Synthesis and characterization of polyimides and polyamide-imides containing azomethine linkages

Polyimides and polyamide-imides containing azomethine linkages in the polymer backbone have been synthesized from 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenylether (ODAI), 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenyl-methane (MADI), 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenylsulphone (SDAI), pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), and trimellitic anhydride (TMA), by a one-step process. The diisocyanates ODAI, MDAI and SDAI were prepared from the corresponding diacids, namely, 4,4′-bis(4-carboxybenzylidene)-diaminodiphenylether (ODAA), 4,4′-bis(4-carboxybenzylidene)-diaminodiphenylmethane (MDAA) and 4,4′-bis-(4-carboxybenzylidene)-diaminodiphenylsulphone (SDAA) by a Weinstock-modified Curtius rearrangement method. All the polycondensation reactions were conducted in N-methyl-2-pyrrolidone (NMP) under identical conditions and the polymers obtained were characterized by IR spectroscopy, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction.     

Oxidative degradation of a polyimide film: I. Initial studies

High molecular weight poly-N,N′-(4,4′-diphenylether)pyromellitimide film was prepared from pyromellitic dianhydride and 4,4′-diaminodiphenylether and the oxidative degradation at 400°C was studied by weight loss measurements, infrared spectrometry and saponification experiments. The results indicated the rapid development of crosslinks between the polyimide chains.     

4,4′-二氨基二苯醚合成及精制的新工艺

介绍4,4′-二氨基二苯醚的合成方法,以对硝基氯苯为原料,通过缩合、催化加氢及精制工序制得高品质4,4′-二氨基二苯醚,优化工艺条件后,总收率达到84.5%。该方法具有合成路线先进,工艺简单,产生的"三废"量少,产品纯度高、色泽好等优点。     

Copolyimides new polybenzoxazinone-imides

New polybenzoxazinone-imides have been synthesized by cyclopolycondensation reaction of 4,4′-diaminodiphenylmethane-3,3′-dicarboxylic acid with diacid chlorides containing preformed imide rings. The low temperature solution polycondensation technique, used in these experiments, afforded poly(amic acids) of high molecular weight in the first step, which subsequently underwent thermal cyclodehydration at 200–300°C to give polybenzoxazinone-imides in the second step. The obtained polymers have been characterized by IR absorption, elemental and thermogravimetric analyses. From 10% polymer solution flexible and transparent films have been cast with good mechanical and insulating properties.     

医用HMDI基聚碳酸酯型聚氨酯弹性体的合成与表征

采用熔融预聚物法合成了以4,4′甲烷二环己基二异氰酸酯(HMDI)及1,4丁二醇(BDO)为硬段,聚碳酸酯二醇(PCD)为软段的医用HMDI基聚碳酸酯型聚氨酯弹性体,通过红外光谱、差示扫描量热仪、动态力学热分析仪、凝胶渗透色谱仪、力学性能测试、水解性能测试、细胞毒性测试等表征了其微相分离结构与性能的关系。结果表明,合成的聚碳酸酯型聚氨酯弹性体可浇注成型,避免了致癌降解产物4,4′二苯甲烷二胺(MDA)的生成,具有可调节的力学性能、较好的耐水解性及优异的生物相容性,作为可长期植入体内的生物稳定型医用材料具有良好的应用前景。     

New reverse osmosis membrane materials with higher resistance to chlorine

Copolyamides were prepared from mixed diamine components of 3,3′‐ or 4,4′‐diaminodiphenylsulfone, piperazine, and dichlorides such as isophthaloyl or terephthaloyl. The obtained copolyamides are random copolymers, which have good solubilities in organic solvents and good mechanical properties, even in water. The asymmetric membranes prepared from the copolyamides [ex: 4I‐PIP(20)] not only have more excellent reverse osmosis performance, but also higher chlorine resistance than NOMEX‐type aromatic polyamide. New membrane materials with excellent reverse osmosis performance and higher chlorine resistance than the NOMEX‐type aromatic polyamide could be demonstrated successfully. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1357–1364, 2000     

2,2′,6,6′-Tetrabromo-3,3′,5,5′-tetramethyl-4,4′-biphenol (TTB)–flame retardant copolycarbonates and copolyesters

2,2′,6,6′-Tetrabromo-3,3′,5,5′-tetramethyl-4,4′-biphenol (TTB) is a new flame retardant monomer possessing a high degree of chemical and thermal stability. This brominated biphenol can be directly incorporated as a comonomer in condensation polymerizations. An example is the preparation of copolycarbonates of TTB and 2,2-(4-hydroxyphenyl)propane (BPA) via the aqueous caustic phosgenation method. The reaction of TTB with either ethylene oxide or ethylene chlorohydrin affords 4,4′-bis(2-hydroxyethoxy)-2,2′,6,6′-tetrabromo-3,3′,5,5′-tetramethylbiphenyl (TTB-Diol). This diol is melt polymerized into a series of terephthalate copolymers with 1,4 butanediol. The above copolymers possess flame retardancy, thermal stability, and good mechanical properties. These high-bromine-content copolymers are blended with nonhalogen-containing polymers to afford blends with specific degrees of flame resistance.     

Synthesis and thermal,mechanical and gas permeation properties of aromatic polyimides containing different linkage groups

Two series of aromatic polyimides containing various linkage groups based on 2,7‐bis(4‐aminophenoxy)naphthalene or 3,3′‐dimethyl‐4,4′‐diaminodiphenylmethane and different aromatic dianhydrides, namely 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride), 4,4′‐(hexafluoroisopropylidene)bis(phthalic anhydride), 3,3′,4,4′ benzophenonetetracarboxylic dianhydride, 9,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]fluorene dianhydride and 4,4′‐(4,4′‐hexafluoroisopropylidenediphenoxy)bis(phthalic anhydride), were synthesized and compared with regard to their thermal, mechanical and gas permeation properties. All these polymers showed high thermal stability with initial decomposition temperature in the range 475–525 °C and glass transition temperature between 208 and 286 °C. Also, the polymer films presented good mechanical characteristics with tensile strength in the range 60–91 MPa and storage modulus in the range 1700–2375 MPa. The macromolecular chain packing induced by dianhydride and diamine segments was investigated by examining gas permeation through the polymer films. The relationships between chain mobility and interchain distance and the obtained values for gas permeability are discussed. © 2014 Society of Chemical Industry     

Synthesis and characterization of polyamide-imides

A series of thermally stable, tough, linear polyimides containing amide linkages was prepared. The new polyamide-imides were synthesized by reacting a group of isomers of diaminobenzanilide (DABA) with various dianhydrides, such as 4,4′-oxydiphthalic anhydride (ODPA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The resulting polyamide-acids were thermally or chemically converted to the polyamide-imide (PAI). Twelve polyimides were synthesized from unsubstituted and N-methyl substituted amide diamines and their properties were compared with previously made polyamide-imides and the polyimide LARC-TPI. These polyimides exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films of which some showed good thermal stability and resistance to organic solvents. Overall, the mechanical properties of the PAI films were comparable to those of LARC-TPI with the 4,4′-systems exhibiting exceptional properties and crystallinity. These materials have potential as high temperature films, coatings and fibers, as well as molding and laminating resins.     

Linear polythioesters. IV. The effect of hydrogen chloride acceptor on interfacial polycondensation of 4,4′-di(mercaptomethyl) benzophenone with isomeric phthaloyl chlorides

New polythioesters of better physicochemical and mechanical properties have been obtained by interfacial polycondensation of 4,4′-di(mercaptomethyl)benzophenone with terephthaloyl, isophthaloyl, and phthaloyl chlorides with the use of sodium hydroxide excess as a hydrogen chloride acceptor. According to preliminary experiments, the best yield and the highest reduced viscosity are reached when the polycondensation at a 1:l ratio of the aqueous to the organic phase is carried out at a temperature of 5–7°C with a little excess of acid chloride with addition time of 0.5–2 min in the presence of 100% excess of NaOH as hydrogen chloride acceptor. The structure of the polythioesters was determined from elemental analysis and infrared spectra. Thermal properties of all polythioesters were determined. Mechanical and electrical properties of only the most interesting polythioesters obtained from isophthaloyl chloride were determined.     

Segmented copolyethers with urethane and urea or semicarbazide links for blood circulation systems I. Synthesis and properties

A series of urethane- and urea- or semicarbazide-linked polyethers for biomedical applications were synthesized without the use of a catalyst. Mechanical properties and hydrolyzability of the polymers were investigated. Due to its superior properties, the system poly(oxytetramethylene)diol (POTM)/4,4′-diisocyanatodiphenylmethane (DDM) was studied quite thoroughly. Its resistance against hydrolysis was determined by the molar ratio DDM/POTM and by the kind of chain extender. Polyetherurethane-semicarbazides showed the best mechanical properties, good resistance against hydrolysis and good blood compatibility.     

Synthesis and characterization of aromatic polyesters containing multiple n-alkyl side chains

A series of 2,2′-disubstituted-4,4′-dihydroxybiphenyl monomers was prepared from 3,4,5-tris(n-alkoxy)benzyl chlorides (n = 5, 6, 8, 10, 12) and tetramethylammonium salt of 4,4′-dihydroxydiphenic acid, which was synthesized from two different 5-step routes. 2,2′-Bis(trifluoromethyl)-4,4′-biphenyldicarboxylic acid was synthesized via 5-step route. A series of aromatic polyesters containing multiple alkyl side chains was prepared from the 2,2′-disubstituted-4,4′-dihydroxybiphenyl monomers and 2,2′-bis(trifluoromethyl)-4,4′-biphenyldicarboxylic acid using diisopropylcarbodiimide as a dehydrating agent and 4-(dimethylamino)pyridinium 4-toluenesulfonate as a catalyst at room temperature. Their thermal and solution properties were measured and compared with the polyester without multiple alkyl side chains. The polyesters displayed better solubility in common solvents such as chlorinated solvents and THF but lower thermal stability than the polyester without multiple alkyl side chains. The intrinsic viscosities of the polyesters ranged from 0.68 to 2.53 dL/g and their number-average molecular weights ranged from 19,300 to 61,400. Polyesters containing C5–10 side chains were amorphous while the two polyesters containing C12 side chains crystallized at ?27 and ?31 °C, respectively. The thermal stability of the polyesters decreased as a result of alkyl side chains. The films of polyesters were opaque, indicating that the aromatic backbones and aliphatic side chains underwent phase separation.     

Synthesis and properties of aromatic polyimide,poly(benzoxazole imide), and poly(benzoxazole amide imide)

Two series of heterocyclic aromatic polymers were synthesized from 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthaltic anhydride) and 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride by two‐step method. The inherent viscosities were in the range of 24–45 cm³/g. The effects of the rigid benzoxazole group in the backbone of copolymer on the thermal, mechanical, and physical properties were investigated. These polymers exhibit good thermal stability. The temperatures of 5% weight loss (T₅) of these polymers are in the range of 403–530°C in air and 425–539°C in nitrogen. The chard yields of these polymers are in the range of 15–24% in air and 54–61% in nitrogen. These polymers also have high glass‐transition temperatures and a low coefficient of thermal expansion and good mechanical properties. The poly(benzoxazol imide) has a higher tensile strength and modulus than those of neat polyimide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Glass fiber-reinforced epoxy composites

Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethane

1 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane.

(TGDDM) and tetraglycidyl bis(o-toluidino)-methane

2 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane.

(TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.     

Synthesis and properties of organosoluble polyimides derived from 2,2′‐dibromo‐ and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianilines

Two new aromatic diamines, 2,2′‐dibromo‐4,4′‐oxydianiline (DB‐ODA 4 ) and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianiline (TB‐ODA 5 ), have been synthesized by oxidation, bromination, and reduction of 4,4′‐oxydianiline (4,4′‐ODA). Novel polyimides 6a–f and 7a–f were prepared by reacting DB‐ODA ( 4 ) and TB‐ODA ( 5 ) with several dianhydrides by one‐step method, respectively. The inherent viscosities of these polyimides ranged from 0.31 to 0.99 dL/g (0.5 g/dL, in NMP at 30°C). These polyimides showed enhanced solubilities compared to those derived from 4,4′‐oxydianiline and corresponding dianhydrides. Especially, polyimides 7a , derived from rigid PMDA and TB‐ODA ( 5 ) can also be soluble in THF, DMF, DMAc, DMSO, and NMP. These polyimides also exhibited good thermal stability. Their glass transition temperatures measured by thermal mechanical analysis (TMA) ranged from 251 to 328°C. When the same dianhydrides were used, polyimides 7 containing four bromide substituents had higher glass transition temperatures than polyimides 6 containing two bromide substituents. The effects of incorporating more polarizable bromides on the refractive indices of polyimides were also investigated. The average refractive indices (n_av) measured at 633 nm were from 1.6088 to 1.7072, and the in‐plane/out‐of‐plane birefringences (Δn) were from 0.0098 to 0.0445. It was found that the refractive indices are slightly higher when polyimides contain more bromides. However, this effect is not very obvious. It might be due to loose chain packing resulted from bromide substituents at the 2,2′ and 2,2′,6,6′ positions of the oxydiphenylene moieties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The properties of epoxy–imide resin cured by cyclic phosphine oxide diacid

A new phosphorylated epoxyimide polymer synthesized was obtained using diimide-diepoxide (DIDE) resin cured with the new curing agent, 10-phenylphenoxa-phosphine-3,8-dicarboxylic acid-10-oxide (PCAO). In addition, compositions of the synthesized diimide-diepoxide (DIDE), Epon 828, with common curing agents, e.g., 4,4′-diaminodiphenylether (DDE) and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity and heat, and flame retardation with that of (PCAO). The reactivities of those curing agents toward the two kinds of epoxy resins, as measured by differential scanning calorimetry (DSC), were in the following order: DDE> PCAO> DDS. Through evaluation of thermal gravimetric analysis (TGA), the thermal and flame resistances of epoxy polymers were confirmed in this study as capable of being significantly improved through introduction of imide and cyclic phosphine oxide group into the epoxide and curing agent structures. © 1996 John Wiley & Sons, Inc.     

Synthesis and properties of polyimides derived from diamine monomer containing bi-benzimidazole unit

A new aromatic heterocyclic diamine monomer containing bi-benzimidazole unit, 2,2-bis(4′-aminophenyl)-5,5-bi-1H-benzimidazole, was synthesized from 2,2-bis(4′-nitrophenyl)-5,5-bi-1H-benzimidazole (BNPBBI) prepared via the reaction of 3,3′,4,4′-biphenyltetramine and p-nitrobenzaldehyde with a high yield. Their compositions and chemical structures containing polybenzimidazole backbone were characterized by FTIR, ¹H NMR and elemental analysis. A series of aromatic polyimides containing the heterocyclic moiety in the main chain were prepared by the reaction of BAPBBI with various aromatic dianhydrides of 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride or pyromellitic dianhydride. The polymers possess a high glass transition temperature of >415 °C and a good thermal stability up to 566 °C with a 5 % weight loss. The combination of polybenzimidazole and polyimide via introducing BAPBBI into the main chains provides the rigid structure, and macromolecular interactions are thus enhanced, resulting in the outstanding mechanical properties. These polyimides exhibit the strong tensile strength of 201 to 327 MPa, and the ultrahigh tensile moduli of 10.7 to 15.5 GPa without post stretching.     

Synthesis of Ester Based Cationic Pyridinium Gemini Surfactants and Appraisal of Their Surface Active Properties

New pyridinium gemini surfactants have been synthesized by esterification of halogenated carboxylic acids with long chain fatty alcohols furnishing respective esters (dodecyl-2-chloroacetate, tetradecyl-2-chloroacetate, hexadecyl-2-chloroacetate, dodecyl-2-bromoacetate, tetradecyl-2-bromoacetate and hexadecyl-2-bromoacetate) followed by their subsequent treatment with 4,4′-trimethylene dipyridine resulting in the formation of title Gemini surfactants: 4,4′-(propane-1,3-diyl)bis1-{2-(dodecyloxy)-2-oxoethyl}; 4,4′-(propane-1,3-diyl)bis{1-(2-(tetradecyloxy)-2-oxoethyl}; 4,4′-(propane-1,3-diyl)bis{1-(2-(hexadecyloxy)-2-oxoethyl} dipyridinium chlorides; 4,4′-(propane-1,3-diyl)bis{1-(2-(dodecyloxy)-2-oxoethyl}; 4,4′-(propane-1,3-diyl)bis{1-(2-(tetradecyloxy)-2-oxoethyl} and 4,4′-(propane-1,3-diyl)bis{1-(2-(hexadecyloxy)-2-oxoethyl} dipyridinium bromides. Their identifications are based on IR, ¹H-NMR, ¹³C-NMR, DEPT, COSY and Mass spectral studies. Their surface active properties were also evaluated on the basis of surface tension and conductivity measurements.     

含苯炔基侧链的聚酰亚胺树脂及其复合材料

采用联苯酐(3,4′-BPDA)与4,4′-二氨基二苯醚(4,4-ODA),3,5-二氨基-4′-苯炔基二苯甲酮(DPEB),苯炔基苯酐(PEPA)制备了不同分子质量的聚酰亚胺树脂。通过流变分析,热重分析,红外光谱,动态热力学分析及静态力学性能测试等研究了分子结构,分子质量等因素对聚酰亚胺树脂耐热性和力学性能的影响。结果表明,合成的聚酰亚胺树脂具有优异耐热性能和较高的韧性,固化后树脂的玻璃化转变温度为379℃,5%热失重温度高于550℃,并且浇注体的拉伸强度是61 MPa,断裂伸长率是6.2%.碳纤维复合材料的室温弯曲强度为1 850 MPa,层间剪切强度为84 MPa,316℃时弯曲强度为946 MPa,剪切强度为46 MPa,具有良好的高温力学保持率。     

Polyimide–polydimethylsiloxane copolymers for low‐dielectric‐constant and moisture‐resistance applications

Novel, randomly coupled, soluble, segmented polyimide–polydimethylsiloxane (PI–PDMS) copolymers were prepared from aminoalkyl‐terminated polydimethylsiloxane (At–PDMS), 4,4′‐oxydianiline diamine, pyromellitic dianhydride, and 4,4′‐diphenylmethane diisocyanate (MDI). When At–PDMS was introduced into the polyimide chain, the polyimide copolymers exhibited lower dielectric constants and better moisture resistance and mechanical properties. The reductions in the dielectric constant of the PI–PDMS copolymers could be attributed to the incorporation of polydimethylsiloxane (PDMS) into the polyimide chain and the nanopores in the film generated by carbon dioxide evolvement during the reaction. The lowest dielectric constant was 2.58 with 25 wt % PDMS and 5 wt % MDI. In addition, the water contact angles of the resultant copolymers increased from 51 to 109° when the contents of PDMS increased from 0 to 25 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009