聚酰胺——聚对苯二甲酰对苯二胺的研究

详细地研究了对苯二甲酰-对苯二胺低温溶液缩聚时,各种反应条件对聚合体分子量的影响,获得了适合于液晶纺丝的高分子量聚合体,其η_(inh)可达5—7。结果表明,聚合体系的水份、单体克分子浓度、各种混合溶剂体系比对聚合体分子量有明显的影响。为获得高分子量聚合体,混合溶剂体系的最佳组成分别为:HMPA:DMAC=4:1(体积比)、HMPA:NMP=7:3 和 HMPA:THF=9:1。当水份含量大于100ppm时,将严重妨碍高分子量聚合体的得到。在缩聚反应初期,聚合体η_(inh)随时间迅速增长,两三分钟内出现凝聚现象,聚合转化率达100％。体系凝聚后缩聚反应仍然进行,聚合体仍有增长。     

Sequence distribution of repeating units of copolyamides by interfacial or solution methods

The sequence distribution of repeating units of copolyamides from different diamines with isophthaloyl or terephthaloyl chlorides and dithiophenyl adipate have been investigated either by interfacial or solution methods to aim at the sequence control of the copolyamides by solvents. Copolycondensation of dithiophenyl adipate and isophthaloyl chloride with m-xylylenediamine in various solvents yielded copolyamides having different compositions of repeating units. Aprotic polar solvents produced random copolyamides having the same compositions as feed ratios of the comonomers, while nonpolar solvents yielded copolyamides rich in isophthaloyl units. Also the sequence distribution of the copolyamides from m- and p-phenylenediamines with isophthaloyl chloride was affected by solvents; nonpolar solvents produced copolyamides having a less-random and block character of the repeating units either by interfacial or solution methods.     

Study on wholly aromatic polyamides containing methyl-substituted phenylene linkage

In order to study the influence of chemical modification on properties of polyamides, wholly aromatic polyamides have been synthesized from p-phenylenediamine, its 2,5-dimethyl and 2-methyl derivatives, m-phenylenediamine, its 2-methyl and 4-methyl derivatives, and terephthaloyl and isophthaloyl dichlorides by solution polycondensation at low temperature. The thermal stability and solubility of the methyl-substituted polyamides were compared with those of unsubstituted ones. The introduction of methyl groups in a polymeric chain led to a decrease in their thermal stability to different degrees depending on the positions of methyl groups, accompanied by an increase in their solubility. The unsymmetrical introduction of methyl groups in benzene rings had a greater effect on the increase in solubility of polyamide than did symmetrical methyl groups.     

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.     

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.     

Soluble aromatic polyamide bearing ether linkages: synthesis and characterization

Soluble aromatic polyamide chains were prepared by reacting 4–4′-oxydianiline with isophthaloyl chloride in dimethylacetamide. To quench the HCl produced during the polymerization reaction, a stoichiometric amount of triethylamine was added. The precipitates formed were separated leaving behind clear polyamide resin. Thin and transparent film was obtained by evaporating the solvent and was subjected for Fourier transform infrared (IR), nuclear magnetic resonance (NMR), gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, water absorption, and mechanical analyses. The transparent film was found to be soluble in dimethylacetamide, dimethyl sulfoxide, and dimethylformamide. IR and NMR spectroscopic analyses confirmed the structure of the polyamide while the gel permeation chromatography revealed the formation of a high-molecular-weight polymer. Thermogravimetry, differential scanning calorimetry, water absorption, and mechanical testing were also performed to further verify its physical properties. A soluble aromatic polyamide was successfully synthesized by solution polymerization and characterized. The polyamide has film-forming property, and the film is transparent, mechanically strong, and thermally stable.     

Polyquinazolotriazoles

A novel high molecular weight (η_inh = 1.4 dl/g) polyquinazolotriazole (PQT) was prepared from the reaction of 3,3′-(2″,6″-pyridinediyl)bis[5-(o-aminophenyl)-1,2,4-triazole] with isophthalic acid by solution cyclopolycondensation in polyphosphoric acid, with diphenyl isophthalate by melt polycondensation, and with isophthaloyl chloride to form a precursor polyamide which subsequently underway cyclodehydration. Thermal characterization of the PQT by thermogravimetric analysis showed initial weight loss in air commencing at ～490°C. The PQT exhibited a weight loss of only 4% after aging in static air for 200 hr at 316°C and a T_g of 342°C as measured by differential scanning calorimetry. Prior to polymer synthesis, a series of model compounds was prepared as a guide to polymer synthesis and identification.     

Synthesis of 3-(4-Oxo-4H-3,1-benzoxazin-2-yl)-1-benzenesulfonyl Chloride and Its Reactivity toward Amines

3-(4-Oxo-4H-3,1-benzoxazin-2-yl)-1-benzenesulfonyl chloride was synthesized, and reactivity of its functional groups was studied. Reactions of the title compound with equimolar amounts of aniline and piperidine gave the corresponding sulfonamides with retention of the benzoxazine moiety. The same reactions with excess amine resulted in opening of the oxazine ring and formation of o-(m-aminosulfonylbenzoylamino)benzamides.     

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.     

Preparation and properties of polyesters and copolyesters based on 4-methyl-2,4-bis (p-hydroxyphenyl)-1-pentene

4-Methyl-2,4-bis (p-hydroxyphenyl)-1-pentene (MBHPP) was prepared from thermal cracking of bisphenol A (BPA). Unsaturated polyesters were synthesized from the polycondensation of MBHPP with diacid chlorides. Three synthetic routes—solution, interfacial, and melt polycondensation—were employed. MBHPP-polyesters with higher molecular weights were obtained by the interfacial polycondensation reaction. During the preparation of MBHPP-polysters, the products usually contain some insoluble gel, which is probably caused by the crosslinking reaction of the vinyl groups of MBHPP in the aqueous NaOH. Thus, a modified interfacial polycondensation method was proposed, in which both of the bisphenol MBHPP and diacid chloride were dissolved in organic phase and then the solution was stirred with an aqueous NaOH solution to promote the polycondensation. This method reduced the time of MBHPP present in the alkali and produced polymers with higher inherent viscosity and lower gel fraction. The effects of some variables, such as the nature of porganic solvents and phase transfer agents and the concentration of reactants, on the modified interfacial polycondensation of MBHPP with the mixture of equal parts of isophthaloyl and terephthaloyl chloride [IPC/TPC (50/50)] were investigated in some detail. Copolyesters of mixed bisphenols of BPA/MBHPP with IPC/TPC (50/50) were also prepared and characterized.     

Aromatic polyethers,polysulfones, and polyketones as laminating resins

m-Hexaphenyl ether, diphenyl ether, and 1,3-bis(p-phenoxybenzenesulfonyl)benzene were polymerized with isophthaloyl and terephthaloyl chloride in a Friedel-Crafts type polymerization. The polymers were endcapped with p-cyanobenzyl chloride or had units of 5-cyanoisophthaloyl chloride in the backbone. They were crosslinked effectively, possibly by the trimerization of the nitrile groups to triazines. Model reactions were carried out for each type of polymer.     

Synthesis and characterization of polyarylates derived from 4,4′-dihydroxy-meta-terphenyl and aromatic diacid chlorides

Polyarylates derived from 4,4″-dihydroxy-meta-terphenyl (DHmTP) were prepared by the phase-transfer catalyzed, two-phase polycondensation with aromatic diacid chlorides. The resulting polymers were crystalline, solvent resistant, and produced brittle films. Copolymers with bisphenol-A were also synthesized using isophthaloyl diacid chloride. At low to moderate levels of DHmTP in the copolymers (25–75%), the materials had high glass transition temperatures (186–201°C), good solvent resistance, and gave tough, clear films. Terpolymers of DHmTP and BPA with 50:50 isophthaloyl and terphthaloyl diacid chloride were prepared with not much improvement over Ardel D-100®. All the DHmTP-polyarylates had good thermal stability (5% weight loss in air > 415–460°C) and had a high % char (20–48%). © 1994 John Wiley & Sons, Inc.     

Room-temperature polycondensation of β-amino acid derivatives,I. Polyamide from amino alcohols and acrylates

Acrylates, such as ethyl acrylate, add with amino alcohol to form N-(hydroxyalkyl) β-alanine ester and room-temperature polycondensation follows, forming polyamide in the presence of a basic catalysts, such as alkali metal alkoxide. The reaction medium has an influence on the course of the polycondensation; that is, N-(hydroxyalkyl) polyamide is formed in methanol solution and polyamide ether in other solvents, such as tetrahydrofuran. These two courses of the room-temperature polycondensation have been studied, and the reaction mechanism is discussed in this paper.     

Crosslinked polyamide based on main‐chain type polybenzoxazines derived from a primary amine‐functionalized benzoxazine monomer

Two types of main‐chain type polybenzoxazines with amide and benzoxazine groups as repeating units in the main chain, termed as poly(amide‐benzoxazine), have been synthesized. They have been prepared by polycondensation reaction of primary amine‐bifunctional benzoxazine with adipoyl and isophthaloyl dichloride using dimethylacetamide as solvent. Additionally, a model reaction is designed from the reaction of 3,3′‐(4,4′‐methylenebis(4,1‐phenylene))bis(3,4‐dihydro‐2H‐benzo[e][1,3]oxazin‐6‐amine) with benzoyl chloride. The structures of model compound and polyamides are confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopies. Differential scanning calorimetry and FTIR are also used to study crosslinking behavior of both the model compound and polymers. Thermal properties of the crosslinked polymers are also studied by thermogravimetric analysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Wholly aromatic polyamide-hydrazides. IV. Structure–property relationships for polymers containing p-phenylene and m-phenylene units

A series of wholly aromatic polyamide-hydrazides was investigated in order to acquire clear understanding of the influence exerted by controlled structural variations in these polymers upon some of important properties, such as chain flexibility, membrane permselectivity, and thermal as well as thermo-oxidative stability. For that reason, the content of para and meta phenylene units was varied within this series so that the changes in the latter were 12.5 mol % from polymer to polymer, starting from an overall content of 0–50 mol %. The polymers were prepared by a low-temperature solution polycondensation reactin of p-aminobenzhydrazide (ABH) and terephthaloyl chloride (TCI), isophthaloyl chloride (ICI), and their appropriate combinations in N,N-dimethylacetamide (DMA) as solvent and all of these preparations were monitored viscometrically in order to prepare the products with as similar as possible average molecular weights. Polymer structures were characterized by elemental analysis, infrared spectrometry, and ¹³C NMR spectroscopy, while their molecular weights were determined by light scattering and dilute-solution viscometry. Polymer properties were evaluated by solution viscometry, reverse osmosis tests, and thermal gravimetric analysis. The results obtained during the preparation of these materials, their subsequent structural characterization, and their property evaluations are discussed. They clearly indicate that substitution of m-phenylene units for p-phenylene ones within this polymer series led to an increase in polymer chain flexibility (from what is usually referred to as semiflexible or semirigid to typically flexible macromolecules), disrupted selectivity of the asymmetric thin membranes under reverse osmosis conditions and decreased stability at elevated temperatures in inert as well as in oxidative atmospheres.     

Thermal properties and solubility of ordered aromatic polyamides containing a methyl-substituted phenylene linkage

Ordered aromatic polyamides and copolyamides were prepared by the polycondensation of terephthaloyl and isophthaloyl dichlorides with symmetrical diamines containing preformed amide linkages derived from unsymmetrical methyl—substituted aromatic diamines at low temperature. Thermal properties and solubilities of the ordered polyamides were compared with those of the corresponding random polyamides. There was little difference between thermal stabilities of the ordered polyamide and the corresponding random one, while the former was less soluble in organic solvents than the latter, depending on the extent of hydrogen bonding of the amide groups. The thermal stability of the alternating copolyamides containing both terephthaloyl and isophthaloyl groups as acid components was less than that of the corresponding homopolymers having either a terephthaloyl or an isophthaloyl group, and the solubility of the former resembled that of the corresponding ordered homopolysiophthalamides in accord with the extent of hydrogen bonding of the amide groups in both polymers.     

Synthesis of polyesters having quaternary ammonium groups in the side chains and preparation of their blends with poly(vinyl alcohol)

Triethyl-2,3-propanediolammonium chloride (TPC) was prepared and used for the preparation of polyester and copolyesters having quaternary ammonium groups in the side chains. The polycondensation of isophthaloyl dichloride with TPC and other dihydroxy compounds was performed by the organic phase/organic phase interfacial polycondensation method using N,N-dimethylacetamide/n-heptane or trimethyl phosphate/n-heptane as reaction media in the presence of tetramethyl ethylenediamine. Blend films were prepared from these polyesters and poly(vinyl alcohol) by casting from aqueous or aqueous NaOH solution. The electrical conductivity of the blend films is remarkably affected by the moisture content and in the order of 10^?5 ～ 10^?8 S/cm in the presence of moisture. © 1994 John Wiley & Sons, Inc.     

Thermally reactive aromatic polyamides

2,5-Bis(phenylethynyl)terephthaloyl chloride and 4,6-bis-(phenylethynyl)isophthaloyl chloride were synthesized in a multistep reaction scheme from 2,5-dibromoterephthaldehyde and 4,6-dibromoisophthaldehyde, respectively. Low temperature solution polycondensation of these novel monomers and tolane-2,4′-dicarbonyl chloride with aromatic diamines yielded aromatic polyamides containing phenylethynyl moieties. Inherent viscosities of 0.20–0.51 dL/g were recorded. Attempts to carry out the homopolymerization of 2-(3-aminophenylethynyl)benzoyl chloride hydrochloride under similar conditions led to low molecular weight polyamide. Under differential scanning calorimetry and thermal mechanical analysis, the polyamides exhibited strong exotherms with onset occurring in the 185–225°C range. The exotherms were attributable to intramolecular cycloaddition of phenylethynyl moieties with amide groups to give polybenzalphthalimidine structures. Curing of a pressed pellet specimen for 16 h at 250°C under a nitrogen atmosphere resulted in partial conversion to a polybenzalphthalimidine structure with a concomitant increase in the polymer glass transition temperature. Isothermal aging in air of the cured specimen at 316°C (600°F) led to 25% weight loss after 200 h.     

Synthesis of polyester and copolyesters having amino acid moieties in the main chain

N, N-di (2-hydroxyethyl)-3-aminopropionic acid (M3) was synthesized and used for the preparation of a series of polyesters having amino acid moieties in the main chain and carboxyl groups as the side group. Polycondensation of M3 , diols, bisphenol A, and isophthaloyl dichloride were performed in the presence of tertiary amine by solution and interfacial methods. Molecular weights of the polymers obtained by the solution method were not high, because oligomers produced at the early stage of reaction are ionized by H⁺ ions from the by-product, and become nonreactive triethylamine hydrochloride. Polymers with high M?_w (1–10 × 10⁴) were obtained in a high yield by organic/organic two-phase interfacial polycondensation using DMAc and n-heptane as solvents. The combined nucleophilic and basic complex catalytic action of N, N, N′, N′-tetramethyl ethyiene diamine (TEMED) is suggested for the present organic phase/organic phase interfacial polycondensation. This method can be applied for the preparation of novel functional polyesters. © 1994 John Wiley & Sons, Inc.     

Synthesis and liquid crystal properties of bipyridine-containing aromatic polyamides

A series of novel aromatic polyamides containing 2,2′-bipyridine moiety were synthesized by polycondensation of 2,2′-bipyridine-5,5′-dicarboxylic acid ( 2 ) with various aromatic diamines in hexamethylphosphoramide (HMPA) containing lithium chloride. The resulting polyamide solutions in 98% sulfuric acid and in HMPA-LiCl exhibited lyotropic liquid crystal phases. The phase transition behaviors were studied by polarizing microscopy and X-ray diffraction. The polyamides also formed metal complexes with cis-dichlorobis(bipyridine)ruthenium dihydrate [cis-Ru(bpy)₂Cl₂ · 2H₂O] which was supported by changes in electronic spectra.