Thermotropic copolyamides from triethylene glycol bis(4-carboxyphenyl) ether and o-tolidine modified by kinking monomers

Copolymers of triethylene glycol bis(4-carboxyphenylether) (PEG₃), 4,4′-diamino-3,3′-dimethylbiphenyl (o-tolidine, OT), and several kinking comonomers of dicarboxylic acids and diamines were prepared to investigate which of the comonomers is more effective to lower melting points (T_ms) and clearing temperatures (T_is) of the resulting thermotropic copolyamides. In general, diamine modifiers were more effective than dicarboxylic acid ones even having the same chemical structures. All of diamines examined depressed their transition temperatures linearly with the modifier content whereas the dicarboxylic acid modifiers yielded copolymers having different profiles. m-Aminobenzoic acid, another type of comonomer producing the polyamide of the AB structure, was also examined. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 363–368, 1999     

Synthesis and properties of liquid crystalline copolyarylates containing phenylhydroquinone

Copolycondensations of TPA, PhHQ, and several aromatic diacid and diol modifiers were examined for which kind of the modifiers incorporated is more effective to reduce the transition temperatures of the resulting copolyesters and how they affect the temperatures. The acid modifiers are more effective than the diol ones, significantly when they have substituents. As another type of modifier, HBA forming the ester bond of an AB structure different from the AABB structure of TPA/PhHQ polyester was also effective, and the lowering effect on the temperatures was varied by the mode of copolycondensations, being most remarkable when HBA was randomly introduced. The results obtained were discussed in terms of the disturbance and thereby weakening of the interchain dipole–dipole interaction between the carbonyl groups in the ester linkages due to the introduction of the diacid modifiers and of HBA having an ester bond of a different directionality. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 621–626, 1999     

Random copolycondensation of isophthalic acid/terephthalic acid with bisphenols by tosyl chloride/dimethylformamide/pyridine in terms of the monomer reactivity ratios of bisphenols

The random copolycondensation of isophthalic acid/terephthalic acid with various combinations of bisphenols (M₁ and M₂) with a tosyl chloride/dimethylformamide/pyridine condensing agent was carried out to investigate the effects of the monomer reactivity ratios, r₁′ and r₂′, on the reaction, like r₁ and r₂ in radical copolymerization. The ratios were calculated from the probabilities of finding an M₂ unit next to an M₁ unit and of finding an M₁ unit next to an M₂ unit, which were determined by an NMR analysis of the resultant copolymers. They were discussed with respect to the inherent viscosities (molecular weights) of the resultant copolymers. There was a fairly good relationship between r₁′ and r₂′ and the inherent viscosity values of the copolymers, indicating that copolycondensation could be facilitated by a combination of bisphenols; the lowering of r₁′ and r₂′ was indicative of random distributions in the copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3908–3915, 2003     

Thermotropic copolyamides from triethyleneglycol bis(4-carboxyphenyl)ether and two kinds of aromatic diamines

Thermotropic copolyamides were prepared from triethyleneglycol bis(4-carboxy-phenyl)ether (PEG₃) and two types of diamines, substituted p-phenylenediamines and 4,4'-diaminodiphenyls, and depression of melting point and isotropization temperature of the copolymers produced were measured as a function of diamine combination. The depression was not practically observed by the combinations of homologous diamines with several kinds and numbers of substituents, but significant by those of the diamines with different lengths of the mesogenic segments, and by the molar ratios of the diamines employed. The effect was discussed in terms of deviation of interchain hydrogen bonding between amide bonds in the main chain. © 1994 John Wiley & Sons, Inc.     

Direct polyesterification by use of phosphorus oxychloride and LiCl in pyridine

The reaction of the N-phosphonium salt of pyridine derived from phosphorus oxychloride in pyridine was successfully used for the preparation of aromatic polyesters with high molecular weight when carried out in the presence of lithium chloride. In the copolycondensations of isophthalic and terephthalic acid with diphenols, the mode of reaction with the diacids was expected to produce several types of the diacid activated intermediates, which might control the sequences of the diacids in the copolymers. The possible variation of the sequences was studied in terms of the mode and copolymer properties such as glass transition temperatures and liquid crystalline transition temperatures. Competitive model reactions were carried out to discuss these relationships. © 1993 John Wiley & Sons, Inc.     

Preparation of polyaryl esters by a new direct polycondensation reaction with arylsulfonyl chlorides in pyridine

Arylsulfonyl chlorides were successfully used as a new condensing agent for the synthesis of polyaryl esters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. High-molecular-weight polymers (M_w = 84,000) were prepared by reacting dicarboxylic acids with the sulfonyl chlorides in pyridine in the presence of LiCI, followed by treating with a pyridine solution of bisphenols. The polycondensation was significantly affected by factors, such as, the kind of arylsulfonyl chlorides, its amount, the conditions of initial reaction of the acids with the sulfonyl chlorides, the amounts of LiCI added, and dropwise addition of bisphenols.     

Thermotropic copolyamides from polyethyleneglycol bis(4-carboxyphenyl)ethers with different oxyethylene units

Copolymerizations of polyethyleneglycol bis(4-carboxyphenyl)ethers (PEG_n) with different n values were found to significantly lower the anisotropic transition temperature (T_m) of the copolymers produced, and the thermotropic copolyamides of thermally more stable nematic phases were obtained. The effect was investigated in terms of PEG_m/PEG_n molar ratios, the number of oxyethylene units, and the even—odd character of the flexible segment. Several modes of copolymerization were carried out to investigate the effect of monomer (PEG_n sequence on T_m. By these copolymerizations thermally stable copolyamides even from p-phenylenic diamines such as methyl-p-phenylenediamine and p-phenylenediamine were obtained. © 1993 John Wiley & Sons, Inc.     

Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N-dimethylformamide in pyridine

A Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M?_w = 78,000) with relatively narrow molecular weight distribution (M?_w/M?_n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (η_inh = 1.73).     

Structural changes in polymers of diethyl succinylsuccinate(1,4-diethoxycarbonyl-2,5-dihydroxy-1,4-cyclohexadiene) with diamines at high temperatures

The structural changes of the polymers having the following structures: at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure: The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction.     

Preparation of aromatic polyesters by direct polycondensation with thionyl chloride in pyridine

Mechanistic features of the reaction with thionyl chloride in pyridine were studied in a model reaction of benzoic acid with p-chlorophenol or aniline. The yields were significantly affected by the amounts of pyridine, favorably by four equivalents, and the nature of pyridine, suggesting that pyridines are not only HCl scavengers, but are also involved in the reaction itself. The reaction was assumed to proceed via a carboxylic sulfinic-anhydride intermediate different from acyl chloride, and the intermediate was found to be not so reactive that it was completely alcoholyzed by the phenol at high temperatures of more than 60°C. The reaction was successfully applied to the preparation of aromatic polyesters of high molecular weights by the direct polycondensation of aromatic dicarboxylic acids and bisphenols in pyridine at 80°C.