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Polyimide (PI) is one of the most important engineering plastics, but its stability in aqueous environments is insufficient, which limits its anti‐corrosion efficiency. In this study, a novel P(VDF‐HFP)/SMT‐RS@BNNSs/PI composite coating is prepared by incorporating poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF‐HFP)) and the exfoliated boron nitride nanosheets (BNNSs) which were highly co‐functionalized with two kinds of materials of the rosin and the soy‐maleic anhydride‐tannic acid adhesive molecules (SMT‐RS@BNNSs). The coatings are characterized in detail by using the XRD, FT‐IR, XPS, and SEM technologies. Electrochemical impedance spectroscopy (EIS) and polarization curve tests further evaluated the corrosion resistance of the coating. As results, the obtained P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating with good adhesion (grade 1) to the low‐carbon steel plate displays a larger water contact angle of 93.10° compared to blank PI (75.5°) and SMT‐RS@BNNSs/PI (83.2°). The dispersed distribution and interaction of SMT‐RS@BNNSs can effectively reduce the phase separation between P(VDF‐HFP) and PI. Even after soaking in electrolyte for 15 days, the impedance modulus, corrosion current, and corrosion voltage of the P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating are 1.568 × 1010 Ω cm2, 4.612 × 10−12 A cm−2, and 0.325 V, respectively. These properties are superior to those of the PI and SMT‐RS@BNNSs/PI coatings. It is believed that the excellent anti‐corrosive performance of this PI‐based composite will broaden the application fields of PI materials. [ABSTRACT FROM AUTHOR]

The preparation of polyimide matrix composites with low curing temperature and high mechanical properties is of great importance. In this study, a low‐cost and multi‐functional nanofiller, 5‐aminobenzimidazole grafted graphene oxide (5‐ABZ@GO) has been designed. By nucleophilic attack on 5‐aminobenzimidazole basic groups and doping of GO, the above requirements of polyimide composites were skillfully realized. The results show that when the addition of 5‐ABZ@GO is 1%, the 5‐ABZ@GO/PI nanocomposites can achieve complete imidized at 200°C. Moreover, the nanocomposite prepared by imidization at 200°C has good mechanical and thermal properties (tensile strength is 141.64 MPa, modulus is 6.05 GPa, T5% is as high as 543.5°C), which is better than the PI composites prepared at 320°C. This study provides an innovative approach to preparing polyimide composites that meet mechanical performance requirements while utilizing comparatively lower curing temperatures, low curing temperature polyimide resins provide a new path for integrated composites with structure–function integration. [ABSTRACT FROM AUTHOR]

This study endeavors to enhance the safety of lithium‐ion batteries (LIBs) by synthesizing a polyamide acid (PAA)/Al2O3 composite spinning solution using 4,4′‐diaminodiphenyl ether (ODA) and pyromellitic anhydride (PMDA) as monomers, and nano‐Al2O3 as a thermal conductivity filler. Subsequently, the PAA/Al2O3 fiber membrane is fabricated via electrostatic spinning, followed by gradient heating imidization to produce a polyimide (PI)/Al2O3 composite membrane. This membrane is then dipped into a boron nitride (BM) slurry to ultimately yield an organic–inorganic PI/Al2O3/BM composite separator with superior flame‐retardant and thermal conductivity properties. The thermal stability, flame retardancy, electrolyte wettability, mechanical integrity, and cycle rate performance of the composite membranes are rigorously evaluated. The results demonstrate that the PI/5% Al2O3/BM composite membrane exhibits the most favorable overall performance, with no shrinkage observed at 200°C and no significant changes after sustained ignition for 10 s. The incorporation of the thermal conductivity Al2O3 filler significantly enhances the heat transfer properties of the composite separator. The room temperature ionic conductivity reaches 2.786 mS cm−1 after electrolyte absorption, and the initial discharge capacity of the assembled battery is 156.28 mAhg−1. Following 100 charge/discharge cycles at 0.2C, the capacity retention rate is 97.7%, and at a discharge rate of 5C, the capacity retention rate is 74.9%. [ABSTRACT FROM AUTHOR]

AbstractWith the rapid development of 5 G technology and microelectronics, there is an urgent demand to design and develop modified polyimide films with low dielectric constant as flexible matrix materials. In this work, a diamine containing multiple side methyl and biphenyl groups was synthesized by aromatic nucleophilicsubstitution reaction and oxidation-reduction reaction, respectively. Furthermore, this monomer was used to polymerize with four different commercially available dianhydrides (ODPA, BTDA, BPDA, and PMDA) to produce a class of polyimides (PI 3a∼3d). The structures of the diamine and its PIs are characterized, and the relationship between the structure and properties of the obtained PI films is investigated. These modified PIs are easy to cast into films and have low dielectric constants and water absorption. Their dielectric constants and dielectric losses are in the range of 2.66–2.91 and 0.00579–0.00677 at 1 MHz, respectively. Meanwhile, these PIs also maintains good thermal stability, with glass transition temperatures (Tg) higher than 284 °C and 10% weight loss temperatures in the range of 496–505 °C at N2. [ABSTRACT FROM AUTHOR]

Developing advanced engineering polymers that combine high strength and toughness represents not only a necessary path to excellence but also a major technical challenge. Here for the first time a rigid‐flexible interlocking polymer (RFIP) is reported featuring remarkable mechanical properties, consisting of flexible polyurethane (PU) and rigid polyimide (PI) chains cleverly woven together around the copper(I) ions center. By rationally weaving PI, PU chains, and copper(I) ions, RFIP exhibits ultra‐high strength (twice that of unwoven polymers, 91.4 ± 3.3 MPa), toughness (448.0 ± 14.2 MJ m−3), fatigue resistance (recoverable after 10 000 cyclic stretches), and shape memory properties. Simulation results and characterization analysis together support the correlation between microstructure and macroscopic features, confirming the greater cohesive energy of the interwoven network and providing insights into strengthening toughening mechanisms. The essence of weaving on the atomic and molecular levels is fused to obtain brilliant and valuable mechanical properties, opening new perspectives in designing robust and stable polymers. [ABSTRACT FROM AUTHOR]

Ultrahigh molecular weight polyethylene (UHMWPE) fibers possess excellent mechanical properties, yet their applications are severely limited by surface inertness and low melting points. To enhance surface activity and temperature resistance, soluble polyimide (PI) is applied to the surface of UHMWPE fibers. A mussel‐inspired biomimetic polycatechol/polyamine (PA) coating is initially constructed on the UHMWPE fiber surface by oxidative self‐polymerization, serving as a secondary reaction platform. Subsequently, multifunctional UHMWPE‐PA‐PI fibers are prepared by depositing soluble PI on the fiber surface via impregnation. The PA and PI layers are firmly bonded by hydrogen bonding interactions and physical adhesion. The results show that the PI‐coated UHMWPE fiber surface exhibits enhanced chemical activity, hydrophilicity, and thermal stability, with an increased thermal decomposition temperature of approximately 30 °C. Compared to pristine UHMWPE, the breaking force of UHMWPE‐PA‐PI fibers increases by 14.9%, and the interfacial adhesion strength between the fiber and rubber improves by 65.5%. The PI coatings also provide thermal insulation, acid resistance, and erasability functionalities. This modification strategy is highly efficient, simple, and less damaging, offering a novel solution to address UHMWPE fibers' surface inertness and temperature intolerance. [ABSTRACT FROM AUTHOR]

High‐performance thermoplastic composites of polyketones [poly‐aryl‐ether‐ketone (PAEK), poly‐ether‐ether‐ketone (PEEK), poly‐ether‐ketone‐ketone (PEKK)] reinforced with continuous carbon fiber (CF) were consolidated using towpreg produced by multi‐scale aqueous dispersion coating technique. An intra‐matrix trend of composite strength and void fraction was studied to identify the composite with maximum strength free of voids for each polyketone matrix. The CF/PAEK composite with a flexural strength of ~2047 MPa and ILSS of ~99 MPa with a fiber volume fraction of ~67% had the maximum strength free of voids among CF/PAEK composite and all polyketone composites studied. The highest crystallinity (34.5%), and the highest amount of hydrogen bonding and bonds formed between CF, PI nanoparticle, and PAEK explained the origin of strength in CF/PAEK composite. The maximum strength among CF/PEEK and CF/PEKK composite free of voids had a flexural strength of ~1861 MPa, ~1981 MPa; ILSS of ~74 MPa, ~60 MPa; fiber volume fraction of ~61% and ~ 65%, respectively. The polyimide (PI) nanoparticles layer on CF formed the fiber matrix interface, supported hydrogen bonding in all polyketone composites, and formed bonds with CF and matrices of PAEK and PEEK establishing a synergistic effect. Highlights: Intra‐matrix trend of strength and voids in polyketone composites studied.Void‐free, high‐performance, high fiber volume fraction composites developed.CF/PAEK composite had maximum strength among polyketone composites studied.PI nanoparticles formed bonds with CF and matrices of PAEK and PEEK.CF/PAEK composite strength originates from crystallinity, H bond, and bonding. [ABSTRACT FROM AUTHOR]

Polymer composites with heat resistance, good thermal conductivity, and insulation properties can meet the special needs of electronics and electrical appliances. In this work, graphene oxide (GO) and carbon nanotubes (CNTs) are coated by polydopamine (PDA). 4,4′‐diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA), and 4,4′‐oxydiphthalic anhydride (ODPA) in‐situ polymerize to prepare poly(amide acid) (PAA) containing thermally conductive yet insulating fillers (PDA@GO, PDA@CNTs). As the concentration of fillers in PI composites increases, the thermal conductivity rises, but the insulation property decreases. Keeping the filler content constant and varying the ratio of PDA@GO and PDA@CNTs, the thermal conductivity increases and then decreases. When PDA@GO and PDA@CNTs have a mass ratio of 10:1, the significant synergistic effect affects the thermal conductivity. The PI/PG10C1–25 sample has a thermal conductivity of 1.46 W/(m·K), which is 6.9 times greater than the pure PI. Additionally, the volume resistivity, dielectric permittivity, and dielectric loss (100 kHz) of PI/PG10C1–25 are 2.8 × 1013 Ω cm, 5.4 and 0.28, respectively. The heat resistance of PI composites is almost the same as that of pure PI. Given these outstanding attributes, the developed PI composites offer vast applications in many fields. Highlights: Synergistic PDA@GO and PDA@CNTs (10:1) optimize thermal conductivity.PI/PG10C1–25 achieves 6.9 times higher thermal conductivity than pure PI.Volume resistivity of PI/PG10C1–25 reaches 2.8 × 1013 Ω·cm.Dielectric permittivity of PI/PG10C1–25 reaches 5.4 at 100 kHz.Developed PI composites maintain excellent heat resistance. [ABSTRACT FROM AUTHOR]

Reliable long‐term function is crucial for flexible and soft bioelectronics. Mechanical defects and permeation of water molecules across the various device layers are the prime drivers of failure, and particularly in applications requiring continuous contact with biofluids (i.e. for implantable applications). To address demanding needs of miniaturization, mechanical compliance and water impermeability, ultra‐thin high‐barrier encapsulations are a promising way to improve device reliability. In this work, the encapsulation properties of vapour phase infiltration (VPI) of inorganic Al2O3 layers deposited by atomic layer deposition (ALD), as bilayers with TiO2, onto polyimide and parylene C organic substrates are investigated. The layers are grown in a single reactor and the infiltration is performed in a single process, with a resulting nanometric infiltration depth. Mechanical integrity and hermeticity are characterized through tensile fragmentation tests and accelerated aging tests. Flexible Magnesium sensors monitor water vapor permeability in situ. A remarkable improvement in the crack onset strain (∽2.56 times), interfacial shear strength (∽2.1 times), water vapour transmission rate (∽5.2 times) and lifetime performance (∽7.1 times) is achieved, compared to the non‐infiltrated ALD coatings. Pluri‐infiltrated multilayers are proposed as alternatives to conventional coatings. This work is envisioned to accelerate research progress on hermetic packaging of flexible bioelectronics. [ABSTRACT FROM AUTHOR]

Biogas is a type of biomass energy source, primarily composed of methane and carbon dioxide. It is generated through the controlled anaerobic digestion of manure or other organic residues. As a cleaner alternative to conventional fuels, fully purified biogas can produce approximately 36.68 MJ/m3 of en.ergy. As the separation of CO2/CH4 in biogas became an important part of the energy industry, we used membrane separation technique to study its separation methods. At first, 3,3′‐dihydroxy‐4,4′‐diamino‐biphenyl (HAB) and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were polymerized by open‐loop as polyamide acid macromolecules. Then it was divided into two research routes. One was condensation to polyimide (PI) membranes directly and then thermal rearrangement (TR); the other one was ionic liquid (IL) added before condensation and thermal rearrangement. Through adjusting the thermal rearrangement temperature, different modified polyimide membranes were obtained and tested their separation performance of CO2/CH4. For the result of the test, the best one, membrane HAB‐6FDA‐IL‐TR400, could reach a good separation performance as PCO2 = 403.80 Barrer, αCO2/CH4 = 82.35. It was beyond the Robeson's 2019 upper limit and proved that the modification by IL and thermal rearrangement was benefit for the separation performance of polyimide membranes. [ABSTRACT FROM AUTHOR]

Simultaneous detection of multiple neurotransmitters and their related activities is crucial for enhancing our understanding of complex neurological mechanisms and disorders. In this study, we developed a flexible, high-sensitivity multi-electrodes array probe capable of concurrent detection of four neurotransmitters: dopamine, serotonin, acetylcholine and glutamate. The probe was fabricated on a polyimide substrate with 16 circular gold-film electrodes. These electrodes were modified with PEDOT/GluOx and PEDOT/ChOx for enzymatic detection of glutamate and acetylcholine, and with rGO/PEDOT/Nafion for the detection of dopamine and serotonin. Our electrochemical sensor achieved sensitivities of 184.21 and 219.29 μA/μM cm2 for glutamate and acetylcholine, respectively, with limits of detection (LOD) of 0.0242 and 0.0351 μM within a concentration range of 0.1–100 μM. For dopamine and serotonin, the sensor showed sensitivities of 195.9 and 181.2 μA/μM cm2, respectively, with LOD of 0.4743 and 0.3568 μM. This research advances the field of neurochemical sensing and provides valuable insights into the balance of neurotransmitters associated with neurological disorders. These insights improve diagnostic and therapeutic strategies. [ABSTRACT FROM AUTHOR]

Polymer dielectrics play an irreplaceable role in electrostatic capacitors in modern electrical systems, and have been intensively studied with their polarization and breakdown strength (Eb) optimized for high discharged energy density (Ud) at elevated temperatures. Small molecules have been explored as fillers, yet they deteriorate thermal stability of matrix which limits their optimal loading to ~1 wt%. Herein, we develop a polymer blend dielectric consisting of common polyimide and a bifunctional dipolar glass polymer which are synthesized from two small molecule components with wide band-gap and large dipole moment. The bifunctional dipolar glass with large molecular weight not only maintains thermal stability of polymer blends even at a high loading of 10 wt%, but also induces substantial enhancement in polarization and Eb than any of individual components does, achieving an ultrahigh Ud of 8.34 J cm−3 (150 °C) and 6.21 J cm−3 (200 °C) with a charge-discharge efficiency of 90%. The authors develop a polymer blend dielectric consisting of common polyimide and a bifunctional dipolar glass polymer which are synthesized through condensation polymerization of two small molecule components with wide band-gap and large dipole moment. [ABSTRACT FROM AUTHOR]

To improve the tribological properties of polar crane copper alloy bearings to withstand wear under dry sliding wear and grease lubrication at low temperatures, three kinds of coating materials modified by incorporating WS2 and SiC into polyamide‐imide/polyimide‐phenolic epoxy resin were designed. These composite coatings were sprayed on the surfaces of CuPb22.5Sn2.5 copper alloys by liquid spraying technique. Firstly, the tribological experiments were performed with three different coatings. Then, nanoindentation testing and wear morphology analysis were conducted. The results show that the hardness of the composite coatings decreases with the increase of WS2. As the content of WS2 increases, the coefficients of friction (CoFs) of coatings decreases under dry sliding wear. The S2 coating filled with 7.5 wt% WS2 exhibits the lowest wear rate and the best wear resistance under low temperature and dry sliding wear. The coatings form a lubricating film on the worn surface under dry sliding wear at −70°C, improving the wear resistance of the coatings. The primary wear mechanisms are adhesive wear and fatigue wear. The wear rates of the coatings increase with the increasing content of WS2 under low‐temperature grease lubrication. The S1 coating filled with 5.0 wt% WS2 exhibits the lowest wear. The S1 coating demonstrates a CoF of 0.07 and a wear rate of 6.5 × 10−6 mm3N−1 m−1 at 0°C, showing excellent friction‐reducing and wear‐resistant properties. The primary wear mechanism is adhesive wear. The wear mechanisms of polymer coatings are closely related to temperature. The dominant wear mechanisms transfer from abrasive wear to adhesive wear and fatigue wear under dry sliding wear and decreasing temperature. The wear mechanisms transfer from predominantly adhesive and abrasive wear to adhesive wear, fatigue wear, and abrasive wear under grease lubrication. The hardness of the coatings and the behavior of the polymer at various low temperatures are the primary factors that affect the differing wear mechanisms. [ABSTRACT FROM AUTHOR]

Optically transparent polyimide (PI) films with good atomic oxygen (AO) resistance have been paid extensive attention as thermal controls, optical substrates for solar cells or other components for low Earth orbit (LEO) space applications. However, for common PI films, it is usually quite difficult to achieve both high optical transparency and AO resistance and maintain the intrinsic thermal stability of the PI films at the same time. In the current work, we aimed to achieve the target by using the copolymerization methodology using the fluorinated dianhydride 9,9-bis(trifluoromethyl)xanthene-2,3,6,7-tetracarboxylic dianhydride (6FCDA), the fluorinated diamine 2,2-bis [4-(4-aminophenoxy)phenyl]hexafluoropropane (BDAF) and the polyhedral oligomeric silsesquioxane (POSS)-containing diamine N-[(heptaisobutyl-POSS)propyl]-3,5-diaminobenzamide (DABA-POSS) as the starting materials. The fluoro-containing monomers were used to endow the PI films with good optical and thermal properties, while the silicon-containing monomer was used to improve the AO resistance of the afforded PI films. Thus, the 6FCDA-based PI copolymers, including 6FCPI-1, 6FCPI-2 and 6FCPI-3, were prepared using a two-step chemical imidization procedure, respectively. For comparison, the analogous PIs, including 6FPI-1, 6FPI-2 and 6FPI-3, were correspondingly developed according to the same procedure except that 6FCDA was replaced by 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). Two referenced PI homopolymers were prepared from BDAF and 6FDA (PI-ref1) and 6FCDA (PI-ref2), respectively. The experimental results indicated that a good balance among thermal stability, optical transparency, and AO resistance was achieved by the 6FCDA-PI films. For example, the 6FCDA-PI films exhibited good thermal stability with glass transition temperatures (Tg) up to 297.3 °C, good optical transparency with an optical transmittance at a wavelength of 450 nm (T450) higher than 62% and good AO resistance with the erosion yield (Ey) as low as 1.7 × 10−25 cm3/atom at an AO irradiation fluence of 5.0 × 1020 atoms/cm2. The developed 6FCDA-PI films might find various applications in aerospace as solar sails, thermal control blankets, optical components and other functional materials. [ABSTRACT FROM AUTHOR]

Thermoplastic polyimides (TPIs) are promising lightweight materials for replacing metal components in aerospace, rocketry, and automotive industries. Key TPI attributes include low density, thermal stability, mechanical strength, inherent flame retardancy, and intrinsic fluorescence under UV light. The application of advanced manufacturing techniques, especially 3D printing, could significantly broaden the use of TPIs; however, challenges in melt-processing this class of polymer represent a barrier. This study explored the processability, 3D-printing and hence mechanical, and fluorescence properties of TPI coupons, demonstrating their suitability for advanced 3D-printing applications. Moreover, the study successfully 3D-printed a functional impeller for an overhead stirrer, effectively replacing its metallic counterpart. Defects were shown to be readily detectable under UV light. A thorough analysis of TPI processing examining its rheological, morphological, and thermal properties is presented. Extruded TPI filaments were 3D-printed into test coupons with different infill geometries to examine the effect of tool path on mechanical performance. The fluorescence properties of the 3D-printed TPI coupons were evaluated to highlight their potential to produce intricately shaped thermally stable, fluorescence-based sensors. [ABSTRACT FROM AUTHOR]

In the present study, the effect of varying titanium dioxide (TiO2) nanoparticles on the dielectric, thermal, and corrosion characteristics of PI-based composites prepared by spark plasma sintering was investigated. The results obtained revealed that the TiO2 nanoparticles were uniformly dispersed within the PI matrix. Addition of TiO2 into the neat PI markedly reduced its dielectric constant and electrical conductivity by 72.7% and 82.3%, respectively, as well as enhancing its breakdown strength by 16.7% at 8 wt% TiO2 loading. The nanocomposites depict better thermal stability and heat-resistance index characteristics when compared to the PI. Additionally, the produced nanocomposites exhibit improved corrosion resistance than that of the neat PI. The remarkable improvement in the dielectric, thermal stability, and corrosion resistance of the nanocomposites is achieved by better dispersion of the TiO2 particles in the polymer matrix. The enhancement in properties suggests TiO2/PI-based nanocomposites potential for a variety of applications in electrical insulation, thermal management, and harsh environment. [ABSTRACT FROM AUTHOR]

A novel phenylethynyl-terminated siloxane-containing ortho -hydroxy polyimide (O-SPI) was synthesized and physically blended with thermoplastic polyimide (PI) to enhance both the thermal and mechanical properties of polyimide, addressing the growing demand for high-performance materials in harsh environments. The blend underwent conversion to semi -Interpenetrating Polymer Networks (semi -IPNs) and benzoxazole structures through thermal curing of reactive phenylethynyl groups and thermal rearrangement of ortho-hydroxy imide units. The trends in thermal and mechanical properties were investigated in relation to the chemical structures and varying mass fraction of O-SPI. The covalent incorporation of semi -IPNs and rigid benzoxazole structures restrict segmental motion while the backbone linkage confers the toughness of the blends. These synergistic effects insure the cured blends with high glass transition temperatures (472.51°C) and tensile strength (117.81 MPa) simultaneously, demonstrating their potential for applications in challenging conditions. [ABSTRACT FROM AUTHOR]

Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace, defense, and opto-electronics, but polyimides are difficult to be reprocessed and recycled at the end of their service life, resulting in a significant waste of resources. Hence, it is of great significance to develop recyclable polyimides with comparable properties to the commercial products. Herein, we report a novel polymer-to-monomers chemically recyclable poly(imide-imine) (PtM-CR-PII) plastic, synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine bonds. The PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial polyimides. The PtM-CR-PII plastic possesses a high Young's modulus of ≈3.2 GPa and a tensile strength as high as ≈108 MPa, which also exhibits high thermal stability with a glass transition temperature of ≈220 °C. Moreover, the PtM-CR-PII plastic exhibits outstanding waterproofness, acid/alkali-resistance, and solvent-resistance, its appearance and mechanical properties can be well maintained after long-term soaking in water, highly concentrated acid and base, and various organic solvents. Furthermore, the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame retardancy. The PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index (LOI) value of 45.5%. Importantly, the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature, allowing easy separation and recovery of both monomers in high purity. The recovered pure monomers can be used to regenerate new PtM-CR-PII plastics, enabling sustainable polymer-monomers-polymer circulation. [ABSTRACT FROM AUTHOR]

This study investigates the synthesis and characterization of new diamines with carbazole and imidazole pendant groups, leading to the development of polyamides and polyimides. The polyamides were synthesized by reacting diamines with carboxylic acids using polyamidation and phosphorylation techniques, while polyimides were prepared by combining diamines and dianhydrides. FT–IR and 1H-NMR analyses were used for comprehensive structural elucidation of diamine, polyamides, and polyimides. The polyamides and polyimides with inherent viscosities ranging from 0.48 to 0.64 dL/g showed notable thermal stability. The T10% weight loss values were between 287 and 340 °C for polyamides and 321–381 °C for polyimides. The percentage of char residue varied between 33 and 56% at 700 °C. Additionally, the maximum emission wavelengths of polymers ranged from 410 to 436 nm. The presence of bulky carbazole and imidazole pendant groups facilitated the good solubility of the polymers in common organic solvents. The antibacterial properties of synthesized polyamides and polyimides against both Gram-negative and Gram-positive bacteria and fungi were investigated. [ABSTRACT FROM AUTHOR]

Composite materials with high heat dissipation and acceptable insulating properties are being developed. Minimizing filler contacts in the composite and is crucial for composite insulating materials. Here, an electrostatic adsorption method was used to prepare thermoplastic polyimide (tpPI) / orientation micro‐sized hexagonal boron nitride (h‐BN) composite insulating materials. Then the effects of h‐BN particle size on the thermal conductivity and DC breakdown strength were investigated. Additionally, the finite element method was used for heat conduction analysis and the results were compared to the measurements. The particle size of the h‐BN significantly influences the dc breakdown strength and the thermal conductivity. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

New foaming prepolymer compositions based on 4,4′‐oxydiphthalic anhydride, 4,4′‐diaminodiphenyl ether, 1,6‐hexamethylenediamine (HMDA), and a surfactant were synthesized. Polyimide (PI) foams containing from 0 to 40 mol% HMDA were prepared. The possibility of controlling the pore sizes in a foam material by selecting different fractions (250–400 μm) of particles of the powdered foam composition for heat treatment was shown. Scanning electron microscopy studies of morphology of the synthesized PI foams (PIFs) showed that all foams exhibited open cellular structures with pore diameters ranging from 50 to 500 μm. The influence of the components of the foaming composition (surfactant and aliphatic diamine) on the structure, thermal, and mechanical properties of the resulting PIFs was traced. The samples of PIFs containing 20% and 30% HMDA were elastic (the corresponding stress–strain curves were almost linear up to the 30% deformation) and able to restore their shape after removing the load. The resulting foams exhibited high thermal stability (the onset of weight loss was observed in the 470–500°C range). It was revealed that the synthesized PIF compositions were incombustible in an open flame. Due to their high heat resistance and nonflammability, the obtained PIFs can be used for thermal insulation applications in the aerospace, transport, construction, and microelectronics industries. Highlights: New, lightweight, flexible, and nonflammable PIFs have been synthesized.The HMDA additive imparts elasticity to PIFs.The introduction of a surfactant (KT‐6) makes the PIF homogeneous. [ABSTRACT FROM AUTHOR]

AbstractNanodiamonds are unique spherical carbon nano-entities having the advantages of very high surface area and high optical, thermal, wear and strength characteristics. Like other carbonaceous nanoparticles (like fullerene, graphene or carbon nanotube), nanodiamond nano-reinforcements have been investigated for the significant types of polymeric matrices (such as thermosets, thermoplastics, rubbers) nanocomposites. Consequently, this overview was planned to systematically describe the current scientific status of the nanodiamonds reinforced thermoplastic nanomaterials. In this regard, polyamide/nanodiamonds, polyimide/nanodiamonds and polystyrene/nanodiamonds nanocomposites have been fabricated using the facile solution, in-situ and melt mixing techniques. We suggest that including nanodiamonds in polyamides and polyimides increased their engineering characteristics, like mechanical properties and thermal stability, of the resulting nanocomposites due to a distinct interface formation and their compatibilization effects toward these matrices. Correspondingly, including nanodiamonds in polystyrene has been observed to increase the intrinsically low strength/toughness features of this polymer. Predominantly, nano-reinforcement and miscibility effects of the nanodiamonds with the polystyrene and their mutual matrix-nanofiller synergies were responsible to improve the overall microstructural and physical properties of the resulting nanocomposites. As per our analysis, the research reports so far on the important categories of the nanodiamonds reinforced thermoplastic matrix nanocomposites have shown important technical applications in the fields of high-tech coatings, membranes and energy devices. [ABSTRACT FROM AUTHOR]

Hard carbon, characterized by high ion storage capacity, low operating voltage, and excellent cycling stability, is considered an ideal negative electrode material for sodium‐ion batteries. However, the high cost and low carbon yield of thermosetting precursors limit their practical application in SIBs, while low‐cost and high‐yield raw materials exhibit highly ordered carbon structures and narrow interlayer spacing under high‐temperature carbonization. Discarded polyimide materials are inexpensive, which offer a high carbon yield and possess good thermal stability and thermoplasticity, with functional groups of imide rings (−CO−N−CO−) on their main chains. This study recycled and converted polyimide materials into hard carbon materials from discarded engineering plastics, investigating the influence of carbonization temperature on the degree of graphitization, interlayer spacing, and pore structure of the materials to achieve high reversible sodium storage capacity. After carbonization at 1300 °C, the polyimide material exhibited 319 mAh g−1 reversible capacity and excellent electrochemical performance (with a capacity retention of 91.92 % after 100 cycles at a 0.5 C current rate) and rate performance (up to 242.5 mAh g−1 at 2 C). This study provided a simple, high‐yield, and effective method for the reuse of discarded organic polymers, promoting the sustainable utilization of resources. [ABSTRACT FROM AUTHOR]

The growing demand for electronic devices has induced a significant requirement for high energy density capacitors. In this investigation, we introduced small groups of cyanoethyl cellulose (CEC) into a polyimide (PI) substrate to create all organic CEC/PI composite films for high energy density capacitor applications. Due to the large dipole moment in C–CN dipoles in CEC groups, the dielectric constant of the CEC/PI-5 (5% CEC) composite increased by 26.3% to 4.31. Compared to the pristine PI film at room temperature, the breakdown field of the CEC/PI-0.5 increased by 4.7% from 502.29 to 526.1 MV m−1 and the energy storage density increased by 95% to 11.70 J cm−3. Furthermore, the CEC/PI-0.5 film exhibited an energy density of 6.39 J cm−3 with the breakdown field of 400 MV m−1 at 150 °C, which is 93.05% higher in energy densities than that of the pristine PI film. Furthermore, simulation results indicate that CEC groups can introduce deep traps in the CEC/PI composite, which can inhibit charge movement in the composite and increase the breakdown field of it. In this study, it was found that by adding small amount of CEC polar group in PI film, the high temperature energy density of CEC/PI composite materials was significantly improved. This study not only makes a significant contribution to the development of high-temperature energy-density capacitors, but also pave a way by using small molecule polar polymers to improve the energy density of dielectric materials at high temperature. [ABSTRACT FROM AUTHOR]

To improve the thermodynamic and mechanical properties of asymmetric polyimide (PI), a method to enhance the linearity of PI by using a structural reorganization approach was designed. First, two novel diamines containing benzimidazole and benzoxazole groups, namely PADBZ and PDBOA, were constructed and synthesized. Thereafter, two new kinds of PI films (PADBZ‐PMDA and PDBOA‐PMDA) were prepared and polymerized with 1,2,4,5‐benzenetetracarboxylic anhydride (PMDA). Based on structural reorganization, PADBZ‐PMDA and PDBOA‐PMDA had repeating units of the same chemical composition and different linearity with PABZ‐BPDA and BOA‐BPDA, respectively. Comparing PADBZ‐PMDA and PABZ‐BPDA, due to the transfer in the position of benzene, PADBZ‐PMDA with high linearity showed the improved heat resistance (Tg up to 448°C), dimensional stability (CTE down to 2.3 ppm/K) and mechanical properties. PDBOA‐PMDA and BOA‐BPDA had the same situation. This study provided a unique solution to enhance the performances of PI by increasing the linearity using a structural reorganization approach. [ABSTRACT FROM AUTHOR]

Traditional polyimides have highly conjugated structures, causing significant coloration under visible light. Fluorinated colorless polyimides, known for their light weight and excellent optical properties, are considered ideal for future aerospace optical lenses. However, their lifespan in low Earth orbit is severely limited by high-density atomic oxygen (AO) erosion, and the degradation behavior of fluorinated polyimides under AO exposure is not well understood. This study uses reactive molecular dynamics simulations to model two fluorinated polyimides, PMDA-TFMB and 6FDA-TFMB, with different fluorine contents, to explore their degradation mechanisms under varying AO concentrations. The results indicate that 6FDA-TFMB has slightly better resistance to erosion than PMDA-TFMB, mainly due to the enhanced chemical stability from its -CF3 groups. As AO concentration increases, widespread degradation of the polyimides occurs, with AO-induced cleavage and temperature-driven pyrolysis happening simultaneously, producing CO and OH as the main degradation products. This study uncovers the molecular-level degradation mechanisms of fluorinated polyimides, offering new insights for the design of AO erosion protection systems. [ABSTRACT FROM AUTHOR]

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman–Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam. [ABSTRACT FROM AUTHOR]

In this study, vinyltriethoxysilane (TEVS) was introduced onto the surface of carbon fiber using liquid-phase oxidation and impregnation methods to incorporate vinyl groups onto the carbon fiber, thereby enhancing the chemical bonding between the carbon fiber and norbornene–polyimide (PI-NA). Through a systematic study of the hydrolysis conditions and concentration of the TEVS solution, the optimal modification conditions were determined. These conditions were used to graft TEVS onto the surface of oxidized carbon fiber to prepare carbon-fiber-reinforced PI-NA composites (CF/PI-NA). The results show that when carbon fiber was treated with a 0.4 wt% TEVS solution, the interlaminar shear strength (ILSS) of the composites reached 65.12 MPa, and the interfacial shear strength (IFSS) reached 88.58 MPa, representing increases of 27.58% and 35.62%, respectively, compared to the CF/PI-NA composite materials prepared from untreated carbon fiber. It is worth noting that the modification method described in the study is simple and easy to implement, and it has the potential for large-scale continuous production applications. [ABSTRACT FROM AUTHOR]

Ammonia is one of the most common toxic gases in livestock and poultry environment. Its high concentrations can pose a potential health threat to humans, plants, and animals. Traditional active detection methods increase energy consumption, heat buildup may affect detection system performance, and are not suitable for livestock and poultry environment where circuit wired connections are limited. With the gradual transition from traditional to smart agriculture, radio frequency identification (RFID) technology has been widely used to integrate device sensing and wireless communication, due to its lightweight, low-cost, and non-line-of-sight readability. In this study, a passive RFID sensor simulation model was designed by using the high-frequency structure simulator (HFSS) software. A split-ring resonator was employed to operate at a center frequency, which was adjusted according to the length of the open gap. The additional flexibility was provided rather than the closed-loop resonant structure. According to the HFSS simulation model, a physical RFID tags were fabricated by screenprinting technique based on polyethylene terephthalate and polyimide substrates, and carbon nanotubes with high surface area were selected as ammonia-sensitive materials. The surface morphology and nanostructure of carbon nanotube materials were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor resistance was measured due to the contact of ammonia molecules on the surface of the sensitive materials, mathematical model of passive detection was established to analyze the sensing mechanism. Once an ammonia molecule came into contact with the surface of a carbon nanotube, some electrons or holes were used to change the carrier concentration, thus leading to the varying resistance of the carbon nanotube. Antenna frequency or impedance mismatch was found during adsorption between ammonia and free carriers on the surface of carbon nanotubes, thereby affecting the backscattering signal domain of RFID, the detection process of RFID sensing tags was simulated by analyzing the variation of transmission coefficients. Furthermore, a radio-frequency test system for ammonia testing in laboratories and livestock environment was built. The transmission gain of the tag can be calculated by detecting the transmission coefficient offset and amplitude change. According to the tag power reflection coefficient, return loss and phase analysis, the resonant frequency of the tags varied by 270 MHz under 0-18 mg/L ammonia ambient. The detection efficiency of the tag was easily affected by carbon dioxide, temperature and humidity factors, due to manual cutting, substrate deformation, environmental interference and other factors. There was a deviation about 0.05 GHz between the resonance frequency of the physical tag and the simulated resonance frequency, the sensing tag's sensitivity was about 15 MHz·L/mg, and the maximum reading distance was 24 cm. The sensing tag has obvious advantages in terms of service life and response time compared to commercial ammonia sensors. The tag sensor can be expected to fully meet the passive detection needs of ammonia. This finding can provide a reliable theoretical and practical basis for the passive detection of ammonia from agricultural sources. Further research can also be conducted to select the sensitive materials or suppress the interferences of radio frequency links in the future. [ABSTRACT FROM AUTHOR]

Highlights Novel water‐soluble polymer‐based sizing agents for carbon fiber/poly(aryl ether ketone) composites (CF/PAEK) have gained attention. However, a challenge remains: the sized CF bundles lack flexibility, and the effect of this on the properties of the composite has not been discussed. Herein, a water‐soluble polyimide oligomer (OL) sizing agent was developed, and the sizing effect was comprehensively evaluated. The conventional molecular weight polyimide (HP) sizing agent was also assessed for comparison. Although the interfacial shear strength of the sized CF monofilaments is enhanced due to improved surface roughness and wettability, the effect of the OL sizing agent on the composite's interlaminar shear strength (ILSS) and tow's flexibility differed from that of the HP sizing agent. Compared with HP‐CF, the yarn spreading rate of OL‐CF tow is increased by about eight times, and the ILSS of OL‐CF/PAEK composites with 2 and 5 MPa molding pressure is increased by 69% and 222%, respectively. The HP sizing agent weakens the tow's flexibility and yarn spreading ability, which is not conducive to the resin penetration in the tow, resulting in lower ILSS. In contrast, the OL sizing agent considers the tow's flexibility and composite's interlaminar property, showing great application potential. Two PI‐based sizing agents with diverse film‐forming capacities were prepared. The ILSS of CF/PAEK with OL sizing agent was significantly improved. HP sizing agent weakened the tow flexibility and interlaminar property. The interaction of sizing layer—resin penetration—ILSS was proposed. [ABSTRACT FROM AUTHOR]

Ladder-like structured poly(phenyl-co-glycidoxypropyl) silsesquioxanes with different ratios of phenyl to glycidyl group (LPS64 and LPS 82) were synthesized using simple hydrolysis reaction followed by condensation polymerization of phenyltrimethoxysilane (PTMS) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS). Two series of hybrid polyimide composites (PI/LPS64 and PI/LPS82) with different contents of LPS (10, 20, and 30 wt%) were prepared by the chemical reaction of epoxy groups in LPS64 or LPS82 and the terminal amine groups in poly(amic acid). The dielectric constant (k) of hybrid PI composites (k = 1.3) was lower than that of pure polyimide (k = 2.9) and the degree of roughness was increased according to the increase of LPS contents. The dispersion of LPS in the PI matrix was improved due to the chemical bonding between LPS and PI. The thermal stability of PI/LPS82 was higher than that of PI/LPS64 due to the enhanced π-π stacking between PI matrix and LPS82 with more phenyl groups as compared to LPS64. [ABSTRACT FROM AUTHOR]

Two novel diamines 1‐(4‐aminophenyl)‐1,3,3‐trimethyl‐2,3‐dihydro‐1H‐indene‐5‐amine and 4‐amino‐N‐(4‐(5‐(4‐aminobenzamide)‐1,3,3‐trimethyl‐2,3‐dihydro‐1H‐inden‐1‐yl) phenyl) benzamide containing indene and amide groups were successfully designed and synthesized, and a series of colorless polyimides (CPIs) derived from the two diamines with 1,2,4,5‐cyclohexanetetracarboxylic dianhydride in various ratios were copolymerized. The introduction of aliphatic ring structures was conducive to the improvement of optical properties, while the incorporation of amide groups improved thermal and mechanical properties. These CPI films exhibited excellent optical properties (T400 > 80%), high heat resistance (Tg > 300 °C) and mechanical properties with the synergistic action of the two groups. Furthermore, the effect of the content of amide groups on the intermolecular interaction of CPIs was systematically analyzed. This study provides a fancy method for the development of heat‐resistant colorless materials for optical applications. [ABSTRACT FROM AUTHOR]

A fluorescein‐based diamine, 2‐(3,6‐bis(4‐amino‐3‐hydroxyphenoxy)‐9H‐xanthen‐9‐yl) benzoic acid (CADA), was synthesized and copolymerized with Durene and 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to form a 6FDA‐Durene/CADA (3:2) copolyimide. The copolyimide was thermally cross‐linked at 300–425°C to form a series of decarboxylated cross‐linked polyimides. Compared with the 6FDA‐CADA polyimide, the incorporation of Durene diamine increased gas permeability of the pristine and the thermally cross‐linked polyimides greatly. The copolyimide cross‐linked at 375°C showed separation performance to the O2/N2 gas pair beyond the 1991 Robeson upper limit, while the CO2/CH4 separation property of the copolyimide cross‐linked at 425°C (PI‐425) was close to the 2008 Robeson upper limit. Moreover, the anti‐CO2‐induced plasticization property of the 6FDA‐Durene/CADA(3:2) copolyimides was improved by cross‐linking. The copolyimides cross‐linked at 350°C and above were not plasticized at a CO2 pressure up to 30 atm. This study showed that gas transport property of the decarboxylated cross‐linked polyimides could be improved significantly by the incorporation of bulky diamino moiety. The fluorescein‐based copolyimide had great potentials for gas separation applications. [ABSTRACT FROM AUTHOR]

A series of new thermosetting diimides containing terminal propargyl groups was synthesized via one-step high-temperature catalytic condensation of dianhydrides of a tetracarboxylic acid with N-Boc-(4-propargyloxy)aniline (APR) in the so-called "active medium", viz. molten benzoic acid. Structures of the obtained compounds were confirmed by 1H NMR and IR spectroscopy. The effect of symmetrical and unsymmetrical structures of the middle bis-imide moiety obtained from dianhydrides of isomeric diphenyltetracarboxylic acid on physicochemical characteristics of the diimides was evaluated. A similar comparison of properties was also carried out for a pair of new propargyl-containing diimides synthesized from dianhydrides of symmetric and asymmetric structure: 4,4-biphenylenedioxydiphthalic and 3,4-biphenylenedioxydiphthalic dianhydrides, respectively. Thermal properties of thermosetting oligoimides were estimated using DSC and TMA methods. It was found that their thermal properties and solubility in organic solvents depend significantly on the structure of central bis-imide moiety. [ABSTRACT FROM AUTHOR]

A series of new oligoimides based on 4,4- and 3,4-oxydianiline and 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, possessing different average chain lengths, and containing terminal propargyl groups were synthesized according to an efficient single-step high-temperature polycyclocondensation method. Their molecular weight characteristics, solubility in organic solvents, thermal (DSC, TMA, and TGA), and rheological properties were studied. The synthesized oligoimides exhibited a significantly lower exothermic effect upon curing due to their elongated chain as compared to diimides. The oligoimides upon increasing the temperature enter into a viscous fluid state, in which they remain up to the curing onset temperature of 270–320 °C. The symmetry of structure of the diamine moiety (4,4-ODA or 3,4-ODA) and the molecular weight of oligoimides affect the temperature of transition to the viscous fluid state. [ABSTRACT FROM AUTHOR]

Advancements in flexible electronic technology, especially the progress in foldable displays and under‐display cameras (UDC), have created an urgent demand for high‐performance colorless polyimide (CPI). However, current CPIs lack sufficient heat resistance for substrate applications. In this work, four kinds of rigid spirobifluorene diamines are designed, and the corresponding polyimides are prepared by their condensation with 5,5′‐(perfluoropropane‐2,2‐diyl) bis(isobenzofuran‐1,3‐dione) (6FDA) or 9,9‐bis(3,4‐dicarboxyphenyl) fluorene dianhydride (BPAF). The rigid and conjugated spirobifluorene units endow the polyimides with higher glass transition temperature (Tg) ranging from 356 to 468 °C. Their optical properties are regulated by small side groups and spirobifluorene structure with a periodically twisted molecular conformation. Consequently, a series of CPIs with an average transmittance ranging from 75% to 88% and a yellowness index (YI) as low as 2.48 are obtained. Among these, 27SPFTFA‐BPAF presents excellent comprehensive performance, with a Tg of 422 °C, a 5 wt.% loss temperature (Td5) of 562 °C, a YI of 3.53, and a tensile strength (δmax) of 140 MPa, respectively. The mechanism underlying the structure‐property relationship is investigated by experimental comparison and theoretical calculation, and the proposed method provides a pathway for designing highly rigid conjugated CPIs with excellent thermal stability and transparency for photoelectric engineering. [ABSTRACT FROM AUTHOR]

Composition and morphology of two types of bilayers of plasma‐enhanced chemical vapor deposition hydrogened silicon nitride (SiNx:H) and polyimide (PI), as effcient barrier against moisture in SiC‐based power devices, are investigated. Two types of silicon nitrides are obtained by changing the flow ratios of the SiH4 and NH3 precursors. Rutherford Backscatterered analyses show that the Si/N ratio varies from 0.6 to 0.8. Elastic recoil detection analyses show that the sample with higher nitrogen content has a higher total bound hydrogen content of 7.8 × 1017 cm−2 with respect to the 7.1 × 1017 cm−2. Fourier‐transform infrared spectroscopy characterizations show Si–H group concentrations of 0.96 × 1017 and 6.86 × 1017 cm−2 and NH groups of 4.82 × 1017 and 2.28 × 1017 cm−2, respectively. Silicon nitride films with higher concentration of N–H groups show higher reactivity and permeability to water, making them less effective as a barrier layer. Atomic force microscopy analyses of a PI layer deposited on the nitride layer, SiNx:H/PI show for both type of samples a similar roughness, indicating planarization that can increase the adhesion of SiNx:H/PI and resistance to moisture. The delamination mechanism of the bilayer under pressure pot test conditions is proposed. [ABSTRACT FROM AUTHOR]

To enhance the performance of polyimides, novel polyimides (P1, P2, P3) were synthesized through the reaction of isophthalic dianhydride with a series of furan-based diamines. The structures and properties of these polyimides (P1, P2, P3) were analyzed through molecular dynamics and quantum chemical simulation methods, including glass transition temperature, dielectric properties, free volume, and cohesive energy density. Compared with traditional polyimides, the results showed that P1, P2, and P3 exhibited a significant increase in glass transition temperature and cohesive energy density, while their dielectric properties decreased compared to traditional PI (3.4–3.6), all falling within the range of (2.5-3.0). The free volume also decreased. However, there was no significant impact on the materials' radial distribution functions at the atomic level. [ABSTRACT FROM AUTHOR]

This study reports a micromachined parylene-C-coated integrated electrode (IDE) sensor fabricated on a polyimide film. Glucose and uric acid within the human sweat concentration range were tested using hydrothermally grown ZnO nanoparticles (NPs) immobilized on the IDE regions of sensors and modified with urate oxidase and glucose oxidase enzymes. Four important sensing parameters, including capacitance, impedance, resistance, and phase, were simultaneously investigated during the dynamic test. The sensor fabrication and characterization of ZnO NPs and ZnO NP formed sensing film were described in detail. The experimental results show that the amount of capacitance change and phase change vs. the concentration variation of glucose and uric acid exhibits an excellent linear regression relationship. On the other hand, the amount of impedance change vs. concentration variation of glucose and uric acid exhibits a power regression relationship. Sensitivities of uric acid and glucose detection based on capacitance changes were 0.1131 pF/µM and 0.7875 pF/µM, respectively. Limits of detection of uric acid and glucose were 1.23 µM and 0.311 µM, respectively. Thus, the developed sensor can be applied to wearable devices for the quantitative analysis of sweat composition in the future. [ABSTRACT FROM AUTHOR]

As triboelectric nanogenerator (TENG) technology continue to evolve, its application in harsh environments has increasingly captivated the interest of researchers. However, the current research on heat-resistant triboelectric materials remains predominantly focused on the development of tribo-negative materials, with scant attention given to their equally crucial tribo-positive counterparts. In this study, the tribo-positive polyimide (PI) material with enhanced tribo-positivity is developed by integrating amide groups with electron-donating effects into the molecular chain. Furthermore, the TENG devices based on this series of tribo-positive PI materials have demonstrated an open-circuit voltage (VOC) of 242 V, a short-circuit current (ISC) of 8.13 μA, and a transferred charge (QSC) of 117 nC. Notably, these devices also demonstrate the capability to efficiently generate electricity even under elevated temperature conditions. This work not only proposes a potential molecular design strategy for developing high-performance tribo-positive PI materials applicable in TENGs, but also markedly propels the advancement of robust energy-harvesting devices engineered for operation at elevated temperatures. [ABSTRACT FROM AUTHOR]

Advanced flexible display materials have drastically sparked considerable interest for heat‐resistant, low dielectric, and transparent polyimide (PI) materials. In light of this, our study aims to develop high‐performance semi‐aromatic PI films, followed by investigate the correlations between bridged‐alkyl/heteroaromatic ring structures and their thermal, dielectric, optical, and mechanical properties. Such PI films, namely AP‐PIs, were synthesized with a one‐step high‐temperature method between 4‐[4‐(4‐aminophenoxy) phenyl]‐2‐(4‐aminophenyl)‐1(2H)‐phthalazinone (DHPZDA) and various commercial alicyclic dianhydrides. The incorporation of rigid phthalazinone structures significantly enhanced thermal resistance and mechanical flexibility, while simultaneously reducing their dielectric constant (Dk), attributed to the large polymer internal free volume. Impressively, the prepared films exhibit exceptional glass transition temperature (Tg) as high as 419°C (DMTA tanδ peak), low Dk as low as 2.71, and elongation at break (ε %) up to 50.4%. Furthermore, AP‐PI films demonstrate reasonable solubility and optical transparency within the UV–visible region. The maximum optical transmittance at 550 nm (T550 nm) could reach 83.01%. These desirable properties position these materials as promising candidates for flexible substrate applications. [ABSTRACT FROM AUTHOR]

Modern society relies heavily on producing commercial and industrial plastics to improve the quality and quantity of our lives. However, increased fire risks threaten commercial operations and the potential impact of high‐performance electronic and transportation technologies that utilize polymeric materials. Despite significant monitoring and reduction of commonly used halogenated flame retardants, their worldwide usage still poses environmental hazards. Many non‐halogenated flame‐retardant compounds are viable additives for synthetic polymers; however, their incorporation often results in reduced composite homogeneity and mechanical strength. This review focuses on reactive flame retardants and the effect of polymer structure on inherent flame retardance in recent studies. The synthesis and characterization of polymeric systems (e.g. polyurethanes, polyamides, polyimides, polyesters and epoxy resins) are discussed in terms of structure–flame‐retardant performance using a complement of analytical tools, including thermogravimetric analysis, cone calorimetry, limiting oxygen index and UL 94 testing. These commercially important polymeric systems represent a broad compositional space for future adaptation and the discovery of increasingly modular polymeric materials with, while also contributing to the fundamental understanding of unique combinations of gas‐ and condensed‐phase mechanisms of flame retardance. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study examined the effects of silane-modified polyimide polymer (PIS) on cement mortar. The PIS was added to replace cement in a specified ratio. Obtained results revealed that the PIS caused retardation on setting time, and accelerated UPV mostly by encapsulating unhydrated cement particles, filling pores, or reacting with C–S–H and Ca(OH)2 with shifting to Si–O vibrations. SEM results showed a good compact interface without forming considerable agglomeration and voids on the microstructure, and this improved flexural and compressive strength properties. In conclusion, silane-modified polyimide as an admixture or cement replacement can be recommended for construction industries to enhance the properties of cement mortar. [ABSTRACT FROM AUTHOR]

Polyimides are used in various applications, including fuel cells, membranes, and microelectronics, due to their outstanding tensile properties, great thermal stability, low dielectric constant, and chemical inertness. Applications requiring even lower dielectric constants include interlayer dielectrics and tape‐automated bonding. In this study, a covalent organic framework (COF‐1) was synthesized and dispersed in various percentages into a solution of terpoly(amide acid) (TPAA) to produce COF‐1/terpolyimide composites. 3,3′,4,4′‐Oxydiphthalic dianhydride (ODPA), 3,3′,4,4′‐biphenyltetracarboxylicdianhydride (BPDA), and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were reacted with 4,4′‐(hexafluoroisopropylidene)bis[(4‐aminophenoxy)benzene] (HFBAPP) or 4,4′‐(hexafluoroisopropylidene) dianiline (6FpDA) to form terpoly(amide acid). In this case, monomers with fluorinated substituents (HFBAPP, 6FpDA, and 6FDA) were utilized to improve free volume. Pores of COF‐1 and gaps between polyimide chains and COF‐1 can be filled with air with a dielectric constant (κ) ~1, lowering the κ value of terpolyimide composites. The κ value of COF‐1/terpolyimide composites decreased as COF‐1 content increased, reaching a minimum of 1.96. Tensile properties decreased slightly with increasing COF‐1 levels. The terpolyimides and their composites were thermally stable up to approximately 520°C. As a result, these polymer composites look promising for use as insulators in microelectronic applications. Highlights: Terpolyimide is prepared using fluorinated monomers to improve bulk volume.Incorporated COF‐1 into terpoly(amide acid) to introduce pores/voids and reduce dielectric constant.Developed COF‐1/terpolyimide composites with a low dielectric constant of 1.96.Optimized COF‐1/terpolyimide composites for microelectronic applications. [ABSTRACT FROM AUTHOR]

High temperature (200-260°C) military composite engine components made of carbon fiber thermoset materials are susceptible to erosion damage. Evidenced by wear seen during operation, erosion protection remains a challenge for composites in the engine air flow path. In this paper, we investigate polyetheretherketone (PEEK), thermoplastic polyimide (TPI), and ceramic fabric (Nextel™) as potential high temperature erosion coatings for thermoset polyimide composite engine components. We evaluate the erosion protection materials for two qualities: (1) co-moldability with thermoset polyimide composite panels, and (2) erosion resistance to a sandblasting test. Autoclave and compression molding were used to test co-moldability with different manufacturing methods. The compression molding process was optimized to reduce surface defects using a pre-imidization step before the erosion protection layer was applied and final cure was completed. Comolded test panels were cut into small coupons for sandblasting. After 60 s of alumina sandblasting PEEK had negligible mass loss, whereas the TPI and ceramic fabric had roughly the same erosion rate as the uncoated polyimide laminate. [ABSTRACT FROM AUTHOR]

Aluminum‐doped ZnO (AZO) were successfully prepared on polyimide (PI) film using electrochemical deposition. Field emission scanning electron microscopy (FESEM) analysis revealed that as the aluminum concentration increased, the morphology of AZO nanostructures changed from pellets to nanorods. X‐ray photoelectron spectrometry (XPS) was employed to study the chemical states of undoped and Al‐doped ZnO on a polyimide substrate. The X‐ray diffraction (XRD) patterns of the PI/AZO nanostructures showed a polycrystalline wurtzite structure with a crystallographic orientation along the (002) plane. The XRD analysis also indicated that the average crystallite size decreased from 50.5 nm to 31.0 nm with increasing aluminum concentration (from 0.05 mM to 10 mM). Transmittance analysis revealed that with increasing aluminum concentration, the average optical transmittance in the visible region decreased from 90 % to 75 %. The aluminum concentration has a significant effect on the electrical properties of the samples, as shown by current‐voltage (I–V) and Hall measurements. Among the samples, the AZO/PI film prepared with 5 mM aluminum concentration exhibited the minimum electrical resistivity (4.14×10−2 Ω.cm), the highest carrier density (1.10×1021 cm−3) and the Hall mobility (5.40 cm2 V−1 s−1). We also discuss the possible mechanisms underlying these results compared to undoped ZnO films. This study contributes to the potential applications in flexible electronics and optoelectronics by demonstrating the tunability of AZO nanostructures on a flexible polyimide substrate through controlled aluminum doping. [ABSTRACT FROM AUTHOR]

The continuous upgrading of electronic technology has facilitated the integration and miniaturization of electronic and electrical equipment, as well as putting great pressure on the multifunctional demand for internal materials. Developing insulating materials with both low permittivity and high thermal conductivity has become imperative. This perspective focuses on polyimide (PI), which is the top material of the polymer material pyramid, discusses the characteristic parameters that affect its dielectric property and thermal conductivity. A series of basic schemes to regulate the dielectric/thermal properties of PI are summarized, revealing the bottlenecks and drawbacks of the current research. Future development trends of PIs featured low permittivity-high thermal conductivity are anticipated, and novel ideas are proposed for the development of new generation of multifunctional PIs. [ABSTRACT FROM AUTHOR]

The intricate interplay between chemical composition and the incorporation of functional fillers plays a pivotal role in shaping the structural attributes and separation efficacy of mixed matrix ultrafiltration membranes. In this work, we report the utilization of a novel organic filler of hydrophilic modified polyimide particles (PI‐SO3) for the first time in the preparation of mixed matrix ultrafiltration membranes. A series of ultrafiltration membranes were fabricated using polysulfone as the matrix material and PI‐SO3 as the additive. The addition of PI‐SO3 to the mixed matrix membrane effectively enhanced both water flux and antifouling ability. The ultrafiltration membrane with 0.2% particle content exhibited the highest pure water flux at 535.5 L h−1 m−2, owing to the synergistic regulation of pore structures and surface hydrophilicity. The ultrafiltration membrane with 0.5% PI‐SO3 particles demonstrated the highest flux recovery rate at 76.8%, attributed to the superior hydrophilicity displayed by the added particles within the ultrafiltration membrane. The increased particles content correlated with improved hydrophilicity on the membrane surface, resulting in enhanced antifouling performance. The hydrophilic modified particles effectively regulated pore structures, surface hydrophilicity, and surface charge, ultimately enhancing the performance of mixed matrix ultrafiltration membranes for wastewater purification. Therefore, the use of modified polyimide particles as fillers introduces an innovative method to economically enhance ultrafiltration membranes, providing a potential solution to mitigate the economic costs associated with trade‐off effects during the modification process. [ABSTRACT FROM AUTHOR]

Gallium ions have a special action mechanism that interferes bacterial iron metabolism, thereby possessing great potential for the treatment of bacterial infections. In this work, gallium ions‐cross‐linked konjac glucomannan/polyacrylamide (KGM/PAM/Ga3+) hydrogels are successfully constructed with satisfactory swelling ability, appropriate mechanical properties and adjustable degradation performance. Ga ions as a kind of cross‐linking agent can enhance the stability, and more importantly, improve the bactericidal ability of hydrogel, thus forming novel functional KGM/PAM/Ga3+ hydrogels for treating wounds. After the evaluation of antibacterial activity and biocompatibility, KGM/PAM/Ga3+ hydrogels can effectively inhibit the proliferation of bacteria through the gradual and sustainable release of Ga ions from the hydrogel with negligible cytotoxicity and good blood compatibility. Furthermore, they possess exceptional self‐healing behavior, and can be readily adapted to varying degrees of bending, which matches skin wound dressing application. Finally, the results of wound healing performance and histological evaluation demonstrate that KGM/PAM/Ga3+ hydrogels can efficiently accelerate infected wound healing and facilitate the regeneration of skin tissues. [ABSTRACT FROM AUTHOR]