Yuya Yamashita

Copolymer Microstructure by High-Resolution NMR Studies

Abstract The monomer and configurational sequences of several radical copolymers between substituted styrenes and acrylates have been examined by analyzing the high-resolution NMR spectra with the previously reported treatment of the styrene-methyl methacrylate system. The analyses have led to the conclusion that the monomer sequence distribution is just as expected from the usual copolymerization theory with r 1 and r 2.

Synthesis of polyurethane graft copolymers by polyaddition reaction of dihydroxyl-terminated macromonomers

SummaryPolyurethane-poly(methyl methacrylate) graft copolymers of well-defined structure and composition were synthesized by macromonomer method. Dihydroxyl-terminated macromonomer was prepared by radical polymerization of methyl methacrylate in the presence of α-thioglycerol as a chain transfer agent. This dihydroxyl-terminated macromonomer and 1,4-butanediol were added to diisocyanate (hexamethylene diisocyanate or toluene-2,4-diisocyanate) catalyzed by di-n-butyltin dilaurate to produce tailor-made graft copolymers.

Synthesis of well-defined graft copolymer with oligodimethylsiloxane and polyvinylalcohol branches

SummaryPolyvinylalcohol macromer of well controlled molecular weight and molecular weight distribution, whose hydroxyl groups being protected as silyl ethers, was synthesized by Lewis acid catalyzed sequential silyl aldol condensation. Copolymerization of p-oligodimethylsiloxanylstyrene with the macromer, followed by the removal of the hydroxyl protective groups, gave the well-defined title graft copolymer.

Surface Active Properties of Silicone Containing Polymers

SummaryThe efficiency and durability of surface modification of poly(methyl methacrylate) [PMMA] by silicone containing graft and random copolymers were studied by contact angle measurement of water droplet. The efficiency principally depended on the content of the siloxane; however, the durability of surface modification to hexane extraction differed according to the type of the silicone polymer and the siloxane content.

SYNTHESIS OF DICARBOXYLIC ACID FUNCTIONALIZED POLYSILOXANE MACROMERS

SummaryMethods to synthesize aliphatic and aromatic dicarboxylic acid functionalized polydimethylsiloxane macromers were studied. Introduction of allyl group into dicarboxylic acid as a substituent, followed by hydrosilylation by silane terminated polydimethylsiloxane was found satisfactory to obtain the macromers.

Enhancement of oxygen permselectivity of polydimethylsiloxane-b-polycarbonate film by the surface modification with fluorine-containing polymer

SummaryBoth oxygen permeability coefficient(PO2) and separation factor (α = PO2/PN2) through polydimethylsiloxane-b-polycarbonate(PDMS/PC) film were improved by the addition of small amounts(1.0 wt%) of the fluorine-containing polymer. This improvement was considered to be caused by the selective solubilization of oxygen in the surfaceaccumulated fluorine polymer domain.

Convenient synthetic routes to α-oligosiloxanylacrylonitriles

Abstract Novel 1,4-elimination reaction of C,N-bis(trimethylsilyl)-C- trimethylsiloxymethylketenimine and retro Diels-Alder reaction of 2-oligosiloxanyl-5-norbornene-2-carbonitrile cleanly gave α-oligosiloxanylacrylonitriles in excellent yield.

Viscosity and solubilization studies on weak anionic polysoaps in water; Effect of the counter-ion

Abstract Six weak anionic polysoaps with various counter-ions were prepared from a copolymer of maleic anhydride and dodecylvinyl ether. The maleic anhydride unit of the copolymer was either amidated with morpholine and then treated with alkalis to obtain lithium, sodium, potassium, ammonium, and morpholine salt or treated with sodium hydroxide alone to obtain a disodium salt of the polysoap. Viscosity measurements show that the hydration of the counter-ion bound to the chain becomes a significantly important factor for expansion of the polysoap chain, presumably because this interrupts hydrophobic interactions between long alkyl groups in the molecule. The solubilizing power of polysoap toward azobenzene, Orange OT, and Yellow OB did not appear to depend so much upon the nature of the counter-ion except for the ammonium and morpholine salts, which show especially large solubilizing power. However, the absorption maxima of the solubilizates in polysoap solutions as well as the competitive solubilization of the two solubilizates indicate that the ionic groups of the polysoap are also of importance, especially for the location of dye molecules in the polysoap molecule.

Regioselectivity control in alkylation reactions of indolyl ambident anion

The regioselectivity of N- and C-3(β)-alkylations of indolylmetal salts was studied under various conditions. The effect of counter metal ion is crucial in determining the regioselectivity. In tetrahydrofuran, exclusive N-alkylation occurred with the potassium salt, but the extent of C-3-alkylation increased with the sodium and lithium salts and became predominant with the magnesium bromide salt. However, N-alkylation was favoured generally in more polar solvents and for alkyl toluene-P-sulphonates it was favoured even with magnesium bromide salts. The reactivity and regioselectivity of the alkylations were correlated with the calculated electron density of the indolyl anion and with 13C n.m.r. chemical shifts of the metal salts.

Viscosity and solubilization studies on weak anionic polysoaps in nonaqueous solvents

Four anionic polysoaps with different alkyl group lengths and molecular weights were prepared from copolymers of maleic anhydride and dodecyl- or octadecyl vinyl ether by treatment with 2 moles of morpholine. Viscosities and solubilities were measured at 40°C. to show that association between lyophobic groups occurs in nonpolar solvents, in the decreasing order of cyclohexane > benzene > chloroform > tetrahydrofuran. On the other hand, in polar solvents, association occurs between hydrophobic groups in the increasing order of n-butanol < dimethylformamide < water. Alkyl group length exerts a striking influence upon the association and solubility tendency. Solubilization of water brings about a lowering of reduced viscosity of polysoap in nonpolar solvents, indicating that water molecules are incorporated in the interior of the polysoap molecule and contract its chain. The shape of the reduced viscosity vs. water concentration plots, and consequently the extent of solubilization, depends upon the alkyl group length and the solvent used, as expected from solubility behavior. The extent of solubilization amounts to five or six molecules of water per ionic group, in relatively good solvents. Solubilization of water in mixed solvents is favored over that in single solvents.