while that of the triple ions decreases. Both the ion-pair and triple-ion dissociation constants increase as the dielectric constant is increased. The rate constants for the ion pairs, free ions and triple ions were determined. The triple ions are suggested to be of a solvent-separated intermolecular type and to be much more reactive than the free ions. No effect of electric field on the kinetics was observed in this system.

Synthesis of poly(hydroxymethylene-co-ethylene) by hydrogenation of the ethylene and carbon monoxide copolymer obtained by radical initiator with Ru/α-alumina and oxygen gas permeability

A new polymer (polyalcohol) was synthesized by hydrogenation of an ethylene carbon monoxide (CO) copolymer produced by a radical method with a catalyst and H2. The Ru/α-alumina catalyst systems showed an excellent activity for hydrogenation of the radical copolymer of CH2CH2 and CO. Films prepared by melting and pressing the synthesized polyalcohol had a high gas barrier property and high tensile modulus. This new polymer has hydroxymethylenic units [CH(OH)] and ethylenic units [CH2CH2] in its molecular structure. The new functional polymer poly(hydroxymethylene-co-ethylene), [CH(OH)]n[CH2CH2]m, is amorphous and has excellent and important properties as a high oxygen gas barrier film for wrapping and storage. This may be attributed to the new structure of poly(hydroxymethylene-co-ethylene) (PHME as an IUPAC name), or ethylene methine alcohol copolymer (EMOH as a generic name), compared to the other ethylene vinyl alcohol copolymer (EVOH as a generic name), [CH2CH2]m[CH2CH(OH)]n, which is used as one of the highest gas barrier polymers.