Polyimide Research Articles

Enhancing Zinc Electrode Stability Through Pre-Desolvation and Accelerated Charge Transfer via a Polyimide Interface for Zinc-Ion Batteries.

Aqueous zinc-based energy storage devices possess superior safety, cost-effectiveness, and high energy density; however, dendritic growth and side reactions on the zinc electrode curtail their widespread applications. In this study, these issues are mitigated by introducing a polyimide (PI) nanofabric interfacial layer onto the zinc substrate. Simulations reveal that the PI nanofabric promotes a pre-desolvation process, effectively desolvating hydrated zinc ions from Zn(H2O)6 2+ to Zn(H2O)4 2+ before approaching the zinc surface. The exposed zinc ion in Zn(H2O)4 2+ provides an accelerated charge transfer process and reduces the activation energy for zinc deposition from 40 to 21kJ mol-1. The PI nanofabric also acts as a protective barrier, reducing side reactions at the electrode. As a result, the PI-Zn symmetric cell exhibits remarkable cycling stability over 1200h, maintaining a dendrite-free morphology and minimal byproduct formation. Moreover, the cell exhibits high stability and low voltage hysteresis even under high current densities (20mA cm-2, 10 mAh cm-2) thanks to the 3D porous structure of PI nanofabric. When integrated into full cells, the PI-Zn||AC hybrid zinc-ion capacitor and PI-Zn||MnVOH@SWCNT zinc-ion battery achieve impressive lifespans of 15000 and 600 cycles with outstanding capacitance retention. This approach paves a novel avenue for high-performance zinc metal electrodes.

Compositionally engineered amorphous InZnO thin-film transistor with high mobility and stability via atmospheric pressure spatial atomic layer deposition

Amorphous indium-zinc oxide (IZO) thin films, featuring indium atomic concentrations between 35.2 and 64.2 at.%, were fabricated using atmospheric pressure spatial atomic layer deposition (AP S-ALD) at 250 °C, employing trimethylindium (TMI) and diethylzinc (DEZ) as precursors and ozone as the reactant, based on the atomic layer processing. The crystallinity and chemical bonding states of the IZO films were found to vary with the metal cation composition, as confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). We fabricated thin-film transistors (TFTs) employing the IZO films as the active layer on polyimide (PI) substrates, achieving high mobility (45.7 cm2/V·s), excellent bias-temperature stress (BTS) stability (ΔVTH = 0.63 V), and maintaining stable electrical properties even after mechanical bending tests along two different axes. This study highlights the successful development of high-performance flexible devices by precisely controlling the metal cation composition using AP S-ALD based on high deposition rate.

Compact Monoenergetic Proton Generator in MeV Region Using NANOGAN

For simple applications, such as the calibration of a charged particle detector, a multi-MeV proton generator may be preferable to cyclotrons or electrostatic accelerators such as Van de Graaff. Thus, a compact proton generating system, consisting of 10Ghz ECR ion source NANOGAN and a deuteron target, was developed at the Research Center for Nuclear Physics at Osaka University. A 3He2+ beam was generated by the NANOGAN with the acceleration voltage of 20∼45 kV in an experiment that utilized the fusion reaction 3He + deuteron (d) → proton(p) + 4He. The monochromatic protons with energies of 14.67 MeV were successfully obtained at the atmosphere side of the target in the experimental setup, when a novel target base with a thin metal foil and Polyimide film window are used.

Flexible laser-induced graphene electrodes on polyimide film: Hybrid nanoflower-modified dielectric microjunctions for non-faradaic analysis

Laser-induced Graphene (LIG) electrodes on flexible substrates have attracted significant research interest, making them an excellent alternative to conventional fabrication of transducers on rigid planar substrates. In this study, four individual capacitor-like triangular LIG electrodes were fabricated on polyimide (PI) film with micron gap (MG) spacing of 30, 66, 125 and 180 µm, to study the relationship between gap spacing and capacitance. A novel N, N-carbonyldiimidazole-copper (CDI-Cu) hybrid nanoflower (NF) was synthesised via one-pot biomineralization and deposited at the triangular junction of acid-base treated LIG-MG for the immobilization of neutravidin. The gap spacing and structure of the LIG-MG were analysed using high-resolution microscopes, revealing a porous nanofiber-like graphene structure. X-ray Photoelectron Spectroscopy (XPS) of acid-base treated PI film proved carboxyl group formation. A decrease in capacitance was observed with an increasing gap spacing in a non-faradaic environment. The capacitance of CDI-Cu NF following neutravidin modification for 30, 66, 125 and 180 µm spacings were 1.77E-07, 1.36E-07, 4.73E-08, 4.84E-08 F, respectively, suggesting excellent biomolecular modification sensitivity of the LIG-MG with 30 µm spacing. A comparative analysis of dielectric performance for different gap-spaced devices revealed that a 30 µm spacing would be optimal for bio-capturing because of the close confinement of biomolecules for smaller gapped areas.

Fabrication of Laser-Induced Graphene on Carbon Electrodes for Efficient Hydrogen Evolution Reaction

Hierarchical porous carbon materials have received significant attention for application in catalytic water splitting because of their high efficiency, cost-effectiveness, and biocompatibility. In this study, laser-induced graphene (LIG) was fabricated on a carbon film- (CF-) type substrate for an efficient hydrogen evolution reaction (HER). The LIG-CF electrode was fabricated via laser-induced graphitization on a commercial polyimide (PI) film, followed by the pyrolysis of the LIG on the PI film (LIG-PI). During pyrolysis, the microscopic and material properties of the LIG remained intact, as verified through various characterizations. The as-prepared all-carbon electrode was then utilized as an electrode for the HER study in a 1.0 M KOH electrolyte and compared with LIG-PI and Pt electrodes. In the HER experiments, the optimized LIG-CF electrode exhibited excellent catalytic performance with zero-onset potential, and the potentials required to achieve high current densities of 10 and 20 mA/cm2 were 134 and 139 mV (vs. reversible hydrogen electrode (RHE)), respectively. The excellent performance of the LIG-CF electrode originates from the hierarchical porous structure of the LIG material, which serves as an electrochemically active site, and carbon substrate that facilitates the fast transport of ions at the electrode/electrolyte interface. Additionally, the carbon substrate shortens the transportation length of electrons which played a significant role for the enhanced performance of the LIG-CF electrode.

Backside bonding for extremely narrow bezel at the bottom of flexible displays

AbstractWe developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65°C) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the next‐generation flexible displays.

Highly flexible porous indium-tin-oxide coating with enhanced atomic oxygen and electrostatic discharge resistance

Polyimides (PI) are commonly used in spacecraft in low Earth orbit (LEO) due to their flexibility. However, they are susceptible to erosion caused by atomic oxygen (AO) and electrostatic discharge (ESD) induced by plasma in the harsh LEO environment. Indium-tin-oxide (ITO), owing to its excellent electrostatic and AO resistance, has emerged as the most promising inorganic protective coating for PI in LEO applications. But the inherent rigidity of ITO and the high-temperature annealing process commonly required for synthesis make it challenging to employ ITO as flexible polymer substrates. In this work, we have synthesized the porous ITO layer with a low-temperature (≤150 °C) method and combined it with layer double hydroxides (LDHs) to enhance the flexibility, AO resistance, and ESD protection of the coating. The porous ITO in combination with LDHs layers effectively improve the flexibility (after 20,000 bending cycles without failure problem), AO resistance (erosion yield down to -0.102 × 10−26 cm3/atom under an exposure dose of 5.22 × 1021 atoms/cm2) and ESD resistance properties (sheet resistance around 202 kΩ/sq). The synthesis method proposed avoids the high-temperature annealing and the residual stress effect on the coating's flexibility. This work provides an efficient approach to realizing flexible and protective coating on polymers for long-lasting spacecraft electronic devices in low Earth orbit.

Controlling Fluorination Density of Soluble Polyimide Gate Dielectrics and its Influence on Organic Crystal Growth and Device Operational Stability.

Fluorinated polyimides (PIs) are among the most promising candidates for gate dielectric materials in organic electronic devices because of their solution processability and outstanding chemical, mechanical, and thermal stabilities. Additionally, fluorine (F) substitution improves the electrical properties of PI thin films, such as enhanced dielectric properties and reduced surface trap densities. However, the relationship between the fluorination density of PIs and crystal growth modes of vacuum-deposited conjugated molecules on PI thin films, which is directly related to the lateral charge transport along the PI-organic semiconductor interface, has not been systematically studied. Herein, five different soluble PIs with different F densities were synthesized, and the correlation between fluorination and thin-film properties was systematically investigated. Not only were their dielectric properties modulated, but the growth modes of the organic molecules deposited on the PI thin films also changed with increasing surface F density. This phenomenon was observed by both surface and crystallographic analyses, which resulted in extremely high operational stability of field-effect transistors and the successful fabrication of organic complementary circuits. We believe that the correlation between PI backbone fluorination and its thin-film properties will provide practical insights into the material design based on controlled molecular directed surface assembly on fluorinated polymer dielectrics.

Examining differences in the uptake of corrosive gases in polymer films and its dependence on temperature and relative humidity using a novel procedure combining sample weathering and LA-ICP-MS analysis

In polymer coating applications for technological products exposed to harsh environmental operating conditions, it is essential to provide and extend the protection capability of the coating material against corrosive gases, such as hydrogen sulfide or sulfur dioxide. Therefore, applied materials are subject to ongoing developments to improve their properties. Such developments aiming to establish improved polymer materials can only be performed accompanied by suitable testing procedures and analysis methods, for which a versatile approach is proposed in the presented work.We developed a testing approach, combining a mixed flowing gas setup (MFG) that allows flexibly adjustable exposure conditions for weathering experiments, and laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) for subsequent sample analysis, allowing quantitative and spatially resolved determination of the sulfur uptake derived from H2S or SO2 weathering with high sensitivity. The testing procedure is demonstrated on four different polymer types – polyimide (PI), polyvinylpyrrolidone (PVP), polystyrene (PS), and polyvinylacetate (PVA). Results from bulk measurements showed a significantly higher uptake of SO2 compared to H2S, and that the uptake increases with higher exposure temperatures and relative humidity levels. Further, quantitative sulfur depth profile measurements reveal diffusion profiles into the polymer films. The gas uptake was observed mostly withing the uppermost 1–2 µm of the surface, with quickly decreasing concentrations into the bulk of the materials. However, strong variations of the spatial distribution of sulfur between the different polymer types and between different exposure conditions were determined. The results provided give a good insight into what possibilities the proposed investigation procedure opens up for specifically dedicated research compared to standard methods that are used to determine gas permeation.

Construction of polyimide composite aerogels via multi-coordination structure of polymer-metal for improving heat-induced shrinkage, thermal insulation, mechanical and dielectric properties

The fabrication of polyimide (PI) composite aerogels can promote and optimize the characteristics and performance efficiency. But in fact, interface effect and assembly technique are the key problems in preparing PI composite aerogels. To settle this critical issue, a series of PI composite aerogels were designed via forming multi-coordination structure between PI molecular chain and Cu(II) metal ions. Multi-coordination structure connects the two-phase systems closely to obtain the improved comprehensive performances. The resulting PI composite aerogels still have high specific surface and mesoporous structure. The addition of Cu(II) improves the thermal and mechanical properties of the PI composite aerogels with an over 581 °C initial decomposition temperature, tensile strength of up to 9.48 MPa and modulus of up to 232.4 Mpa，along with compression Young’s modulus increased by 173% (up to 28.7 MPa) and stress at 10% strain improved by 150% (up to 1.70 Mpa). In the meantime, the brilliantly controllable dielectric property (with the dielectric constant down to 1.60 and the dielectric loss reaching 0.0171 at 10 MHz) and thermal insulation property (with the thermal conductivity down to 31.9 mWm−1K−1) of PI composite aerogels make them can be used as low dielectric and thermal protection materials. The small heat-induced shrinkage between 100 and 250 °C allows the PI composite aerogels to operate in persistent extreme conditions. Besides, this work can provide a new strategy for preparing PI composite aerogels.

Laser-assisted synthesis of MnOx and 3D graphene composites for wide-voltage flexible planar microcapacitors

Herein, we propose a simple and eco-friendly strategy based on laser direct writing technology to regulate the valence state of Mn-based oxides nanoparticles anchored on three-dimensional(3D) framework of laser-induced graphene (LIG) for the application of high-performance flexible planar interdigital microsupercapacitors (MSCs). Under the laser radiation, a polyimide (PI) and MnO2 composite film was directly converted into 3D graphene and MnOx (MnO, MnO2 and Mn3O4 mixture). Furthermore, the results reveal that LIG/MnOx MSCs device exhibits a high specific capacitance of 23.3 mF cm−2, which is about 29 times higher than that of LIG MSCs (0.8 mF cm−2). Moreover, LIG/MnOx MSCs possess a high energy density of 7.28 μWh cm−2, outstanding cycle stability with the capacitance retention rate of 97.4 % after 10,000 cycles, and excellent mechanical flexibility. Therefore, this preparation strategy of LIG/MnOx provides a reference for the performance regulation of Mn-based oxides and the low-cost construction of MSCs devices with high energy density, which carries significant research implications for diverse flexible wearable electronic applications in the forthcoming days.

A sulfonated polyimide containing imidazole ring with a low vanadium ion permeable for vanadium redox flow battery

A new type of sulfonated polyimide membrane (6f-abSPI) containing benzimidazole group and trifluoromethyl group (-CF3) is synthesized by one-step copolymerization. The 6f-abSPI-60 membrane with the highest ion selectivity is selected and applied to all vanadium redox flow battery (VRFB). Compared with Nafion 212 (N212) membrane and 6f-SPI-60 membrane, the vanadium ion permeability of 6f-abSPI-60 membrane (1.78 × 10−7 cm2 min−1) is 1/13 lower than that of N212 membrane (2.33 × 10−6 cm2 min−1) and 1/2 lower than 6f-SPI-60 membrane (3.60 × 10−7 cm2 min−1). At the same time, the 6f-abSPI-60 membrane (2.69 × 105 S min cm−3) has significant selectivity, which is 5.6 times higher than N212 membrane (0.48 × 105 S min cm−3). In VRFB tests, the coulombic efficiency (CE) of 6f-abSPI-60 membrane (98.88 %) is significantly higher than that of N212 membrane (92.99 %) and 6f-SPI-60 membrane (97.65 %) at 100 mA cm−2, and the energy efficiency (EE) also reaches a higher value (77.29 %). Additionally, the VRFB equipped with the 6f-abSPI-60 membrane exhibits consistent and reliable performance throughout the 100 cycles of charging and discharging at the current densities of 100 mA cm−2. The good stability of 6f-abSPI membranes is explained by calculating C atoms’ natural bond orbital (NBO) charges on different polyimide (PI) rings.

A microfluid-on-microfluid phase separation strategy fabricates high-throughout porous polyimide separator for lithium-ion batteries

The microstructures and thermal stability of separators are critical for the safety and performance of lithium-ion batteries; however, it is still challenging to fabricate advanced separators simultaneously achieving uniform and high-throughput interconnected microporous structures with high thermal stability. Here, based on a soluble polyimide (PI) with high thermal stability, we report a microfluid-on-microfluid phase separation strategy (MF2-PS) to address the above challenge. Compared to the traditional non-solvent induced phase separation by immersion, the MF2-PS strategy can achieve more controlled porous structures with sponge-like open channels at submicron scale. The high surface polarity of the PI-separator also exhibited good wettability with liquid electrolytes, and a high electrolyte uptake (182 wt%) for achieving a high ion-conductivity. It also showed much superior thermal stability as compared to PP separator. Finally, due to the unique porous structures, the PI-separator by MF2-PS strategy successfully delivered a discharge capacity of 161.9 mA h g−1 for LiFePO4 electrode, and very stable cycling performance. All these results indicates that the PI-separator by MF2-PS may find significant applications in safe and high-performance batteries.

Foldable polyimide/ionic liquid composite films with high transmittance and ultraviolet resistance benefiting from the intermolecular multipoint interaction

A foldable polyimide (PI) protective layer with high transmittance and high ultraviolet (UV) resistance is crucial for the practical application of flexible solar cells. Herein, the commercially 2,2′-Bis(trifluoromethyl) benzidine (TFMB) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as the monomers, and five ionic liquids (ILs) as the regulators were used to synthesize PI/IL films (PI/IL1, PI/IL2, PI/IL3, and PI/IL4). The outcomes reveal that the average transmittance (AT) of PI/IL1 (50 μm thickness) outperforms others, which can be attributed to the expanded π-π stacking distance between PI molecules and the intermolecular multipoint interaction between IL1 and PI. The AT and the elongation at break (ε) of PI/IL1 increase sequentially with the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2])/TFMB mole ratio, and those of PI/IL1-3 reach the maximum values of 94.23 % and 49.42 % at a 3:1 ratio, respectively. However, the tensile strength (σ) of the PI/IL1 film is inferior to that of the pure PI film, and consistently decreases with the increase of [C2mim][NTf2]/TFMB mole ratio. Nevertheless, the UV-induced degradation of PI can be delayed through the [C2mim][NTf2] regulation. The attenuations of AT, σ and ε of PI/IL1-3 films after 1000 equivalent solar hours (ESHs) UV irradiation are 0.85 %, 14.63 % and 2.99 %, respectively, which are significantly lower than those of pure PI films (2.23 %, 32 % and 23 %). This is attributed to the interaction between the positive and negative charges from [C2mim][NTf2] and those from the PI chain breaking. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of PI/IL1-3 are calculated with the density functional theory to reveal the charge transfer between [C2mim][NTf2] and PI.

POLYIMIDE FILMS IMPLANTED BY MANGANESE IONS

The optical and strength properties of Kapton polyimide films implanted with manganese ions with an energy of 40 keV and a dose of 5·1016 – 1·1017 cm–2 at a current density in the ion beam of 4 μA/cm2 have been studied. It has been experimentally established that during the process of ion implantation, modification of a thin nearsurface layer of polyimide occurs not only on the implanted side, but also on the reverse side of the film. Radiationstimulated modification of the back surface of the polyimide film leads to the formation of a surface layer up to 5 μm thick with increased microhardness. This may be due to the restructuring of metastable defects formed during the film manufacturing process and the simultaneous relaxation of elastic stresses in the surface layer. During the implantation process, a decrease in the intensity of absorption bands with maxima at ~ 2870 and ~ 2750 nm is observed, due to the evaporation of residual water under high vacuum conditions and reactions of residual solvent molecules, as well as radiation-induced processes on by-products of polyimide synthesis.

ELECTRON IRRADIATED PI2610 POLYIMIDE FILMS ON MONOCRYSTALLINE SILICON

The optical and strength properties of electron-irradiated films of a polyimide composition (polyimide PI2610) deposited on the surface of single-crystalline silicon wafers of the KDB-10 grade by centrifugation were studied. Irradiation with electrons with an energy of 5 MeV was carried out on a linear accelerator U-003 in the dose range 1·1014 – 2·1015 cm–2. It has been experimentally established that at an irradiation dose of Ф = 1∙1014 cm–2, relaxation of elastic stress fields in the polyimide film is observed, which is expressed in modification of the shape of bands with maxima at 1349 and 1700 cm–1, caused by vibrations of the C–N–Cst bond and the C=O double bond imide ring. Polyimide PI-2610 films on silicon are quite stable when irradiated with electrons. A noticeable transformation of the ATR spectrum at a dose of 2∙1015 cm–2 was observed only in the region of stretching vibrations of C–H and O–H bonds, which is due to radiation-induced processes on by-products of polyimide synthesis and residual solvents. No noticeable decrease in the intensity of absorption bands caused by vibrations of the skeleton of the aromatic ring, imide ring, single and double C–C and C–O bonds, and imide C=O bonds was observed.

Dual-functional Separators Regulating Ion Transport Enabled by 3D-Reinforced Polyimide Microspheres Protective Layer for Dendrite-Free and High-Temperature Lithium Metal Batteries.

High-energy-density lithium metal batteries (LMBs) are confronted with crucial concerns of security and a short cycle lifespan caused by the uncontrollable formation of lithium (Li) dendrites. The poor thermal stability and heterogeneous Li deposition of conventional polyolefin separators often cause battery short circuiting and thermal runaway in LMBs. Herein, a novel dual-functional PE composite separator (PI-COOH/PE) coated by carboxyl polyimide (PI) microspheres is fabricated by an etching-acidification method. The three-dimensional (3D) high-temp PI microsphere with rich carboxyl groups on the surface improve the security of LMBs at extremely high temperatures and facilitate the formation of a stable and uniform SEI layer, which contributes to accelerating the Li+ transport and stabilizing the formation of the SEI layer. Consequently, the Li symmetric cell assembled with the (PI-COOH)/PE separator exhibits stable overpotential over 3000 h, and the corresponding Li//NCM811 full cells also show a high-level discharge capacity of 146.6 mAh g-1 at 5 C. Meanwhile, it also demonstrates outstanding cycling stability and thermal safety, which can survive continuously over 160 min at 140 °C (vs 21 min for PE). The above results indicate the (PI-COOH)/PE separator constructed by a low-cost and industrial-friendly strategy simultaneously addresses high-temperature stability and dendrite resistance.

Synthesis of micro/nano multi-scale polyimide aerogels via confinement-controlled freeze-casting

The freeze-casting is widely utilized as a tool for regulating micro-scale pore structures in the fabrication of flexible polyimide (PI) aerogels for applications in adsorption, filtration, and fire-retardant. Herein, a confinement-controlled freeze-casting method is developed to fabricate PI aerogels with excellent thermal insulation properties by designing multi-scale structural adaptability. In a confinement-controlled system, the enhanced solid/solid and solid/liquid interface interactions in the solution dispersion system induce dendritic evolution of ice crystals. Under the directional freezing, grown dendritic ice crystals squeeze the loaded particles to form polyamic acid salt (PAAs) cryogels. Followed by template removal and thermal imidization, PI aerogels with a micro/nano-scale slit-like porous structure were obtained. The PI aerogels are characterized by ultra-low density (as low as 9.82 mg/cm3) and exceptional thermal insulation performance (25.0 mW/(m·K) at 25 °C).

Performance evaluation of flexible thermoelectric generator with Bi2Te3 thin-film

In the information society, carrying devices such as smartphones and tablets is crucial, and ensuring their power supply is essential. Furthermore, from the perspective of energy security, being able to secure their power supply from low-quality energy sources could reduce dependence on fossil fuels. In this study, we fabricated a flexible thermoelectric generator capable of harvesting energy from a low-temperature difference between a low-temperature heat source and room or outdoor temperature and evaluated its performance. The device was fabricated by depositing an n-type Bismuth telluride (Bi2Te3) film onto a polyimide film substrate using radio frequency (RF) magnetron sputtering. A 3D printer was used to fabricate flexible fins for attaching and bonding the films. Owing to their adaptability, these flexible models can be installed on heat sources of different shapes. The experimental conditions for this study were as follows: the temperature in the test chamber was maintained at 25 ± 1 °C and that of the heat source ranged from 35 to 75 °C; further, thermoelectric elements in numbers varying from 1 to 6 were installed. The maximum open-circuit output voltage |E| and power generation (Pmax) were determined to be 11.4 mV and 69 nW, respectively. The fins with the Bi2Te3 thin film maintained a temperature of approximately 25 to 30 °C at the tip of the fin, even when exposed to the highest temperature (75 °C) of the heat source during the experiment. As a result, the thermoelectric device developed in this study has demonstrated the potential to power sensors operating in the tens of nW range.

Crown Ether Copolymerized Polyimide Film: Enhanced Mechanical, Thermal Properties and Low Dielectric Constant under High Frequency.

Polymer materials with a low dielectric constant and low dielectric loss have the potential to be applied to high-frequency signal transmissions, such as mobile phone antennas and millimeter wave radars. Two types of diamines, 4,4'-diamino-p-tetraphenyl (DPT) and crown ether diamine (CED), were prepared for ternary copolymerization with BPDA in this study. Cross-links with molecular chains were formed, increasing molecular chain distance by utilizing rings of CED. The MPI films exhibit a good thermal performance with the increase in CED addition, with Tg > 380 °C and CTE from -4 × 10-6 K-1 to 5 × 10-6 K-1. The Young's modulus can reach 8.6 GPa, and the tensile strength is above 200 MPa when 5% and 7% CED are introduced. These MPI films exhibit good mechanical performances. The dielectric constant of PI-10% film can go as low as 3.17. Meanwhile, the relationship between dielectric properties and molecular structure has been demonstrated by Molecular Simulation (MS). PI molecules are separated by low dielectric groups, resulting in a decrease in the dielectric constant.