Liquid-crystalline polyesters containing alternating alkylene and oxyalkylene spacers

Three new series of thermotropic polyesters were prepared in which the structural units consisted of two p-oxybenzoyl dyads alternately flanked by a polymethylene segment and an oxyethylene oligomer. In each series the length of the oxyethylene residue was fixed (n = 2, 3 or 4) and the length of the alkylene segment was varied (m = 6-10 and 12). Details of the synthesis and characterization of the polymers are reported. The effect of the parity and length of the oxyethylene and polymethylene segments on the incidence of mesophases and on their thermodynamic parameters is stressed. The substitution of methylene groups by oxygen atoms in the polymethylene spacer of a fourth series of polymer analogues completely inhibited the nematogenicity of the polymers incorporating even powerful mesogens such as the p-oxybenzoyl dyads.     

Preparation and properties of aromatic polyamide-esters from aminophenols and aromatic diacid chlorides

Aromatic polyamide-esters of moderately high molecular weight were prepared from various combinations of three aminophenols (m- and p-aminophenol, and 4-(4′-aminophenoxy) phenol) and two aromatic diacid chlorides (isophthaloyl and terephthaloyl) by interfacial polycondensation in a cyclohexanone/water system and two-phase polycondensation in a dichloromethane/water system with phase-transfer catalysts. The solution polycondensation in dichloromethane/N,N-dimethylacetamide was also successful for the production of high-molecular-weight polymers. The solubility of the aromatic polyamide-esters varied markedly with polymer structure. Except for two polyamide-esters derived from terephthaloyl chloride, all the other polymers were almost amorphous. These polymers had glass transition temperatures at around 200°C and showed 10% weight losses at about 400°C in both air and nitrogen atmospheres.     

p-Benzyne

A noble gas matrix at low temperature was used to investigate the photochemical behavior of diacetyl terephthaloyl diperoxide and dipropionyl terephthaloyl diperoxide as well as 1,4-diiodobenzene. All three photoreactions formed small quantities of a compound with IR absorption bands at 725 and 980 cm⁻¹, which disappeared when the matrix was annealed. These bands correspond to the most intense of the calculated bands (B3LYP) for 1,4-didehydrobenzene (p-benzyne) ( 1 ). That decomposition of the peroxides in fact leads to 1 is confirmed by vapor-phase pyrolysis experiments in which (Z)- 2 was obtained in high yield.     

Preparation and properties of N-phenylated aromatic polyamide-esters from anilinophenols and aromatic diacid chlorides

N-Phenylated aromatic polyamide-esters with high molecular weights were synthesized by the high-temperature solution polycondensation in nitrobenzene at 200°C from combinations of m- and p-anilinophenol and isophthaloyl and terephthaloyl chloride. Reaction variables such as monomer concentration, solvent, temperature, and time were studied to optimize the reaction conditions for the preparation of high molecular weight polymers. Some of the N-phenylated aromatic polyamide-esters have glass transition temperatures around 190°C and good solubility in chlorinated and amide solvents. These polymers gave transparent flexible films by solution-casting. Copolymers from p-anilinophenol and the two diacid chlorides were also synthesized and characterized.     

Polymers from 4,4′-thiodiphenol

Polyesters were made with aromatic diacid chlorides and 4,4,-thiodiphenol. Isophthaloyl chloride and/or terephthaloyl chloride were used as acid chlorides alone or together with 5-cyanoisophthaloyl chloride or [2.2]p-cyclophane-3,9-dicarboxylic acid chloride. The latter components were incorporated in order to make the polymers useful for crosslinking. A polyether could be obtained by polycondensation of 2,4-dichloro-benzonitrile and 4,4′-thiodiphenol. The polycondensations were run in nitrobenzene as solvent.     

Synthesis and characterization of novel aromatic polyamides from 3,4-bis(4-aminophenyl)-2,5-diphenylpyrrole and aromatic diacid chlorides

A new polymer-forming monomer, 3,4-bis(4-aminophenyl)-2,5-diphenylpyrrole, was synthesized in three steps starting from 4′-nitrodeoxybenzoin. Tetraphenylpyrrole-containing aromatic polyamides and copolyamides were prepared from the diamine with various aromatic diacid chlorides and from a mixture of the diamine and 4,4′-oxydianiline with terephthaloyl chloride, respectively. The resultant polymers had inherent viscosities in the 0.3–1.8 dL/g range and were generally soluble in various organic solvents including N,N-dimethylacetamide and m-cresol. They have glass transition temperatures in the range of 306–333°C and showed no weight loss below 380°C in both air and nitrogen atmospheres.     

Aromatic Polyamides of 2,6-Naphthalenedicarboxylic Acid

Wholly aromatic polyamides have been prepared by the interfacial polycondensation of 2,6-naphthalenedicarboxylic acid chloride with m-phenylenediamine. Also, copolyamides with isophthaloyl or terephthaloyl chlorides and the naphthalene diacid chloride were synthesized. The resultant polyamides were amorphous or slightly crystalline as determined by x-ray diffraction, had tensile properties characteristic of hard, strong materials, and were more thermally stable than aromatic polyamides prepared solely from benzene diacid chlorides.     

Low‐temperature route to thermoplastic polyamide elastomers

Thermoplastic polyamide elastomers were obtained by polymerization of aminobenzoyl‐substituted telechelics derived from poly(tetrahydrofuran)‐diols (number‐average molecular weight: 1400 or 2000 g mol^?1) with several diacid dichlorides (terephthaloyl dichloride, 4,4′‐biphenyldicarbonyl dichloride, or 2,6‐naphthalenedicarbonyl dichloride) and chlorotrimethylsilane in N,N‐dimethylacetamide at 0–20 °C. The as‐prepared polymers had melting temperatures above 190 °C and exhibited elastic properties at room temperature, as evidenced by dynamic mechanical analysis and stress–strain measurements. The polymer with 2,6‐naphthalenedicarboxamide hard segments had the widest rubbery plateau within the series, the highest extension at break, and good recovery properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1449–1460, 2004     

Design and Synthesis of Aromatic Polyesters Bearing Pendant Clickable Maleimide Groups

A bisphenol bearing pendant maleimide group, namely, N‐maleimidoethyl‐3, 3‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrrolidone (PPH‐MA) was synthesized starting from phenolphthalein. Aromatic (co)polyesters bearing pendant maleimide groups were synthesized from PPH‐MA and aromatic diacid chlorides, namely, isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), and 50:50 mol % mixture of IPC and TPC by low temperature solution polycondensation technique. Copolyesters were also synthesized by polycondensation of different molar proportions of PPH‐MA and bisphenol A with IPC. Inherent viscosities and number‐average molecular weights of aromatic (co)polyesters were in the range of 0.52–0.97 dL/g and 20,200–32,800 g/mol, respectively indicating formation of medium to reasonably high‐molecular‐weight polymers. ¹³C NMR spectral analysis of copolyesters revealed the formation of random copolymers. The 10% weight loss temperature of (co)polyesters was found in the range 470–484 °C, indicating their good thermal stability. A selected aromatic polyester bearing pendant maleimide groups was chemically modified via thiol‐maleimide Michael addition reaction with two representative thiol compounds, namely, 4‐chlorothiophenol and 1‐adamantanethiol to yield post‐modified polymers in a quantitative manner. Additionally, it was demonstrated that polyester containing pendant maleimide groups could be used to form insoluble crosslinked gel in the presence of a multifunctional thiol crosslinker. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 630–640     

Configurational statistics of poly(ethylene terephthalate) chains

The length of the span of the terephthaloyl residue in poly(ethylene terephthalate) guarantees independence of the conformations of successive repeating units of the chain. Interactions within units of the chain are amenable to interpretation by comparisons with related polymers; cis and trans conformations of the terephthaloyl residue are given equal weighting. The mean-square dimension ratio (〈r²〉₀/M)_∞ estimated on this basis is in substantial accord with the value deduced from experiments.     

基于1,2-二氢-2-(4-羧基苯基-4-[4-(4-羧基苯氧基)-3-甲基苯基](2H)二氮杂萘-1-酮的新型芳香聚酰胺的简易合成

A new monomer diacid, 1,2-dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)-3-methylphenyl]phtha-lazin-1-one (3), was synthesized through the aromatic nucleophilic substitution reaction of a readily available unsymmetrical phthalazinone 1 bisphenol-like with p-chlorobenzonitrile in the presence of potassium carbonate in N,N-dimethylacetamide and alkaline hydrolysis. The diacid could be directly polymerized with various aromatic diamines 4a-4e using triphenyl phosphite and pyridine as condensing agents to give five new aromatic poly(ether amide)s 5a-5e containing the kink non-coplanar heterocyclic units with inherent viscosities of 1.30-1.54 dL/g.The polymers were readily soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethyl-acetamide (DMA), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), and even in m-cresol and pyridine (Py). The transparent, flexible and tough films could be formed by solution casting. The glass transition tem-peratures Tg were in the range of 286-317℃.     

Polyaromatic ether-sulfone-ketones with fluorosubstituted p-cyclophane units as crosslinking sites

Polyaromatic either-sulfone-ketones containing fluoro-substituted p-cyclophane units were prepared from isophthaloyl chloride, terephthaloyl chloride, diphenyl ether, diphenoxydiphenyl sulfone, and a small amount of 1,1,2,2,9,9,10,10-octafluoro-[2,2]-p-cyclophane (type A) or pseudo-p-1,12,2,9,9,10,10-octafluoro-[2,2]-p-cyclophane bis-acid chloride (type B) by Friedel-Crafts-type polymerization. The p-cyclophane units were incorporated as crosslinking sites. Crosslinking was achieved by curing polymers at 300–350°C for several days. The polymers obtained, containing 1–10 wt % fluoro-substituted p-cyclophane units, were moderately soluble in dichloromethane, DMF, and sulfuric acid with inherent viscosities between 0.4 and 0.6. Laminates on glass fiber were made with excellent thermal stability.     

Chiral liquid-crystalline polymers. XI. Thermotropic behavior and chiroptical properties in solution of a new series of optically active poly (ester β-sulfide)s

The synthesis and characterization are described of a series of optically active semiflexible poly(ester β-sulfide)s 6*Sn with repeating units constituted by two p-oxybenzoyl diads spaced in an alternating fashion by a sulfide-containing polymethylene segment of variable length (n = 2-10) and a chiral (R)-3-methylhexanediyl segment of high enantiomeric purity. The polymers were prepared with good yields and relatively high molecular weights and narrow degrees of dispersity by a Michael-type polyaddition reaction of bis-thiols to the same chiral mesogenic bisacrylate monomer. Data are reported on the characterization of their chiroptical properties in dilute solution and thermal-optical properties in the bulk, with attention being devoted to the distinct odd-even alternations of the cholesteric-isotropic melt transition parameters. A comparison of the mesomorphic behavior and relevant thermodynamic quantities is presented between the present series of polymers and the achiral analogues of series 6Sn as well as the chiral, positional isomers of series mS6* . The dependence of the overall properties and their trends on very subtle structural changes is stressed, thus highlighting the critical interconnection between mesogenic cores and spacer segments in semiflexible liquid-crystalline polyesters.     

Synthesis and properties of poly(p‐phenylene terephthalamide) bearing both polar and unsaturated substituents introduced via claisen rearrangement reaction

A series of novel wholly aromatic copolyamides, poly(p‐phenylene terephthalamide)‐ran‐poly[p‐phenylene 2,5‐bis(allyloxy)terephthalamide] (APPTA‐x, x (=0, 5, 25, 50, 60, 75, 90, and 100) represents the molar fraction of allyloxy containing structure unit), were prepared via low temperature solution copolycondensation of p‐phenylenediamine, terephthaloyl chloride, and 2,5‐bis(allyloxy)terephthaloyl chloride. They were converted to the target copolymers, poly(p‐phenylene terephthalamide)‐ran‐poly[p‐phenylene 2,5‐diallyl?3,6‐dihydroxyterephthalamide] (CRPPTA‐x), through Claisen rearrangement reaction, as characterized by a comprehensive analyses of NMR, FT‐IR, gel permeation chromatography, and differential scanning calorimetry. Although APPTA‐x had a poor solubility in common organic solvents, the rearranged products with high co‐unit contents, that is, CRPPTA‐60, 75, 90, and 100, were readily dissolved in m‐cresol, DMF, DMAc, DMSO, and NMP. The effect of these four polymers, used as sizing agents, on the interfacial adhesion between Kevlar fiber and epoxy resin was investigated by the contact angle method, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and microbond tests. Compared with the naked fibers, the sized fibers displayed enhanced surface energy and roughness. The fibers sized with 0.5 wt % CRPPTA‐60 solution in NMP exhibited a maximum increase of 19% in interfacial shear strength. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2050–2059     

Thermotropic aromatic copolyesters of catechol

Three new series of thermotropic aromatic main-chain polymers were synthesized and studied by differential scanning calorimetry and hot-stage polarized microscopy. The polymers were random copolyesters of p-hydroxybenzoic acid (from 60 to 10 mol %), catechol (from 20 to 45 mol %), and one of the following dicarboxylic diacids: terephthalic acid (series 1 ), 2,6-naphtalenedicarboxylic acid (series 2 ), and 1,2-bis-p-carboxyphenoxy ethane (series 3 ). Copolyesters with more than 25 mol % catechol in their structures were soluble in common organic solvents such as chloroform. All the synthesized copolyesters showed hysteresis of the heat capacity at the mesophase glass transition region and nematic mesophases above their T_g's which were stable over very broad ranges of temperature. Copolyesters containing the 2,6-naphtylenedioyl group showed the most stable nematic phases due to the increased anisometry of the 2,6-naphtylenedioyl unit compared to that of the therephthaloyl or the 4-oxybenzoyl units. © 1992 John Wiley & Sons, Inc.     

Synthesis of ordered copolyamides by the interfacial polycondensation of the hydrolyzate of bisimidazoline with diacid chloride

Ordered copolyamides were prepared by the interfacial polycondensation of the hydrolyzate of bisimidazoline in the aqueous solution with diacid chloride in chloroform solution; bisimidazolines used were 1,4-bis(imidazoline-2-yl)butane and 1,4-bis(imidazoline-2-yl)-octane; diacid chlorides used were adipoyl chloride, sebacoyl chloride, and terephthaloyl chloride. The aqueous solutions of the hydrolyzates of bisimidazolines were prepared by heating the aqueous solutions of imidazolines at 70°C. It was shown by infrared spectra and paper electrophoresis of the hydrolyzates that bisimidazolines were hydrolyzed to give quantitatively diamines containing amides linkages of the type H₂N(CH₂)₂NH-CORCONH(CH₂)₂NH₂. The regularity in the sequence of the copolyamide of nylon 26 and nylon 2T prepared from the hydrolyzate of 1,4-bis(imidazoline-2-yl)butane and terephthaloyl chloride was studied by NMR spectrometry: it was concluded that the copolyamide was highly ordered.     

Copolymers of phenylacetylene and para‐nitrophenylacetylene with nonlinear optical properties: Further insight on the conformational structure

Copolymers of phenylacetylene (PA) and para‐nitrophenylacetylene (pNPA), named poly(PA‐co‐pNPA), were obtained in different PA/pNPA ratios and different reaction conditions with Rh(I) catalysts. The structure of the copolymers was investigated with IR, laser Raman, ¹H NMR, electron spin resonance (ESR), and diffuse reflective ultraviolet–visible (DRUV) light spectroscopies. The pristine polymers had a cis–transoidal structure as the predominant conformation with some trans sequences. Detailed ESR studies supported by computer simulation and conformation analysis have suggested that the trans sequences were due to pNPA sequences and that the cis‐C?C bond sequences of pNPA were associated with a stabilized cis radical formed by four to five of pNPA monomers. This particular stabilization was probably the reason for the higher reactivity of pNPA as compared with PA. These cis sequences were preferentially cleaved to generate π radicals. The compression and, to a minor extent, thermal treatment of poly(PA‐co‐pNPA) samples induced a cis‐to‐trans isomerization, leading to a trans–transoidal form with a planar zigzag structure and with a conjugation length up to n = 24 repeat units, determined by DRUV and Raman experiments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2365–2376, 2004     

Aromatic polyethers,polysulfones, and polyketones as laminating resins. V. Polymers containing acetylenic side groups

1,3-Bis(p-phenoxybenzenesulfonyl)benzene and 4,4′-diphenoxydiphenyl sulfone were polymerized with isophthaloyl and terephthaloyl chloride in Friedel-Crafts type polymerizations. These polymers had 2,4-diphenoxyacetophenone in the backbone. The acetyl group was then converted into an acetylene group. They were crosslinked effectively by cyclization of the acetylene groups with a catalyst or by cyclo-addition with bisnitrile oxides.     

Synthesis of optically active poly(amide‐imide)s derived from N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L‐leucine diacid chloride and aromatic diamines by microwave radiation

3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (4,4′‐carbonyldiphathalic anhydride) was reacted with L ‐leucine in a mixture of acetic acid and pyridine (3 : 2), and the resulting imide‐acid [N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L ‐leucine diacid] was obtained in quantitative yield. The compound was converted to the N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L ‐leucine diacid chloride by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride with several aromatic diamines such as 4,4′‐diaminodiphenyl methane, 2,4‐diaminotoluene, 4,4′‐sulfonyldianiline, p‐phenylenedi‐amine, 4,4′‐diaminodiphenylether, and m‐phenylenediamine was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as O‐cresol. The polymerization reactions proceeded rapidly compared with the conventional solution polycondensation and were completed within 6 min, producing a series of optically active poly(amide‐imide)s with a high yield and an inherent viscosity of 0.37–0.57 dL/g. All of the above polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of these optically active poly(amide‐imide)s are reported. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 177–186, 2001     

Synthesis,Characterization and Properties of Novel Poly(Ester-Amide-Urethane)s

A diacid (TOBA) containing an ester group was synthesized by reaction of terephthaloyl chloride with 4-hydroxybenzoic acid. Reaction of the obtained diacid with thionyl chloride resulted in preparation of the related diacid chloride (TOBC). Nucleophilic substitution reaction of 4-aminophenol and also 5-amino-l-naphthol with the prepared diacid chloride afforded two aromatic diols containing ester and amide groups, respectively. Aromatic and semi-aromatic poly(ester-amide-urethane)s were prepared via addition polymerization of different diisocyanates with novel diols. The prepared polyurethanes showed improved thermal stability.