基于酚酞结构高可溶性聚酰亚胺的合成与性能

以百里香酚酞、对氟硝基苯为起始原料,通过芳香亲核取代和氧化还原反应得到新型芳香二胺单体5,5’-二异丙基-4,4’-二氨基苯氧基-2,2’-二甲基酚酞。该二胺单体分别与3,3’,4,4’-二苯醚四甲酸二酐、3,3’,4,4’-二苯酮四羧酸二酐和3,3’,4,4’-联苯四甲酸二酐以一步法高温缩聚制得了一系列同时含酚酞Cardo结构及异丙基和甲基侧基的高可溶性聚酰亚胺(PI-1、PI-2和PI-3)。该系列聚酰亚胺具有优异的溶解性,室温下不仅可溶于高沸点溶剂N-甲基吡咯烷酮、N,N-二甲基乙酰胺、N,N-二甲基甲酰胺、二甲基亚砜,而且能溶于低沸点溶剂氯仿,二氯甲烷和四氢呋喃,可通过其溶液浇铸制得一系列高性能聚酰亚胺薄膜。所制聚酰亚胺薄膜具有较高的光学透明性,截断波长在324～365 nm之间,450 nm的透过率在56%～78%之间。该系列薄膜玻璃化转变温度在266～289℃之间,在N₂和O₂下10%热失重温度均≥432℃。其拉伸强度在77～95 MPa之间,断裂伸长率在9.1%～13.0%之间,1 MHz下介电常数为2.79～3.01 F/m,...     

可溶性BAPP-MDA-ODPA共聚聚酰亚胺的合成与性能

用2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)和4,4′-二氨基二苯甲烷(MDA)作为二胺,3,3,′4,4′-二苯醚四羧酸二酐(ODPA)作为二酐,以N,N-二甲基甲酰胺(DMF)为溶剂,通过常规的两步法,分别经热亚胺化和化学亚胺化过程合成了可溶性共聚聚酰亚胺。用FT-IR对聚合物的结构进行了表征,FT-IR测试结果表明在1 780 cm-1、1 720 cm-1和725 cm-1左右出现了聚酰亚胺的特征吸收峰。采用溶解性测试、DSC、TGA、拉伸测试和吸水率测试对产物的性能进行了测试。共聚聚酰亚胺在常见有机溶剂中可溶,并且有很好的热稳定性,在氮气氛中,起始降解温度超过500℃,800℃质量保持率为58.2%。共聚聚酰亚胺膜的拉伸强度、拉伸模量、断裂伸长率分别为103.5 MPa,2.36 GPa和11.7%。同时共聚聚酰亚胺膜还有很低的吸水率,为0.87%。     

可溶性PBAP-ODPA-BPADA共聚聚酰亚胺的合成与性能

用4-苯基-2,6-双(4-氨基苯基)吡啶作为二胺,3,3′,4,4′-二苯醚四羧酸二酐和双酚A型二酐作为二酐,以N,N-二甲基甲酰胺(DMF)为溶剂,通过常规的两步法,分别经热亚胺化和化学亚胺化过程合成了3种聚酰亚胺。用傅里叶变换红外光谱对聚合物的结构进行表征,表明在1 780,1 720,725cm-1附近出现了聚酰亚胺的特征吸收峰。采用溶解性测试、X射线衍射、热重分析、拉伸测试和吸水率测试表征了产物性能。所合成的共聚聚酰亚胺溶解性较好,溶于常见有机溶剂。所合成的聚酰亚胺膜热稳定性良好,在氮气氛中,起始降解温度超过500℃,10%失重温度为547.1～601.5℃,800℃质量保持率为64.8%～67.2%。聚酰亚胺膜的拉伸强度、拉伸模量、断裂伸长率分别为105.8～112.6 MPa,2.24～2.32 GPa,9.5%～10.2%。膜的吸水率为0.96%～0.98%。     

DABA-BAPP-BPADA共聚聚酰亚胺的合成与性能

用2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)及3,5-二氨基苯甲酸(DABA)作为二胺,2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐(BPADA)作为二酐,以N,N-二甲基甲酰胺(DMF)为溶剂,通过常规的两步法,分别经热亚胺化和化学亚胺化过程合成了可溶性共聚聚酰亚胺。用FT-IR对聚合物的结构进行了表征,性能测试采用了溶解性测试、DSC、TGA、拉伸测试和吸水率测试。FT-IR图谱表明,在1 780cm~(-1)、1720 cm~(-1)和740 cm~(-1)左右出现了聚酰亚胺的特征吸收峰。共聚聚酰亚胺在常见有机溶剂中可溶,并且有很好的热稳定性,玻璃化转变温度T_g为226.5℃,在氮气氛中降解起始温度508.5℃,800℃质量保持率为46.5%。共聚聚酰亚胺膜的拉伸强度、拉伸模量、断裂伸长率分别为109.7MPa、2.25GPa和15.2%。     

超低介电常数氟化聚酰亚胺合成与性能

分别以4,4′-联苯醚二酐(ODPA)和4,4′-(4,4′-异丙基二苯氧基)二酞酸酐(BPADA)为酸酐单体、2,2-双[4-(4-氨基苯氧基苯)]六氟丙烷(HFBAPP)为胺类单体,采用两步法制备了两种聚酰亚胺(PI)薄膜(PI-1和PI-2).采用傅里叶变换红外光谱仪对薄膜的结构进行了表征,采用差示扫描量热仪和热...     

一类含甲基结构高透明聚酰亚胺的合成与性能

以2,6-二氨基甲苯、3,3′,4,4′-联苯四甲酸二酐、3,3′,4,4′-二苯醚四甲酸二酐为原料,间甲酚作为溶剂,经一步法高温共缩聚,制备一系列可溶性共聚型聚酰亚胺(MPI)。利用FTIR、1HNMR、DSC、TGA和UV等对MPI进行了结构确认与性能表征。结果表明:该系列MPI可溶于N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)、二甲基亚砜(DMSO)等有机溶剂,具有良好的溶解性和成膜性,并随着联苯酐含量的增加溶解性降低;同时,该系列MPI制得的薄膜具有良好的光学透过性能,在紫外光波长450nm时的透过率均在74%以上,截止波长在350 nm左右;该系列MPI的起始分解温度均超过457℃,800℃氮气氛围中的焦炭产率在63%以上,玻璃化转变温度在260～285℃之间,表现出优异的热学性能。此外,该系列MPI薄膜还具有良好的机械性能,其弹性模量在1.7～2.1 GPa之间,拉伸强度在89.7～120.6 MPa之间,断裂伸长率在19.7%～28.4%之间。     

Cardo基低介电聚酰亚胺的合成及性能

以9,9-双(4氨基苯基)芴、对苯二胺、3,3′,4,4′-联苯四羧酸二酐为原料成功制备了一系列含联苯芴(Cardo)基的低介电聚酰亚胺,并表征了其各项性能。通过红外吸收光谱证明了聚酰亚胺的亚胺化程度,X射线衍射(XRD)表征了材料的聚集态结构,材料的分子间距随着Cardo基引入而变大;通过热重分析(TG)和动态热机械分析(DMA)表征了材料的热性能,结果表明,随着分子链中Cardo基含量的增加,玻璃化转变温度从340℃增加到372℃,1%的失重温度从568℃降低到507℃;通过分子模拟表明,大侧基效应导致自由体积增大,分子自由度减弱。介电测试表明,在1 MHz条件下,随着Cardo基含量的增加,介电常数从3.56降低到3.37,介电损耗从0.019降低到0.015。力学性能测试表明,Cardo基引入,材料变脆,拉伸模量和断裂伸长率下降较明显。     

一类含甲基结构高透明聚酰亚胺的合成与性能研究

以2,6-二氨基甲苯、3,3'',4,4''-联苯四甲酸二酐、3,3'',4,4''-二苯醚四甲酸二酐为原料，间甲酚作为溶剂，经一步法高温共缩聚，制备一系列可溶性共聚型聚酰亚胺(MPI)。利用红外光谱（FTIR）、核磁共振波谱（1H NMR）、差式扫描量热仪（DSC）、热重分析仪（TGA）和紫外-可见光分度计（UV）等测试仪器对MPI进行结构与性能表征。结果表明：红外与核磁的数据说明成功合成了含甲基结构的聚酰亚胺；该系列的含甲基聚酰亚胺在室温下可溶于N-甲基吡咯烷酮（NMP）、N,N-二甲基乙酰胺（DMAc）、二氯甲烷（CH2Cl2）三氯甲烷（CHCl3）、二甲基亚砜（DMSO）等有机溶剂，具有良好的溶解性和成膜性，并随着联苯酐的含量增加溶解性降低；同时该系列MPI制得的薄膜具有良好的光学透过性能，在紫外光波长450 nm时的透过率均在74%以上，截止波长在350 nm左右；该系列MPI的起始分解温度均大于457 ℃，800 ℃氮气氛围中的焦炭产率均大于63%，玻璃化转变温度在260 ℃~285 ℃之间，表现出优异的热学性能。此外，MPI-1~MPI-4薄膜还具有良好的机械性能，其弹性模量在1.7~2.1 GPa，拉伸强度在89.7~120.6 MPa，断裂伸长率在19.7%~28.4%。     

BAPP-PBAP-ODPA共聚聚酰亚胺的合成

用2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)和4-苯基-2,6-双(4-氨基苯基)吡啶(PBAP)作为二胺,3,3′,4,4′-二苯醚四羧酸二酐(ODPA)作为二酐,以N,N-二甲基甲酰胺(DMF)为溶剂,通过常规的两步法,分别经热亚胺化和化学亚胺化合成了3种聚酰亚胺。用傅里叶变换红外光谱和核磁共振氢谱表征聚合物的结构,结果表明在1 780,1 720,725 cm~(-1)附近出现了聚酰亚胺的特征吸收峰。采用热重分析,溶解性、拉伸性能和吸水率测试表征了产物性能。所合成的聚酰亚胺溶解性和热稳定性良好,在N_2气氛中,起始降解温度超过500℃;800℃质量保持率为46.2%～64.5%(化学亚胺化)和52.6%～64.8%(热亚胺化)。聚酰亚胺膜的拉伸强度、拉伸断裂应变、拉伸模量分别为107.2～109.6 MPa,7.8%～10.5%,2.13～2.28 GPa。膜的吸水率为0.68%～0.75%。     

可溶性含氟聚芳醚酰胺的合成与性能研究

以自制的高纯二胺单体1,4-双(4.氨基-2-三氟甲基苯氧基)苯与3种商品化二酸单体经缩聚反应制得了一系列新型含氟聚芳醚酰胺(PEA).该含氟PEA表现出优良的溶解性能,室温下不仅可以溶于N-甲基-2-吡咯烷酮、N,N-二甲基乙酰胺、N,N-二甲基甲酰胺等强极性溶荆中,而且还可以溶于吡啶、四氢呋喃、环己酮等低沸点溶剂中.由该聚合物所制得的薄膜无色透明,截断波长在334～364nm之间,加400nm后具有高度透明性.该舍氟PEA还表现出良好的介电性能,介电常数为2.43-2.93(1 MHz).     

Synthesis and nonlinear optical properties of soluble fluorinated polyimides containing hetarylazo chromophores with large hyperpolarizability

The novel fluorinated polyimides with side-chain nonlinear optical (NLO) chromophores were synthesized from hydroxyl polyimides, followed by the Mitsunobu reaction with NLO chromophores. Molecular structural characterization for the resulting polymers was achieved by ¹H NMR, FT-IR, UV-Vis spectra, elemental analysis and gel permeation chromatography (GPC). The polymers exhibit excellent solubility in common organic solvents, good film-forming properties, high glass transition temperature (T_g) in the range from 193 to 200 °C and thermal stability up to 290 °C. The polyimides P1 and P2 containing hetarylazo chromophores with large hyperpolarizability possess a high electro-optic (EO) coefficient (r₃₃), which is larger than that of the polyimide P3 attached DR1. Excellent temporal stability and low optical losses in the range of 1.9-2.1 dB/cm at 1.55 μm were observed for these polymers. Such new NLO fluorinated polyimides are distinguished by an excellent combination of NLO activity, temporal stability, and optical loss.     

Synthesis and properties of a series of cyanate resins based on phenolphthalein and its derivatives

Two new cyanate monomers simultaneously containing phthalide group and different alkyl substituents on the phenylene rings (o-PCY and t-PCY) and the Phenolphthalein-based cyanate (p-PCY) were successfully synthesized by the reaction of o-cresolphthalein, thymolphthalein and phenolphthalein with cyanogen bromide in the presence of triethylamine, respectively. Their chemical structures were confirmed by means of FTIR, NMR and elemental analysis methods. All these monomers owned sufficiently wide processing temperature windows and could be readily cured without the addition of catalyst. The dynamic mechanical analysis (DMA) results showed that the introduction of phthalide structure into the polycyanurate network could effectively improve the thermal properties of the cyanate ester (CE) resin. Especially, the T_g values of the fully cured p-PCY, o-PCY and t-PCY resins are 362 °C, 328 °C and 298 °C, respectively, which are apparently higher than that of most bisphenol-based cyanate resins reported in the literatures (190-290 °C). The thermal and thermo-oxidative properties as well as the water absorptions of the cured products were compared with those of the bisphenol A cyanate resin (BACY), and the structure-property relationships were explained according to the chemical structures and crosslinking densities of the formed polymer networks. The high-T_g thermosetting materials thus prepared are expected to expand the usage of CEs to areas where higher temperature requirements are encountered.     

Synthesis and characterization of polyimides from novel 1-(3′,5′-bis(trifluoromethyl)benzene) pyromelliticdianhydride (6FPPMDA)

Mono-substituted dianhydride monomer, 1-(3′,5′-bis(trifluoromethyl)phenyl) pyromellitic dianhydride (6FPPMDA), was prepared via the Suzuki cross coupling reaction followed by oxidation and cyclodehydration. The monomer was characterized by FT-IR, NMR, elemental analyzer (EA) and melting point apparatus. For comparison, 1-(4′-trifluoromethylphenyl)pyromellitic dianhydride (3FPPMDA) and 1-phenyl pyromellitic dianhydride (PPMDA) were also utilized. The dianhydrides were used to prepare polyimides with aromatic diamines such as bis(3-aminophenyl) 3,4-bis(trifluoromethyl)phenyl phosphine oxide (mDA6FPPO), bis(3-aminophenyl) 4-(trifluoromethyl)phenyl phosphine oxide (mDA3FPPO), bis(3-aminophenyl) phenyl phosphine oxide (mDAPPO) and 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane (p3FDAm). The polyimides were synthesized via a two-step process; preparation of poly(amic-acid) in p-chlorophenol with isoquinoline, followed by solution imidization at the reflux temperature for 12 h. Polymer characterization was carried out by FT-IR, NMR, GPC, DSC and TGA, and their solubility, solution viscosity, water absorption, CTE, dielectric constant and refractive index were also evaluated.     

Synthesis of highly soluble and transparent polyimides

A novel aromatic diamine, 3,3′‐diisopropyl‐4,4′‐diaminophenyl‐4″‐methyltoluene with a 4‐methylphenyl pendant group and isopropyl side groups, was designed and synthesized in this study. Then it was polymerized with various aromatic dianhydrides including pyromellitic dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride via a one‐pot high temperature polycondensation procedure to produce a series of aromatic polyimides. These polyimides exhibited excellent solubility even in common organic solvents, such as chloroform and tetrahydrofuran. The flexible and tough films can be conveniently obtained by solution casting. The films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range 302–365 nm and the wavelength of 80% transparency in the range 385–461 nm. Moreover, they showed low dielectric constants (2.73–3.23 at 1 MHz) and low moisture absorption (0.13%–0.46%). Furthermore, they also possessed good thermal and thermo‐oxidative stability with 10% weight loss temperatures (T_10%) in the range 489–507 °C in a nitrogen atmosphere. The glass transition temperatures of all polyimides are in the range 262–308 °C. Copyright © 2012 Society of Chemical Industry     

Synthesis and properties of aromatic polyimides based on ether-sulfone-diamines

Two diamine monomers, 4,4′-[sulfonylbis(1,4-phenyleneoxy)]dianiline (III _a ) and 4,4′-[sulfonylbis(2,6-dimethyl-l,4-phenyleneoxy)]dianiline (III _b ), were prepared by an aromatic nucleophilic substitution of 4,4′-sulfonyldiphenol (I _a ) and 4,4′-sulfonylbis(2,6-dimethylphenol) (I _b ) with p-chloronitrobenzene in the presence of potassium carbonate, followed by hydrazine catalytic reduction of the intermediate dinitro compounds. The diamines III _a and III _b were used as monomers with various aromatic tetracarboxylic dianhydrides (IV _a–f ) to synthesize polyimides. The polymerization was conducted in two steps via the formation of a poly(amic acid) precursor followed by thermal cyclodehydration. The poly(amic acid)s had inherent viscosities above 0.87 and up to 2.56 dL/g. Most poly(amic acid)s could be coated and thermodehydrated into flexible and transparent polyimide films. The polyimides derived from the dianhydrides containing-O-and-SO₂-or-C(CF₃)₂-bridging groups between the phthalic anhydride units were soluble in some organic solvents such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF). The glass transition temperatures (T_g) of the polyimides were in the range from 254 to 300 °C. The methyl-substituted polyimides exhibited slightly higher solubility and higher T_g compared to the corresponding unsubstituted polyimides. Thermogravimetric analysis (TG) showed that the polyimides containing methyl substitutents started to lose weight around 450 °C and the unsubstituted ones started to lose weight around 550 °C.     

Soluble polyimides from unsymmetrical diamine containing benzimidazole ring and trifluoromethyl pendent group

New unsymmetrical diamine monomer containing both the benzimidazole ring and trifluoromethyl group, 6,4′-diamino-2′-trifluoromethyl-2-phenylbenzimidazole, was prepared from 2-bromo-5-nitrobenzotrifluoride and 4-nitro-1,2-phenylenediamine. The monomer was polymerized with ODPA, BTDA and 6FDA by using one-pot synthetic method to obtain corresponding polyimides. All the prepared polyimides were soluble in aprotic polar solvents. Incorporation of trifluoromethyl groups unsymmetrically in the rigid polyimides improves their solubility without decreasing their physical properties. The polymers showed high glass transition temperature (T_g = 289-352 °C), high thermal stability (T_d10 > 500 °C), and relatively low coefficient of thermal expansion (CTE = 26.1-46.4 ppm/°C) because of their rigid-rod like structure. Also, they showed low refractive indexes (n = 1.46-1.68) and low birefringence (Δ ≈ 0.02) due to the trifluoromethyl pendent groups that interrupt chain packing and increase free volume.     

Synthesis and properties of soluble polyimides based on isomeric ditrifluoromethyl substituted 1,4-bis(4-aminophenoxy)benzene

A new fluorinated diamine monomer, [1,4-bis(4-amino-3-trifluoromethylphenoxy)benzene (2)], and a known isomeric analog 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (3) were synthesized. A series of organosoluble polyimides Ia–d and IIa were prepared from the diamines (2, 3) and dianhydrides (a–d) by a high-temperature one-step method. The effects of the trifluoromethyl substituents on the properties of polyimides were evaluated through the study of their soluble, thermal, optical, and gas permeability properties. Polyimides (Ia–d) had glass transition temperatures between 229 and 279 °C, and the temperatures at 5% weight loss ranged from 510 to 533 °C under nitrogen. These polyimides could be cast into flexible and tough membranes from DMAc solutions. The membranes had tensile strengths in the range of 137–169 MPa, tensile modulus in the range of 1.6–2.2 GPa and elongations at break from 11% to 14%. The polyimide Ia with trifluoromethyl groups ortho to the imide nitrogen exhibited enhanced gas permeability, solubility, transparency, and thermal stability compared with the isomeric polyimide IIa with the CF₃ group meta to the imide nitrogen. Thus, the effect of substituents in the ortho-positions of nitrogen on properties was greater than the effect of substituents in the meta-positions.     

Synthesis and electrochromic properties of aromatic polyimides bearing pendent triphenylamine units

A series of aromatic polyimides with pendent triphenylamine group were synthesized from equimolar mixtures of 4,4′-oxydianiline (ODA) and 4-(3,5-diaminobenzamido)triphenylamine (4), 4-(3,5-diaminobenzamido)-4′,4″-di-tert-butyltriphenylamine (t-Bu-4) or 4-(3,5-diaminobenzamido)-4′,4″-dimethoxytriphenylamine (MeO-4) with two aromatic tetracarboxylic dianhydrides (DSDA or 6FDA) via a conventional two-step procedure that included a ring-opening polyaddition to give poly(amic acid)s, followed by chemical imidization. These polyimides exhibited good solubility in polar organic solvents and could be solution-cast into flexible and strong films. They showed excellent thermal stability, with T_g values in the range of 284–309 °C. The polyimides derived from diamines t-Bu-4 and MeO-4 exhibited reversible electrochemical oxidation, accompanied by strong color changes with high contrast ratio and electrochromic stability. For the polyimides derived from diamine 4, the coupling reaction between the triphenylamine radical cations occurred during the oxidative process forming a tetraphenylbenzidine structure, which resulted in an additional oxidation state and color change together with enhanced near-IR absorption at fully oxidized state.     

Synthesis and characterization of polyimides with low dielectric constants from aromatic dianhydrides and aromatic diamine containing phenylene ether unit

New aromatic polyimides (PIs) having the lowest dielectric constant in nonfluorinated PIs have been developed from aromatic dianhydrides and an aromatic diamine containing phenylene ether units. The diamine monomer was prepared from 4-bromophenyl ether in five steps. Polycondensations were performed in 1-methyl-2-pyrrolidinone at room temperature for 18 h, giving poly(amic acid)s (PAAs) with inherent viscosities up to 0.53 dl/g. PAAs were converted to corresponding poly(imide)s (PIs) by thermal treatment at 300 °C. New PIs showed good thermal stability (5% weight loss around 450 °C) and the low dielectric constant (2.74).