Original Polyimide Research Articles

High-performance triboelectric nanogenerator with aminated barium titanate composite nanoparticles for early Parkinson’s disease diagnosis

High dielectric constant nanoparticles into polymer matrices have attracted much attention because this process can improve the nanofriction generator performance. However, the dispersion of the developed materials remains a challenge. In this paper, we present a novel high-performance nanofriction generator (FBT-TENG) based on composite nanoparticles of Amino-functionalized barium titanate and functionalized graphite oxide (FGO/ABTO) with Polyimide (PI) as substrate, which can be used as a sensor for intelligent monitoring systems. Specifically, we introduced amino groups on the surface of barium titanate to improve its dispersion in the PI solution, and the dual effect composite with functionalized graphite oxide improved the TENG performance of the PI film. Due to the FGO/ABTO synergy, the FBT-TENG can generate high output voltages, currents and power densities of 75 V, 13 µA and 4.6 W/m2, respectively, which is a 9 times increase in power density compared to the original PI film. FBT-TENG is capable of powering capacitors. In addition, the FBT-TENG can be used as a sensor to build an early Parkinson’s disease detection system, which provides a more convenient option for the early diagnosis of Parkinson’s patients and has the potential for a wide range of medical applications.

Reducing moisture ingress in flexible sensors with laser patterned polyimide

Polymeric materials that can more effectively act as barriers to environmental factors such as moisture are of significant interest to the sensor fabrication industry. Moisture ingress may corrode metallic traces or cause the decohesion of bonded interfaces of flexible sensors. Often, imparting a higher degree of moisture resistance necessitates encapsulating the sensors or applying specialty coatings. In this study, a laser patterning process is used to modify standard polyimide coverfilms used in flexible sensor manufacturing. The study achieved patterned polyimide surfaces in the partial wetting Cassie-Baxter regime which displayed reduced moisture diffusivity compared to the original polyimide surface by an order of magnitude. These surfaces displayed periodic structures with deep channels, a high developed interfacial area ratio, and a low contact angle. A laser-patterned sensor that makes use of this coverfilm-enhancing technique is demonstrated. Avoiding the need to apply additional moisture resistant films and instead laser patterning existing coverfilms could provide significant benefits to the flexible sensor industry, simplifying the fabrication of more robust sensors that are less prone to environmental degradation.

Preparation and performance study of ionic liquid @ boron nitride modified polyimide proton exchange membrane

AbstractProton exchange membrane (PEM) plays a relatively significant part in PEM fuel cells (PEMFCs). In this study, ionic liquid were grafted onto boron nitride (ILs@BN) were prepared by wet ball milling, and the polyimide (PI) composite films with different contents (1, 2, 3, 4, and 5 wt%) of ILs@BN were fabricated by solution‐casting method. Results showed that compared with the original polyimide films, the performance of the obtained composite films has been significantly improved. Tensile strength of film containing 4 wt% ILs@BN was enormously enhanced by 93.62% (from 47 to 91.8 MPa), respectively, in contrast to pure PI film. Compared with pure PI film, film containing with 4 wt% ILs@BN was reduced from 71.2° to 63.2°, which indicated the better hydrophilicity of the film and potential proton transport channels. The composite film exhibited excellent proton conductivity, which was tremendously elevated by 58.35% (from 0.1215 S cm−1 for pure PI to 0.1924 S cm−1 for film containing with 4 wt% ILs@BN). Comprehensively, the film containing with 4 wt% ILs@BN presenting excellent mechanical properties (91.8 MPa), contact angle (63.2°) and proton conductivity (0.1924 S cm−1) demonstrating strong potential applications in fuel cells.

Effect of Trap Regulation on Vacuum DC Surface Flashover Characteristics of Nano-ZnO/PI Film.

The operating safety of spacecraft in space environments is closely related to the surface discharging phenomenon of dielectrics such as polyimide (PI) film in solar arrays; moreover, carrier traps in the dielectric can affect its insulation performance. Therefore, to improve the vacuum surface flashover characteristics of PI film by nano modification and reveal the effect of trap distribution on the flashover of PI composite film, first, the original PI and nano-ZnO/PI composite films with different additive amounts (0.5, 1, 2, and 3 wt.%) were prepared by in situ polymerization and their performance was evaluated by the physicochemical properties characterized by methods such as thermogravimetric analysis; second, the surface traps of the original and nanocomposite films were measured and calculated by surface potential decay method, and the carrier mobility was also obtained; finally, the vacuum direct current (DC) surface flashover characteristics and bulk resistivity of all the film samples were measured and analyzed. The experiment results showed that with the increase in the amount of nano-ZnO, both the shallow and deep trap density increased significantly, while the trap energy varied slightly, and the surface flashover voltage also increased obviously. Based on the multi-core model, the increases in the shallow and deep trap density after the introduction of nano-ZnO into the PI matrix was analyzed from the microscopic perspective of the interface. Based on the comparative analysis of the trap distribution and surface flashover voltage characteristics, a bilayer model of vacuum DC surface flashover development was proposed. In the bilayer model, deep traps and shallow traps play a dominant role in the vacuum–solid interface and the inner surface of the dielectric, respectively, and increasing the trap density could effectively inhibit secondary electron multiplication on the surface and accelerate charge dissipation inside the film. Consequently, nano-ZnO can purposefully control the trap distribution, and then improve the flashover characteristics of nano-ZnO/PI composite films, which provides a new approach for improving the spacecraft material safety.

Photoluminescence, thermal and surface properties of triarylimidazole-containing polyimide nanocomposite films.

In this work, a triarylimidazole-containing diamine 2-(4-methylphenyl)-4,5-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)imidazole (MPBAI) was firstly synthesized and polymerized with 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) to prepare transparent polyimide (PI) films by means of thermal imidization. Then, inorganic nanoparticles including silica (SiO2), alumina (Al2O3) and silicon nitride (Si3N4) were separately introduced into the PI(MPBAI-CBDA) with different mass fractions of 0.02%, 0.10%, 0.50% and 2.50% to obtain three series of PI nanocomposite films. All these films were close to colorless and transparent, although the light transmittance showed a downward trend due to the introduction of nanoparticles. Moreover, as the content of inorganic nanoparticles increased, the fluorescence intensities of these films were increased. Comparatively, the improvement effect of nano-SiO2 was the most obvious. When the content of SiO2 was 2.50%, the maximum intensity of the fluorescence absorption peak was increased by 9.6 times, and the absolute fluorescence quantum yield reached 17.2%, about 5.2 times that of the original PI film. Moreover, the maximum absorption peak produced a red shift of 85 nm due to the addition of 2.50% Si3N4, which was probably caused by the weakening of fluorescence quenching effect and high permittivity. The nanocomposites exhibited high glass transition temperatures of around 300 °C and excellent thermal stabilities. The surface hydrophobicity was changed by adjusting the mass and type of nanoparticles. Thus, this work provided a simple way to improve the photoluminescence effect by introducing the nanoparticles. The functional films will be expected to be applied in some optical applications.

Ecofriendly Preparation of Cellulose Nanocrystal-Coated Polyimide Fiber: Strategy for Improved Wettability.

Polyimide (PI) fibers pose potential problems in applications. Their low surface activity causes poor interfacial wettability, easy agglomeration in aqueous solutions, and poor dispersibility. Therefore, this work proposes a method of surface modification of alkali-treated PI fibers with cellulose nanocrystals (CNCs) under the combined catalytic action of a Lewis acid and a crosslinker. The dispersion degree of PI fibers in aqueous solution before and after CNC modification and the contact angle of the PI fiber paper are measured. The results show that the wettability of the PI fibers improved. Furthermore, the structure and properties of PI fibers before and after CNC treatment are characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The pore-size distribution of the PI-fiber paper is measured by a porous-material pore-size analyzer. Compared with the original PI fibers, the oxygen content of the fiber surfaces increases after CNC treatment because of the esterification reaction and crosslinking that occur on the surfaces. The increase in the number of oxygen-containing polar groups and the increased surface roughness of the PI fiber improve its wettability. The contact angle of the PI fiber paper in deionized water is reduced by 14.9° and that in ethanol by 4.8°; the fiber dispersion degree is increased by 45%. These results indicate that the fibers have remarkably improved hydrophilicity and dispersion in the aqueous phase. Therefore, the method developed herein is to prepare high-performance organic fibers and corresponding composite materials.

Fabrication and enhanced dielectric constant of nanocomposite films based on polyimide and core–shell structured Al2O3@0.4mol%Nb-(Ba0.87Sr0.04Ca0.09)(Ti0.86Zr0.08Sn0.06)O3 nanoparticles

A series of nanocomposite films loaded with various concentrations of fillers were successfully synthesized by solution casting method (BSCTZS nanoparticles (NPs) as filler and polyimide (PI) as polymer matrix). To improve the dispersion and the physical–chemical properties of (Ba0.87Sr0.04Ca0.09)(Ti0.86Zr0.08Sn0.06)O3 (BSCTZS) NPs surface, BSCTZS NPs were modified by Al2O3 coating and modified Al2O3@Nb-BSCTZS NPs/PI nanocomposite films were prepared. The prepared modified Al2O3@Nb-BSCTZS NPs were characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of these composites were characterized in details. As a result, the nanocomposite films filled with 5 vol% Al2O3@0.4mol%Nb-BSCTZS nanoparticles exhibit an excellent energy density of 2.11 J cm−3 at 298 kV/mm, which is 48% over the original pristine PI (1.42 J cm−3 at 313 kV/mm). This work can provide a prospective solution for the preparation of composite film materials with high dielectric constant and high energy density.

Effects of water absorption on surface charge and dielectric breakdown of polyimide/Al2O3nanocomposite films

The incorporation of inorganic nano particles (TiO2, Al2O3 and SiO2 etc.) with polyimide (PI) greatly improves its dielectric property. The dielectric properties of PI films are largely influenced by the absorbed water and humidity. What is more, the water absorption will be affected greatly by nano particles. In this paper, to study the effects of absorbed water on dielectric properties of moistened PI/Al2O3 composite film, PI film specimens were prepared by incorporating 12 wt% nano Al2O3 particles with PI. The original specimens were also prepared for contrast. Then the specimens were immersed in high purity water for 12, 24, 48, 72, 96, 120, 144 and 168 h. The water absorption and breakdown strength under different immersion time were measured. Meanwhile, given that the existence of surface charge had a critical influence on the breakdown characteristics, the corona charging tests were conducted at room temperature under pulse voltage. The pulse frequency was 300, 600 and 900 Hz, respectively. The pulse amplitude was +4 kV. The charge dissipation was investigated based on the demarcation energy theory. Obtained results show that the moisture condition affects more on the nano Al2O3 composite films than the original ones. Compared to original PI films, the water absorption is larger and the breakdown strength falls faster for the nano ones. The decay process of surface charge and the change of detrapping charges in nanocomposite films are affected greatly by the absorbed water.

Thin-film composite membranes for organophilic nanofiltration based on photo-cross-linkable polyimide

This work demonstrates that it is possible to prepare new, competitive thin-film composite (TFC) membranes with a polyolefin ultrafiltration membrane as support and with a non-porous photo-cross-linked polyimide as separation layer for organic solvent nanofiltration. The commercial polyimide Lenzing P84® was modified by a polymer-analogous reaction to introduce side groups with carbon–carbon double bonds to increase its photo-reactivity with respect to cross-linking. Polymer characterization revealed that this was successfully achieved at acceptable level of main chain scission. The higher reactivity of the photo-cross-linkable polyimide had been confirmed by comparison with the original polymer; i.e., shorter gelation times upon UV irradiation, higher suppression of swelling by solvents and complete stability in strong solvents for not cross-linked polyimide such as dimethylformamide (DMF) had been obtained. For films from unmodified and modified polyimide, the degree of swelling in various solvents could be adjusted by UV irradiation time. Photo-cross-linking of the original polyimide did not lead to stability in DMF. TFC membranes had been prepared by polymer solution casting on a polyethylene ultrafiltration membrane, UV irradiation of the liquid film and subsequent solvent evaporation. Polyimide barrier film thicknesses between 10 and 1μm were obtained by variation of cast film thickness. Performance in organic solvent nanofiltration was analyzed by using hexane, toluene, isopropanol and DMF as well as two dyes with molar masses of ∼300 and ∼1000g/mol. Permeances of TFC membranes from unmodified polyimide were low (<0.1L/hm2bar) while rejections of up to 100% for the dye with ∼1000g/mol could be achieved. TFC membranes from modified and photo-cross-linked polyimide had adjustable separation performance in DMF with a trade-off between permeance and selectivity, in the same range (e.g.: 0.3L/hm2bar and 97% rejection for the dye with ∼1000g/mol) as a commercial conventional polyimide membrane tested in parallel. The established membrane preparation method is promising because by tuning the degree of cross-linking of the polymeric barrier layer, the membrane separation performance could be tailored within the same manufacturing process.

Synthesis and characterization of thermally stable camphor-based polyimide--clay nanocomposites

A new monomer was prepared from (1R,3S)-(+)-camphoric acid. Novel polyimide and polyimide--clay hybrid composites were developed from one-pot condensation reactions of this monomer and pyromellitic dianhyride. Polyimide-montmorillonite nanocomposites were prepared from solution of polyimide and with different weight percentages (1, 5, 10 wt %) of organo-modified montmorillonite (OM-MMT) using N-methyl-2-pyrrolidone (NMP) as aprotic solvent. The reactive organoclay was formed by using hexadecylpyridinium chloride as a swelling agent for silicate layers of montmorillonite. The polyimide--clay composites films (PI--MMT) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). All composites were subjected to differential scanning calorimetry measurements for the purpose of examining Tg from all compositions. The clay content significantly influenced the thermal behavior of the polymeric films, such as glass transition and decomposition temperatures of polyimide--clay composites. The glass transition temperatures of the composites were higher than that of the original polyimide. Their thermal decomposition temperatures (Td = temperature at 5% mass loss) were measured via thermogravimetric analysis and showed that the introduction of clay into polymer backbones increased thermal stability. SEM, XRD, and the other conventional techniques were used for structural characterization. Dispersion of the modified clay in the polyimide matrix resulted in nanostructured material containing intercalated polymer between the silicate layers. The morphology and properties of PI nanocomposites greatly depend on the functional groups of the organic modifiers, synthesis procedure, and structure of polyimide because of the chemical reactions and physical interactions involved.

Preparation of novel polyimide hybrid materials by multi-layered charge-transfer complex formation

A versatile method for the post-modification of sulfonated polyimides by charge-transfer (CT) complex formation between electron-deficient naphthalenediimide units in polyimide and electron-rich dihydroxynaphthalene was developed. CT complex hybrid films whose physicochemical properties, such as mechanical strength, differed from those of the original polyimide films were successfully fabricated. A versatile post-modification method for polyimides using CT complex formation between electron-deficient naphthalenediimide units in the polyimide and electron-rich dihydroxynaphthalene was developed. The film preparation by CT complex formation reported in this paper is an attractive method for functionalization of polyimides because many donor molecules and polyimides can be used. The supramolecular methodology shown here is quite simple, but is an innovative method for polyimide modification.

Theory of modified thermally stimulated current and direct determination of trap level distribution

In order to investigate the trap level distribution in polymer films, a new method is proposed based on modified thermally stimulated current (TSC) theory and numerical calculation of the TSC measurement. In this method, a new function is defined to weight the contribution of every trap level to the external current. The demarcation energy is used to study the trap emptying process. The modified TSC theory shows that only the electrons with trap levels very close to the demarcation energy can significantly contribute to the external circuit at any instant temperature. Based on this method, the trap level distribution of the DuPont original polyimide film 100HN and nanocomposite polyimide film 100CR are investigated as an application example. The effectiveness of the method is confirmed by the experiments. The experimental results show that the trap level density in the 100CR PI films is about six times larger than that in the 100HN PI films through the investigated trap level ranges 06–1.3 eV. The increased traps in 100CR should be introduced by nanofillers, probably come from the interfaces formed between nanofillers and the polymer matrix.

Synthesis and Characterization of Borax‐Polyimide for Flame Retardant Applications

AbstractPolyamide‐borax composites were prepared from solution of polyimide and the borax using N‐methyl‐2‐pyrrolidone as a solvent. The Polyimide‐borax composites films (PI‐BX) characterized by FTIR, SEM and x‐ray. The borax content significantly influences thermal behavior of the polymeric films, such as glass transition and decomposition temperatures of polyimide‐borax composites. The glass transition temperatures of the composites were higher than that of the original polyimide. The flammability properties of them were demonstrated by cone calorimeter and indicate that the borax composites have significantly decreased in heat release rate, and mass loss rate. The PI‐BX composites appears very good the flame retardant properties.

Removal of Ar+ beam‐induced damaged layers from polyimide surfaces with argon gas cluster ion beams

AbstractAn Ar Gas Cluster Ion Beam (GCIB) has been shown to remove previous Ar+ ion beam‐induced surface damage to a bulk polyimide (PI) film. After removal of the damaged layer with a GCIB sputter source, XPS measurements show minor changes to the carbon, nitrogen and oxygen atomic concentrations relative to the original elemental bulk concentrations. The GCIB sputter depth profiles showed that there is a linear relationship between the Ar+ ion beam voltage within the range from 0.5 to 4.0 keV and the dose of argon cluster ions required to remove the damaged layer. The rate of recovery of the original PI atomic composition as a function of GCIB sputtering is similar for carbon, nitrogen and oxygen, indicating that there was no preferential sputtering for these elements. The XPS chemical state analysis of the N 1s spectra after GCIB sputtering revealed a 17% damage ratio of altered nitrogen chemical state species. Further optimization of the GCIB sputtering conditions should lead to lower nitrogen damage ratios with the elemental concentrations closer to those of bulk PI. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Preparation of Polyimide-Clay Nanocomposites and Their Performance

A series of polyimide (PI)-organically modified clay nanocomposites were made to enhance tensile modulus, thermal stability of PI. PI was made from 3, 3', 4, 4'-biphenyl tetracarboxylic dianhydride (BPDA), p-phenylediamine (PDA). Montmorillonite (MMT), one type of layered clay, was treated by dodecylamine salt. XRD indicated that organically modified montmorillonite (OMMT) layers were exfoliated and dispersed into PI-film. Tensile measurements indicated that small amount of OMMT (up to 3%) increased tensile modulus nicely. The glass transition temperatures (Tg) of the nano-composites are higher than those of pristine PI. Thermal gravimetric analysis (TGA) showed that nanocomposites have higher decomposition temperatures in comparison with the original PI. Keywords: Polyimide; Organically modified clay; Nanocomposites; Dodecylamine. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i2.2297

Structural changes and development of transport properties during the conversion of a polyimide membrane to a carbon membrane

AbstractKapton®100HN polyimide membranes were heat treated at temperatures ranging from 623 to 1073 K. The precursor and the heat‐treated membranes were characterized by thermogravimetric analysis, X‐ray diffraction, Raman spectroscopy, density measurement, nitrogen adsorption at 77 K, and single gas permeation. Compared with the precursor, the X‐ray diffraction patterns did not change greatly when the membranes were heat treated at 623–748 K. The membranes treated at 623–723 K showed similar gas permeation rates as the original polyimide membrane whereas those treated at 773–873 K showed remarkable increases in the gas permeances due to the decomposition of the polyimide. Two minimum ideal selectivities were found for the membranes treated at 673 and 723 K. An increase in the temperature from 873 to 1073 K increased the crystallinity and decreased the interplanar spacing in the carbon membranes which had microporous structures as shown by their Type I adsorption isotherms. The membranes treated at 773 K were deemed to be at an intermediate stage between polymer and amorphous carbon. By increasing the temperature from 773 to 873 K, the polyimide changed to a carbon membrane. The gas permeances for He, CO2, O2,N2, and CH4 were increased from 1.06 × 10−9, 1.10 × 10−9, 1.90 × 10−10, 5.70 × 10−11, and 5.55 × 10−11 to 2.68 × 10−8, 3.62 × 10−8, 9.98 × 10−9, 1.66 × 10−9, and 5.17 × 10−10 mol/(m2 s Pa), respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The modification of mechanical properties by 2 MeV Si ions irradiating polyimide

The modification of mechanical properties of polyimide (PI) films by 2.0MeV Si ions irradiation was investigated by means of Hysitron TriboIndenter In Situ Nanomechanical Test System (Hysitron TriboIndenter). The results indicate that the elastic modulus and the hardness have remarkable increase with the increase of the fluence. The elastic modulus of the modified PI at the fluence of 1.25×1015ions/cm2 is nearly five times that of the original PI, and the hardness of the modified PI at this fluence is more than 13 times that of the original PI. The friction coefficient changed from about 0.7 (original PI) to about 0.18 (modified PI at the fluence of 1.0×1015ions/cm2). Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy were applied to analyze the changes in the chemical structures.

Preparation and Characterization of Polyimide/BaTiO&lt;sub&gt;3&lt;/sub&gt; Nanocomposite Films with Lower Infrared Emissivity

The silicon-containing polyimide/BaTiO3 nanocomposite films were prepared by mixing the silicon-containing poly(amic acid) based on bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride and 4,4'-Oxydianiline with BaTiO3 nanoparticles, followed by thermal imidization. Structure and properties of the nanocomposite films were measured with FTIR, SEM, XPS and DMTA. The results indicated that the interfacial interaction between BaTiO3 nanoparticles and the silicon-containing polyimide was conspicuous, and that BaTiO3 nanoparticles appeared to be better dispersed in the polyimide matrix at a higher BaTiO3 concentration than at a lower one. The siliconcontaining polyimide/BaTiO3 nanocomposite films exhibited higher storage modulus and glass transition temperature than the original polyimide. It was also found that the infrared emissivity of the nanocomposite films varied with the content of BaTiO3 in the nanocomposites, and the nanocomposite films exhibited lower infrared emissivity value than the corresponding polyimide by measure of infrared emissivity.

Surface characterization, modification chemistry, and separation performance of polyimide and polyamidoamine dendrimer composite films.

6FDA-polyimide films modified by polyamidoamine (PAMAM) dendrimers with generations of 0, 1, and 2 are reported in this article. The actual molecular conformation and bulk size of these three generation dendrimers immobilized on polyimide surface were characterized by atomic force microscopy. After comparing with the results of dynamic simulation, we believe that the disk-shape cluster structure of dendrimers has been developed on the polymer surfaces. The amidation and cross-linking reaction between dendrimers and polyimide were examined and quantified by X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and gel content measurements. Modification time and the generations of PAMAM dendrimer have been verified as two important factors in determining the properties of modified polyimide films. These modified polyimide films exhibit excellent gas separation performance. The ideal selectivity of He/N(2) increases tremendously to about 200% as compared to that of the original polyimide film. Particularly, the separation performance of CO(2)/CH(4) gas pair can be improved beyond the upper bond limit possibly due to the strong interactions of dendrimer molecules with CO(2), which was verified by sorption tests.

Studies on thermal and mechanical properties of polyimide–clay nanocomposites

Nanocomposites from polyimide and clay were prepared aiming at finding a promising method for enhancing particularly the tensile modulus of polyimide films. Polyimide–clay hybrids were prepared by blending of poly(amide acid) and organically modified-montmorillonite (OMMT) as a type of layered clays. Poly(amide acid) was prepared from the reaction of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA). Also, poly(amide acid) from pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) was prepared for comparison. OMMT was prepared by surface treatment of montmorillonite (MMT) with ammonium chloride salt of 12-aminolauric acid. XRD indicated that the OMMT layers were exfoliated and dispersed into the poly(amide acid) and polyimide film. Tensile properties measurements of polyimide–clay hybrids indicated that the addition of 2 wt.% of OMMT increased the tensile modulus of BPDA/PDA polyimide up to 12.1 GPa, which is ca. 42% higher than the pristine BPDA/PDA polyimide. Tensile modulus of PMDA/ODA also increased up to 6.2 GPa, which is ca. 110% higher than that of the original PMDA/ODA polyimide. The glass transition temperatures of the BPDA/PDA nanocomposites were higher than that of the original polyimide. The thermal expansion coefficient of the BPDA/PDA polyimide film decreased by the inclusion of clay. Isothermal and dynamic TGA showed that the both types of polyimide nanocomposites have higher decomposition temperatures in comparison with the original polyimides.