Trimellitic Anhydride Chloride Research Articles

Study on the tribological properties of Si3N4/polyamide-imide composites

Si3N4 whiskers were modified with triethoxysilane as a means to improve the interfacial interaction with a poly-amide imide (PAI). The Si3N4/PAI composites were prepared by in-situ polymerization as an approach to improve the friction behavior and mechanical properties in order to meet the performance needs of electrical transformers and motors in harsh environments. 4,4′-diamino diphenyl ether, m-phenylenediamine, triethylamine, trimellitic anhydride chloride, and Si3N4 whiskers were used to manufacture Si3N4/PAI composite, which was then characterized for friction and mechanical behavior. The research showed that the addition of Si3N4 whiskers improved the mechanical properties and friction properties of PAI. When the whisker content was 10 wt%, the tensile strength of the composite was 137.5 MPa, which is 15% higher than pure PAI, and the wear rate was 0.69 × 10-8 g/N·m, which is 57% lower than pure PAI, and the friction coefficient was 0.47, which was an increase of 9%. In aerospace, machinery, and transportation applications, these materials may have better performance due to their improved combination of properties.

Flexible thin films based on poly(ester imide) materials for optoelectronic applications

AbstractA series of high‐performance poly(ester imide)s bearing cycloaliphatic moieties was manufactured by a two‐step procedure via solution polycondensation of an aromatic–aliphatic dianhydride containing preformed ester units and cyclohexanone ring in the main chain, with various aromatic diamines. The new dianhydride monomer, namely 2‐oxocyclohexane‐1,3‐bis[4,4′‐bis(trimellitate)benzylidene] dianhydride, was synthesized by the reaction between 2,6‐bis(4‐hydroxybenzylidene)cyclohexanone and trimellitic anhydride chloride. The chemical structure of the resulting dianhydride was confirmed by means of Fourier transform infrared, 1H NMR and 13C NMR spectroscopies. The poly(ester imide)s from the series exhibited water uptake capacity in the range 3.45–10.09%. The onset temperatures, corresponding to the first detected thermal weight loss in the samples, ranged from 367 to 441 °C. Besides the cycloaliphatic moieties coming from the dianhydride monomer, the other aliphatic segments present in the diamine structures were responsible for improved optical performance in the resulting poly(ester imide)s, the transmittance being higher than 80% at 684 nm. © 2021 Society of Industrial Chemistry.

From reverse osmosis to nanofiltration: Precise control of the pore size and charge of polyamide membranes via interfacial polymerization

Membranes with suitable nanopores and tunable charge characteristics are highly desired for their good application prospects in specific membrane-based separations. This study focused on the synthesis of polyamide (PA) composite membranes with tunable pore size and perm-selectivity. Trimellitic anhydride chloride (TAC) with an anhydride group, was introduced as the co-reactant of trimesoyl chloride (TMC) to form PA film via interfacial polymerization with m-phenylenediamine on the surface of the polysulfone substrate membrane. Due to the chemistry character difference (the number of functional group and acylation activity) between TMC and TAC, the structure and physico-chemistry properties of the PA film could be tailored through the control of TAC concentration. As a result, the nanopore radius of the membrane varied from <0.32 to 1.14 nm, along with the improved water permeability from 2.3 to 9.8 L m−2 h−1 bar−1 and selectivity of Na2SO4/NaCl from 2.2 to 4.9. This study provided a facile and effective approach for the fabrication of tailor-made membrane with tunable nanopore and ion selectivity designed at a molecular level.

Fabrication of a highly permeable composite nanofiltration membrane via interfacial polymerization by adding a novel acyl chloride monomer with an anhydride group

In this study, a novel acyl chloride monomer trimellitic anhydride chloride (TAC) with an anhydride group was blended with trimesoyl chloride (TMC) as organic phase monomers to fabricate high-flux nanofiltration membranes. Due to the reaction activity differences of organic phase monomers (TMC and TAC) with piperazine, the chemical compositions and structures of polyamide active layer could be tailored through varying the TAC content. It was found that the participation of TAC could yield a looser polyamide separation layer on the polysulfone support membrane, along with an increased surface roughness, hydrophilicity, pore size and negative charge density. As a result, the resultant membrane exhibited excellent water-salt separation. When the TAC concentration was increased to 0.04 wt%, the optimized membrane exhibited a high pure water permeability (PWP) of 13.2 L m−2 h−1 bar−1, up to 2-fold, in comparison with the pristine membrane, whereas the salt rejections of Na2SO4, MgSO4 and NaCl were 97.6%, 92.7%, and 34.0%, respectively. This work provided a novel and facile strategy to develop high-flux NF membrane.

Optically transparent aromatic poly(ester imide)s with low coefficients of thermal expansion. 2: Effect of the introduction of alkyl‐substituted p‐biphenylene units

AbstractA series of ester‐linked tetracarboxylic dianhydrides (TA‐X) were synthesized from trimellitic anhydride chloride and 4,4′‐biphenol analogs containing different numbers and positions of methyl substituents. Aromatic poly(ester imide)s (PEsIs) were polymerized from TA‐Xs and 2,2′‐bis(trifluoromethyl)benzidine to investigate the film properties systematically. A significant substituent effect on the target properties (Tg, optical transparency, the linear coefficient of thermal expansion (CTE) and ductility) was observed. A PEsI containing 2,2′,3,3′,5,5′‐hexamethyl‐substituted p‐biphenylene units was chemically imidized in a homogeneous state. It was highly soluble at room temperature, even in less hygroscopic non‐amide solvents such as cyclopentanone (CPN), and provided a stable CPN solution with a high solid content. The CPN‐cast PEsI film was almost colorless as suggested from the rather low yellowness index (3.2), high light transmittance at 400 nm (71.5%) and very low haze (1.15%). This PEsI film also had a high Tg (294 °C, determined by thermomechanical analysis) in addition to a low CTE (21.7 ppm K−1), moderate film ductility and very low water uptake. A structural modification of the PEsI by copolymerization with a tetracarboxylic dianhydride with a rigid/linear structure was effective in further reducing the CTE while maintaining the other excellent target properties. Thus, some of the PEsIs developed in this work are promising candidates as novel plastic substrates for use in image display devices. © 2017 Society of Chemical Industry

Nature and kinetics of redox imbalance triggered by respiratory and skin chemical sensitizers on the human monocytic cell line THP-1

Low molecular weight reactive chemicals causing skin and respiratory allergies are known to activate dendritic cells (DC), an event considered to be a key step in both pathologies. Although generation of reactive oxygen species (ROS) is considered a major danger signal responsible for DC maturation, the mechanisms leading to cellular redox imbalance remain poorly understood. Therefore, the aim of this study was to unveil the origin and kinetics of redox imbalance elicited by 1-fluoro-2,4-dinitrobenzene (DNFB) and trimellitic anhydride chloride (TMAC), two golden standards of skin and chemical respiratory allergy, respectively. To track this goal, we addressed the time course modifications of ROS production and cellular antioxidant defenses as well as the modulation of MAPKs signaling pathways and transcription of pathophysiological relevant genes in THP-1 cells. Our data shows that the thiol-reactive sensitizer DNFB directly reacts with cytoplasmic glutathione (GSH) causing its rapid and marked depletion which results in a general increase in ROS accumulation. In turn, TMAC, which preferentially reacts with amine groups, induces a delayed GSH depletion as a consequence of increased mitochondrial ROS production. These divergences in ROS production seem to be correlated with the different extension of intracellular signaling pathways activation and, by consequence, with distinct transcription kinetics of genes such as HMOX1, IL8, IL1B and CD86. Ultimately, our observations may help explain the distinct DC phenotype and T-cell polarizing profile triggered by skin and respiratory sensitizers.

Flexible polyimides through one-pot synthesis as water-soluble binders for silicon anodes in lithium ion batteries

A series of polyimides, which contain polyethylene glycol (PEG) segments with different molecular weight in the polymer chains, are synthesized through a facile one-pot method and characterized by Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy. The main part of polyimides is originated from trimellitic anhydride chloride (TMAC) and 4,4′-methylenedianiline, onto which PEG segments are introduced through an esterification reaction with TMAC. These obtained polyimides, which acquire excellent water solubility after being neutralized by triethylamine, are applied as water-soluble binders to silicon negative electrodes for lithium ion batteries, and significantly improve the electrochemical performance of silicon anodes. Specially, the PI-200 (polyimide copolymerized with PEG-200) based silicon electrode exhibits a high initial discharge capacity of 2989.7 mAh g−1 and remains about 2235.5 mAh g−1 after 200 cycles at the current density of 0.1 C (420 mA g−1).

Preparation of solution-processable colorless polyamide-imides with extremely low thermal expansion coefficients through an in-situ silylation method for potential space optical applications

AbstractSeveral tough and flexible fluorinated polyamide-imide films were prepared from trimellitic anhydride chloride and 2,2′-bis(trifluoromethyl)benzidine through a facile one-pot in-situ silylation method. By incorporating fluorinated side groups, the solubility of the prepared polyamide-imide was greatly enhanced. Meanwhile, due to their linear chain configuration and the existence of hydrogen bonding, the prepared polyamide-imide films revealed high tensile strength, high tensile modulus, high glass transition temperature (Tg) and most interestingly, very low coefficient of thermal expansion (CTE) of 11 ppm/°C. Copolymerization with pyromellitic dianhydride (PMDA) led to an extremely low CTE of 4 ppm/°C which should be among the lowest values available for soluble polyamide-imides. The optical homogeneity and stress homogeneity of the obtained polyamide-imide films were also tested. After non-contact with substance and thermal treatment at 300°C, they revealed a better optical homogeneity and stress homogeneity than that of the commercially available Kapton polyimide (PI) films, with a PV value of 0.915 λ and RMS value of 0.163 λ. Thus, these colorless and soluble polyamide-imide films simultaneously possessing promising optical imaging performance are good candidates as novel diffractive membrane optical system architectures.

Poly(amide-imide-esters) derived from asymmetric diacids and diphenols containing silicon or carbon as central atom. Synthesis, characterization and thermal studies

Poly(amide-imide-esters) (PAIEs) were obtained from a series of unsymmetrical diacids containing an amide and an imide group in the structure and diphenols containing Si or C as central atoms. The unsymmetrical diacids were obtained from trimellitic anhydride chloride which reacted with p-aminobenzoic acid, followed by the reaction of the resulting amide–imide acid with an amino acid such as glycine, L-alanine, L-valine, and p-aminobenzoic acid. The obtained monomeric diacids were polymerized with bisphenol-A and with the analogous bisphenol containing silicon as central atom to give PAIEs. These polymers were characterized by spectroscopic methods and their main properties such as solubility, molecular weight, glass transition, and thermal stability were studied in correlation with the presence of C or Si atoms in the bisphenol segment and with the amount of aromatic units in the diacid segment.

Facile synthesis of AIE-active amphiphilic polymers: Self-assembly and biological imaging applications

In this work, we reported a rather facile method for fabrication of ultrabright, well dispersible and biocompatible fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) properties through combination of esterification and ring-opening reaction. The hydroxyl groups of Pluronic F127 was first reacted with the chloride of trimellitic anhydride chloride (TMAC), and its anhydride groups were further reacted with the amino groups of amino-terminated AIE dye (PhNH2) through ring-opening reaction. The optical properties, biocompatibility as well as cell uptake behavior of these obtained AIE-active nanoparticles (F127-TMAC-PhNH2 FONs) were examined by a series of characterization techniques and assays. We demonstrated that uniform organic nanoparticles with high water dispersibility, strong luminescence and desirable biocompatibility can be facilely obtained, which are promising for biological imaging applications. More importantly, a number of carboxyl groups were introduced into these AIE-active nanoparticles, which can be further utilized for further conjugation reaction and carrying anticancer drugs such as cisplatin. Therefore, the strategy of described in this work should be a simple and useful route for fabrication of multifunctional AIE-active luminescent nanotheranostic systems.

Synthesis of highly transparent poly(amide–imide)s based on trimellitic acid and dependence of thermal properties on monomer sequence

Transparent, thermally stable, and semiaromatic poly(amide–imide)s were prepared from hydrogenated trimellitic anhydride chloride (h-TAC) with various aromatic diamines. The dependence of thermostability on the monomer sequence and terminal group was investigated. Thermogravimetric/differential thermal analysis (TG/DTA) was performed to evaluate the thermostabilities, which were found to be primarily affected by the monomer sequence in the polymer units. The 5% weight loss temperature (Td5) in N2, glass transition temperature (Tg), and cutoff wavelength of the ultraviolet–visible (UV–Vis) spectrum (λcut) of the semiaromatic poly(amide–imide)s are 422–456°C, 131–274°C, and 293–321nm, respectively, while those of wholly aromatic poly(amide–imide)s are 454–480°C, 169–287°C, and 415nm, respectively.

Syntheses of biocompatible polyimide and poly(amide-imide) containing phosphorylcholine moiety and the coating ability of the nanosheets

Event Abstract Back to Event Syntheses of biocompatible polyimide and poly(amide-imide) containing phosphorylcholine moiety and the coating ability of the nanosheets Mari Ogino1*, Kohei Asao1*, Haruki Oka1*, Ryo Matsunaga1*, Yosuke Okamura1* and Yu Nagase1* 1 Tokai University, Course of Industrial Chemistry, Graduate School of Engineering, Japan Introduction: It has been well known that poly(2-methacryloyloxyethyl phosphorylcholine), MPC polymer, exhibited the excellent biocompatibility derived from phosphorylcholine (PC) group[1]. In these years, we have succeeded in the syntheses of diamine and diol monomers containing PC group to develop novel biomaterials, which were prepared by polycondensation or polyaddition using these monomers[2],[3]. Especially, it was found that soluble polyimides and poly(amide-imide)s having PC group exhibited the good biocompatibility derived from PC group in addition to the high thermal stability derived from rigid backbone. By the way, we focused on the polymer ultrathin film with a thickness less than 100 nm, so called nanosheet, which possessed interesting features such as flexibility, adhesiveness and smoothness[4],[5]. Therefore, in this paper, we attempted to fabricate the nanosheets from these polymers, and the application to the coating agent consisted of the fragmented nanosheets was investigated. Materials and Methods: A PC-diamine monomer, 2-[3,5-bis(4-aminophenoxy)phenylcarbonyloxy]ethyl phosphorylcholine (BAPPC), was synthesized according to the literature[2]. Next, polyimide (PIPC) and poly(amide-imide) (PAIPC) containing PC group were prepared by the polycondensation of BAPPC and 3,5-bis(4-aminophenoxy)benzene (BAP) with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or trimellitic anhydride chloride (TMAC) followed by the chemical imidization, as shown in Scheme 1. The nanosheets of these polymers were fabricated by spin-coating method, and they were peeled off by “sacrificial layer method” according to the literature[4]. Then, the nanosheets were homogenized in water to obtain fragmented nanosheets of submillimeter-size. Moreover, the coating ability of the dispersion of fragmented nanosheets in water was evaluated. Results and Discussion: The polyimides (PIPC20, 50) and poly(amide-imide)s (PAIPC30, 50) were prepared by changing the molar ratio of BAPPC and BAP in the polymerizations. These polymers were soluble in aprotic polar solvents such as DMF, DMSO and NMP, in which PIPC20 was also soluble in chloroform and THF. It was found by the thermogravimetric analysis that the thermal stability of these polymers was over 200°C, which was expected to be stable for the heating sterilization. Meanwhile, the nanosheets of these PC-polymers were successfully prepared, the thickness of which could be controlled by changing the concentration of polymer solution. Then, it was confirmed from the platelet adhesion test that the obtained nanosheets exhibited the high antithrombogenic property, as shown in Figure 1(B) and (C). Furthermore, several substrates could be coated by the fragmented nanosheets, and the coated surfaces of fragmented nanosheets exhibited the improved antithrombogenicity as shown in Figure 1(D) and (E). Conclusion: In this study, it was revealed that the obtained polyimide and poly(amide-imide) containing PC group showed good features for biomaterials, and the nanosheets of these polymers could be used as coating agents for several substrates. Therefore, it is expected that these nanosheets composed of PC polymers will be applied to coating reagents on the several surfaces of medical devices, for example, catheters, artificial vessels, and microfluide devices.

Inhibition of carbonic anhydrase isoforms I, II, IV, VII and XII with carboxylates and sulfonamides incorporating phthalimide/phthalic anhydride scaffolds

We report a panel of carboxylates and sulfonamides incorporating phthalic anhydride and phthalimide moieties in their structure and their interaction with the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). They were synthesized from substituted anthranilic acids and trimellitic anhydride chloride, followed by reaction with primary amines and were tested for the inhibition of five physiologically relevant CA isoforms, the human (h) hCA I, II, IV, VII and XII, some of which are involved in serious pathologies (CA II, IV and XII in glaucoma; CA VII in epilepsy; CA XII in some solid tumors). The carboxylic acids were generally poor inhibitors of isoforms hCA I, II and IV but were highly effective, low nanomolar inhibitors of hCA VII and XII. The sulfonamides inhibited all isoforms significantly, and some of them were sub-nanomolar hCA VII inhibitors, although their isoform selectivity was lower compared to the carboxylates. This study proves that carboxylic acids incorporating a phthalic anhydride/phthalimide based scaffold may lead to isoform-selective inhibitors by applying the tail approach, mostly used up until now for obtaining sulfonamide, sulfamide and sulfamate CA inhibitors.

Optically transparent aromatic poly(ester imide)s with low coefficients of thermal expansion (1). Self-orientation behavior during solution casting process and substituent effect

A series of ester-linked tetracarboxylic dianhydrides were synthesized from trimellitic anhydride chloride and hydroquinone (HQ) analogs including various alkyl substituents. The properties of aromatic poly(ester imide)s (PEsI) prepared from the tetracarboxylic dianhydrides and 2,2′-bis(trifluoromethyl)benzidine (TFMB) were investigated for applications as novel plastic substrate materials in image display devices. The chemically imidized PEsI from trimethyl-substituted HQ was soluble even in less hygroscopic solvents such as cyclopentanone (CPN). Simple casting from the CPN solution provided a flexible and less colored film with a considerably low coefficient of thermal expansion (CTE = 11.5 ppm K−1), a high Tg of 276 °C, high thermal stability (5% weight loss temperature in N2: 453 °C), and very suppressed water uptake (WA = 0.13%). The low CTE results from highly aligned main chains along the X–Y direction, which occurred during solvent evaporation after the PEsI solution was coated on a substrate. A mechanism is also proposed for such self-orientation behavior in this work. On the other hand, the thermally imidized counterpart was worthless in terms of low CTE and high transparency. Some conventional rigid tetracarboxylic dianhydrides were copolymerized with a minor content to di-tert-butyl- and diamyl-substituted PEsI systems. This approach was very effective not only for further improving some thermal properties (low CTE and high Tg) but also for suppressing film yellowness while keeping excellent solution-processability. Thus, some of the PEsIs developed in this work can be promising candidates as novel plastic substrate materials.

Preparation and characterization of an amphoteric chitosan derivative employing trimellitic anhydride chloride and its potential for colon targeted drug delivery system

Trimellitic anhydride chloride was used to generate a water soluble amphoteric chitosan derivative (CTAA). CTAA was combined with alginate to facilitate direct targeting of 5-FU to the colon. The structure of CTAA was characterized by FTIR, 1H/13C NMR and HSQC. The physical properties of the CTAA hydrogel were analyzed by scanning electron microscopy, X-ray diffraction and thermogravimetry. Inhibition of a pancreatic enzyme's activity and cytotoxicity studies of CTAA were also carried out. Sodium alginate was mixed with CTAA to form a polyelectrolyte complex film and resulted in improved controlled drug release. Swelling characteristics of the films as a function of pH were also investigated. An optimized formulation was exposed to conditions simulating the stomach, small intestine, and colon. The CTAA/alginate formulation used in this preliminary study presents potential for at least 28% of ingested 5-FU to arrive at the colon ready for release by colonic enzymes. Films were chosen in the study to severely stretch the capabilities of the CTAA/alginate system. The system nevertheless will need modifying for in vivo delivery to the colon.

Effect of alternation of polyamide selective layers in the formation and performance of thin-film composite membranes

Polyamide thin-film composite membranes were prepared on a reinforced microporous polyethersulfone (PES) support by in situ interfacial polycondensation of amic acid diamines (AADs) with 1,3,5-benzenetricarbonyl trichloride and subsequent curing. Water soluble AADs were synthesized by reacting trimellitic anhydride chloride and cyclic/aromatic diamines in dimethylformamide at 5–10°C. Polyamide ultra-thin barrier layer containing different structural modifications were isolated by dissolving the matrix PES support in dichloromethane and characterized for IR, NMR, and DSC techniques. Morphology of membranes by scanning electron microscopy showed the appearance of honeycomb-like structure on the polyamide skin surface and the cross section displayed the presence of nodular structure which arises from the dense polyamide skin. The performances of these membranes were measured by passing the feed solutions containing 2,000 ppm of NaCl and Na2SO4 in a reverse osmosis test kit. Membranes exhibited very broad range of separations for NaCl (35–85%) and Na2SO4 (40–89%) depending on the chemical nature of the AADs. The glass transition temperature (Tg) of composite membranes with aromatic diamine structures were >220°C, indicating the higher stiffness nature of the polymer chain due to the presence of fully aromatic structural units.

Aerobic oxidation of cumene catalysed by 4-alkyloxycarbonyl-N-hydroxyphthalimide

Abstract 4-Hexyloxycarbonyl-, 4-dodecyloxycarbonyl- and 4-hexadecyloxycarbonyl-N-hydroxyphthalimides were synthesised using trimellitic anhydride chloride as the starting material. The obtained lipophilic derivatives of N-hydroxyphthalimide were applied as catalysts of the cumene oxidation reaction with oxygen performed in polar acetonitrile, in non-polar tert-butylbenzene and in the absence of a solvent. The courses of reactions catalysed by N-hydroxyphthalimide and its derivatives were compared.

에스터기를 가지는 무수물과 다양한 아민 단량체를 이용한 폴리이미드 필름

Trimellitic anhydride chloride와 hydroquinone을 이용하여 hydroquinone bis(trimellitate anhydride)(HQ-TA)를 합성하였다. 합성된 HQ-TA와 6가지의 다양한 디아민들을 사용하여 전구체 polyamic acid(PAA)를 합성한 후, 열적-및 화학적-이미드화 반응을 거쳐 에스터 그룹을 가지는 폴리이미드(polyimide, PI) 필름을 합성하였다. PI 합성은 구조적으로 다양한 방향족 디아민을 사용하였다. 각 디아민 구조에 따른 유리전이온도(<TEX>$T_g$</TEX>)는 167-<TEX>$215^{\circ}C$</TEX>를 보였고, 초기분해온도(<TEX>${T_D}^i$</TEX>)는 <TEX>$364-451^{\circ}C$</TEX>를 나타내었다. 가장 향상된 열팽창 계수(coefficient of thermal expansion, CTE)와 가스차단성은 TFB(3.23 <TEX>$ppm/^{\circ}C$</TEX>)와 4,4-ODA(< <TEX>$10^{-2}cc/m^2/day$</TEX>) 단량체를 각각 사용하였을 때 보였다. PI 필름의 투과도는 500 nm에서 65-89%를 보였으며, 노란색 정도를 나타내는 황색지수(yellow index, YI)는 3.01-69.52를 보였다. Hydroquinone bis(trimellitic anhydride) (HQ-TA) was synthesized from trimellitic anhydride chloride and hydroquinone. Poly(amic acid)s (PAAs) were synthesized by reacting a HQ-TA with six different diamines, which were cyclized to yield polyimides (PIs) containing ester linkages by chemical- and thermal-imidization methods. The various PIs were synthesized from structurally different aromatic diamines. The glass transition temperatures (<TEX>$T_g$</TEX>) were in the range of 167-<TEX>$215^{\circ}C$</TEX>, and the decomposition temperatures (<TEX>${T_D}^i$</TEX>) were in the range of <TEX>$364-451^{\circ}C$</TEX>. The maximum improvements in coefficient of thermal expansion (CTE) and barrier to oxygen permeation were observed in PIs using TFB (3.23 <TEX>$ppm/^{\circ}C$</TEX>) and 4,4-ODA (< <TEX>$10^{-2}cc/m^2/day$</TEX>), respectively. The PI films possessed a transmittance of 65-89% at 500 nm and had a yellowish color with a yellow index (YI) of 3.01-69.52.

Preparation, characterization and thermal degradation study of poly(amide imide)s based on tri-component mixture of PMDA/BTDA, diamines and acid chloride

A series of poly(amide imide)s (PAIs) having alternate (amide–amide) and (imide–imide) units (polymers 1–14 and 22–35), and random distribution of amide-imide linkages (polymers 15–21 and 36–42) were prepared by low temperature solution polymerization of benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA)/benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (BTDA), diamines (cyclic and aromatic) and acid chloride in dimethylforamide. All the polymers were readily soluble in polar aprotic solvents with inherent viscosities in the range of 0.134–0.878. The process of cycloimidization of poly(amide amic acid)s (PAAs) to PAIs was investigated by TGA and FT-IR techniques at four different temperatures i.e., 175, 200, 225, and 260 °C. The rate of cycloimidization was calculated by taking into account the theoretical weight loss (WT), obtained from [n × Mw (H2O)/Mw (RU)] W, where Mw (H2O) molecular weight of water, W weight of PAA taken for TGA, Mw (RU) the molecular weight of repeat unit of PAA, n number of water molecules eliminated per repeat unit of PAA upon cycloimidization. For a particular diamine, the extent of percentage cycloimidization at the end of the isothermal heating was higher for PAAs containing trimellitic anhydride chloride (TMAc) unit, irrespective of the nature of the dianhydride and diamine. Thermal and thermooxidative degradation of PAIs was investigated by TGA in nitrogen and oxygen atmosphere. The initial decomposition temperatures (IDT) of polymers are above 260 °C, and vary widely (from 260 to 501 °C) depending upon the structure of the polymer backbone. PAIs containing TMAc exhibited higher thermal stability as compared to those polymers having diacid chloride units, in both N2/O2 atmospheres.

Solution-processable transparent polyimides with low coefficients of thermal expansion and self-orientation behavior induced by solution casting

A fluorinated tetracarboxylic dianhydride (amide-type TA-TFMB) was prepared from trimellitic anhydride chloride and 2,2′-bis(trifluoromethyl)benzidine (TFMB). A chemically imidized polyimide (PI) derived from TA-TFMB and TFMB was rather soluble in various solvents. Solution casting of this PI (TA-TFMB/TFMB) led to a flexible, non-turbid, and seemingly almost colorless PI film with a high Tg of 328°C and a considerably low coefficient of thermal expansion (CTE) of 9.9ppmK−1 which results from significant in-plane chain orientation induced during solution casting. The self-orientation mechanism is discussed. The properties of TA-TFMB/TFMB were compared with those of some relevant systems. The results suggest that an electron-withdrawing effect of the 2,2′-CF3 substituents of TA-TFMB and a twisted conformation of the central biphenyl moiety greatly contribute to the suppressed coloration of the TA-TFMB/TFMB film. The use of a TA-TFMB counterpart (ester-type TA-TFBP) was effective for further enhancing the transparency owing to reduced charge-transfer interaction. However, the thermal properties of TA-TFBP/TFMB were not always satisfactory. Copolymerization using 2,3,6,7-naphthalenetetracarboxylic dianhydride led to a PI film with an increased Tg of 277°C and a very low CTE of 12.6ppmK−1 without significant decreases in the transparency and the solubility. Thus, this work proposes promising candidates as novel heat-resistant plastic substrate materials in display devices.