Masatoshi Miura

Preparation and properties of polyamides and polyimides from 4,4″-diamino-o-terphenyl

Abstract Polyamides and polyimides having 4,4″- o -terphenyldiyl units in the main chain were synthesized. The polyamides were prepared from 4,4″-diamino- o -terphenyl and aromatic dicarboxylic acids or aromatic dicarbonyl dichlorides. The polyimides were prepared from 4,4″-diamino- o -terphenyl and aromatic tetracarboxylic dianhydrides. Copolyamides and copolyimides were also prepared using 4,4″-diamino- o - and other diamines. The T g values of the polyamides were high (283–298°C). The polyamides were soluble in cyclohexanone and pyridine. The polyimides also possessed high T g values (298–372°C). The solubilities of the polyimides, on the other hand, were poor. The introduction of o -terphenyl units into the main chain of the polyamides led to high thermal stability as well as good solubility.

Preparation of polyamides having 2-phenyl-4,5-imidazolediyl units in the main chain

Abstract Polyamides having 2-phenyl-4,5-imidazolediyl units in the main chain were prepared from 4,4′-2-phenyl-4,5-imidazole)dibenzoic acid and aromatic diamines. Polycondensation by a direct solution method gave high-molecular-weight polymers. The polymers are highly soluble in polar solvents and show high T g (> 290°C) and T d (> 440°C) values. Films were cast from dimethylacetamide or 1-methyl-2-pyrrolidone solutions. Mechanical properties, i.e. tensile strength, elongation at break and tensile modulus, were evaluated.

Synthesis and properties of novel aromatic polyamides containing 2-methyl-4,5-oxazolediyl structure

Abstract Novel aromatic polyamides having 2-methyl-4,5-oxazolediyl units in the main chains were synthesized. The polyamides were prepared from 4,5-di(4-aminophenyl)-2-methyloxazole (DAPMO) and/or 4,4′-[4,5-(2-methyl) oxazole]dibenzoic acid (MODBA) by the direct polycondensation method. The polyamides, the inherent viscosities of which ranged from 0.64 to 1.95 dl g −1 , were obtained almost quantitatively. The polyamides indicated high thermal properties: glass transition temperatures were found in the range between 280 and 354°C, and thermal decomposition temperatures ranged from 376 to 421°C. The polyamides exhibited good solubility in many organic solvents such as m -cresol, N,N -dimethylacetamide, 1-methyl-2-pyrrolidone, N,N -dimethyl formamide and conc. H 2 SO 4 at 2.0% (w/v). All the polyamides showed amorphous nature. The introduction of the zigzag, rigid and polar 2-methyl-4,5-oxazolediyl structure into the main chains of polyamides was effective in improving the solubility without lowering the high thermal properties.

Selective hydrogenation of alkynes by hectorite-intercalated PD[II] complexes

Abstract Hectorite(LHT)-intercalated Pd[II] complex catalysts, [Pd(NH 3 )4] 2+ /LHT and [Pd(PDT) 3 ] 2+ /LHT, were prepared and characterized by XRD and IR measurements. The basal spacings(d 001 ) of [Pd(NH 3 ) 4 ] 2+ /LHT and [Pd(PDT) 3 ] 2+ /LHT were 1.30 nm and 2.21 nm in air, respectively. When the intercalated catalysts were swelled with the DMSO solvent, d 001 became 1.45 nm for [Pd(NH 3 ) 4 ] 2+ /LHT and 2.94 nm for [Pd(PDT) 3 ] 2+ /LHT. These two types of the intercalated Pd[II] complex catalysts were used for hydrogenation of alkynes in DMSO to study the effect of the clearance spacings(= d 001 − 0.96 (nm) for LHT) on their catalytic activities.

Thermally initiated oligomerization of metallic salts of methacrylic acid in solid state

Abstract Thermal oligomerization of metallic salts of methacrylic acid was investigated over the temperature range 150°–240°C in the solid state. Calcium methacrylate gave α-methylene-γ, γ-dimethylglutarate(I) and α-methylene-δ-methyladipate(II) below 190°C, but I was not formed above 210°C. Above 170°C the trimer, 1-nonene-2,5,8-tricarboxylate(IV), was formed. Barium methacrylate gave both I and II above 170°C, and 4-methyl-1-octene-2,4,7-tricarboxylate(III) and IV above 190°C. Due to the oligomer crystals from calcium methacrylate were disordered, but crystals from barium methacrylate were transformed to the oligomer crystal lattice, I was formed not in the amorphous state but in the crystalline state, however, II was formed in both states. From these results the mechanism of the oligomer formation in the solid state was discussed.

Methanol carbonylation catalyzed by polymer-supported rhodium complexes

Abstract Various polymer-supported rodium complexes were prepared using commercially available cation-exchange resins and chelate resins and the catalytic behaviour with respect to methanol carbonylation in the presence of methyl iodide promoter was investigated. RhCl 3 was simply loaded on functionalized chelate resins such as a polyethyleneimine type (CR-20) and a pyrrolidine type (NR 2 ), and on sodium-form sulphonic resins (AMNa and HPNa) by a cation-exchange method in ethanol solution. The catalysts were treated with hydrogen and/or carbon monoxide before use. Low-pressure methanol carbonylation was studied at 373–473 K in a circulating system in the ranges 6.65–25.9 kPa for carbon monoxide and 2.66–11.3 kPa for methanol with methyl iodide. A sulphonic resin-supported rhodium, Rh/AMNa, showed the highest activity and methyl acetate was produced with a maximum selectivity of 82.5%. The reaction rate observed for the CR-20-supported rhodium is approximately first order with respect to methyl iodide and carbon monoxide and 0.5 order in methanol. An IR study of Rh/CR-20 suggests that the active species of rhodium (I) -carbon monoxide is formed after carbon monoxide treatment and an X-ray photo-electron spectroscopic study of Rh/CR-20 showed the formation of rhodium (II) species after hydrogen treatment.

Thermal cross-coupled dimerisation of alkali and alkaline earth metal salts of methacrylic–crotonic acid binary systems in this solid state

Thermal reaction of sodium and potassium salts of methacrylic–crotonic acids in the solid state selectively affords a cross-coupled dimer, dimethyl hex-1-ene-2,4-dicarboxylate.

Thermal dimerization of alkali-metal salts of crotonic acid in the solid state

The thermal reaction of sodium crotonate (Na-crotonate) in the solid state gave a nearly quantitative yield of hex-1-ene-3,4-dicarboxylate (1). Potassium crotonate (K-crotonate), on the other hand, afforded three isomeric dimers, i.e.(1), 4-methylpent-2-ene-3,5-dicarboxylate (2), and 2-methylene-3-methylbutane-1,4-dicarboxylate (3). In the case of Na-crotonate, X-ray analysis suggests the formation of a solid solution crystal during dimerization. K-Crotonate yielded predominantly (3) at the early stage of the reaction at 295 °C with formation of a solid solution crystal. At a higher temperature, i.e. 320 °C, (1) and (3) were gradually converted into (2), resulting in the decay of the crystal structure.

Synthesis and photodegradation of copolyamides containing α-diketone linkage in the main chain

Abstract Copolyamides were prepared from 4,4′-dichloroformylbenzil, adipyldichloride and hexamethylenediamine. The melting points and solubilities of the copolyamides varied with benzil content. The copolyamides were irradiated by u.v. light in solution and in a film. The copolyamide irradiated in solution was still soluble but the copolyamide irradiated in a film was crosslinked. The mechanisms of the photochemical reactions are discussed.

Effectiveness of 4-Vinylphthalic Acid and 4-Vinylphthalic Anhydride on Adhesion to Dentin.

4-ビニルフタル酸 (4-VPA) と4-ビニルフタル酸無水物 (4-VPAN) を合成し, 10-3処理象牙質へのメタクリル酸メチル (MMA) -トリ-n-ブチルボラン (TBB) レジンの接着を向上させるため, 歯質接着促進モノマーとしてこれらをMMAに溶解させてその効果を検討した. 4-VPAでは接着強さは15%の時, 最高値を示し, その値は14.9MPaであった. MMAへの溶解性を向上させた4-VPANでは5.0%で13.9MPaを示し, これ以下の濃度ではほとんどその効果は観察されなかった. 4-VPANの機能性の低さは加水分解速度の遅さに基因していることがわかり, 4-VPANが加水分解されて親水性基が生まれ, 接着に有効に働くのは4-VPAであることが明らかとなった.