Inspired by nature's sophisticated architectures, lightweight and robust nanofiber-assembled aerogels have emerged as promising platforms for advanced wearable electronics. Despite growing demand driven by artificial intelligence and internet of things technologies, flexible piezoresistive sensors still face challenges in balancing sensitivity and detection range, while maintaining cyclic stability and environmental adaptability. To overcome these limitations, a "layer-porous-layer" homologous hybrid dimensional network structured polyimide nano-fiber (PINF)/carbon nanotube (CNT) composite aerogel was fabricated through an integrated process of electrospinning, directional freeze-drying, and thermal imidization. By selectively dissolving polyamic acid nanofibers (PAANF) with triethylamine (TEA) to generate homologous PAAS oligomers as crosslinkers, a "skeleton-binder" homologous hybrid dimensional network was constructed. Meanwhile, directional freezing was used to induce the orientation of solid components, combined with thermal imidization covalent cross-linking, to achieve the synergistic construction of hierarchical porous and conductive networks. Benefiting from the homologous hybrid dimensional network, the resulting composite aerogel demonstrated an ultra-low density (25 mg/cm3), excellent compressive cyclic stability (no significant performance degradation over 6000 cycles), high sensitivity (S = 21.77 kPa-1), and a wide detection range (0-80% strain/0-70 kPa stress). It also exhibited fast response/recovery times (100ms and 60 ms, respectively) and outstanding long-term sensing reliability with no significant performance degradation over 6000 cycles. The integrated thermal insulation and flame-retardant characteristics further enhanced its suitability for extreme environment applications. These comprehensive performances not only verified the practical value of PINF/CNT composite aerogels in wearable electronics, human motion monitoring and extreme environment sensing applications, but also established a new technical path and material strategy for designing high-performance flexible pressure sensors.

Incorporating functional groups capable of interacting with gas molecules into the molecular structure is a pivotal strategy for enhancing the performance of polymer-based gas separation membranes. In this study, two diamines featuring spiro-bis-indane moieties and distinct functional groups were separately polymerized with 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to synthesize two polyimide membranes. The effects of hydroxyl (-OH) groups and phenylamino (-NHPh) groups on gas separation performance were systematically investigated. Hydroxyl groups are known to enhance CO2 solubility via hydrogen-bond-like interactions while disrupting chain packing to increase free volume, synergistically improving separation efficiency. This work further demonstrates that the basic phenylamino groups selectively adsorb CO2 through Lewis acid-base interactions, boosting CO2 solubility and amplifying solubility differences with nonpolar gases. Additionally, the rigid spiro-bis-indane structure collaborates with these functional groups to tailor the microporous network, thereby optimizing gas transport properties.

To achieve high-performance colorless polyimide (CPI) films, this study employed a molecular structure design strategy aimed at suppressing the charge transfer complex (CTC) effect between molecular chains by introducing twisted and non-coplanar structure into the polymer backbone. Drawing inspiration from previous research, three benzimidazole-based diamine monomers with twisted non-coplanar structures were designed and synthesized by modulating the relative positions of amino groups and the structures of substituents. These monomers were subsequently polymerized with two dianhydrides, namely 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), yielding two series of polybenzimidazole-imides (PBIIs): semi-aromatic and fully aromatic polymers, respectively. The resulting semiaromatic polymer films demonstrated a combination of excellent thermal resistance, with glass transition temperature (Tg) exceeding 400 degrees C, and high optical transparency, exhibiting over 80% transmittance at 400 nm (T400). This work not only provides an effective molecular design strategy for developing high-performance CPI materials but also expands the application prospects of PBII materials in the field of high-temperature optical devices.

The escalating complexity of service environments demands lightweight materials that integrate efficient sound absorption, thermal insulation, and flame retardancy. While polymer aerogels show immense potential, achieving such functional integration without compromising structural integrity remains a persistent challenge. We propose a "fiber-network toughening" strategy to fabricate polyetherimide (PEI) fiber-reinforced polyimide (PI) composite aerogels via directional freezing and thermal imidization. Serving as a critical 3D structural motif, the flexible PEI fiber network imparts superior load-bearing and stress-transfer capabilities to the matrix, effectively overcoming the inherent mechanical limitations of traditional aerogels. Our results demonstrate that tuning the fiber content enables an optimal balance among mechanical, acoustic, and thermal properties. Notably, the PPA-2 sample exhibits exceptional comprehensive performance: it combines low thermal conductivity (30.79 m- 1 K-1) and a high limiting oxygen index (47 %) with a peak sound absorption coefficient of 0.99 across the 250-6300 Hz range. Remarkably, its structural and acoustic integrity remains intact even after 1000 compression cycles at 50 % strain. This work offers a versatile design principle for developing lightweight, multifunctional protective materials tailored for aerospace and precision instrument applications.

Lightweight and multifunctional electromagnetic interference (EMI) shielding materials are in urgent demand for advanced electronic devices used in harsh environments. In this work, honeycomb PIA-Cu@MXene composite aerogels with excellent electromagnetic shielding and thermal properties were prepared through a synergistic strategy of cation-pi interaction-guided structural control, directional freeze-drying, and repeated vacuum impregnation. Cu2+-mediated cation-pi interactions contributed to a uniform and highly oriented honeycomb structure, which improved the mechanical robustness of the material. Meanwhile, uniformly dispersed Ti3C2Tx MXene nanosheets constructed a continuous three-dimensional conductive network. The aerogels exhibited outstanding absorption-dominated EMI shielding performance in the X-band. At 3 mm, the total shielding effectiveness (SET) of the optimized composite (PIC0.2M6 with 20 mol% Cu2+ and 6 mg mL(-1) MXene suspension) was 22% higher than that of the copper-free counterpart (PIC0M6). The SET reached 53.2 dB (specific shielding effectiveness SSE/t approximate to 1642 dB cm(2) g(-1)) at 5 mm and 86.1 dB at 7 mm. The composite also possessed low thermal conductivity (similar to 0.0511 W m(-1) K-1) and good thermal stability, while maintaining stable shielding performance (SET > 20 dB) under liquid-nitrogen freezing, high temperature, and ultrasonic treatment. This study provides an effective structural and interfacial design for developing lightweight, mechanically stable polymer/MXene-based EMI shielding materials with enhanced thermal management.

In the aerospace field, the intricate working conditions impose stringent requirements on the application of electromagnetic interference (EMI) shielding materials. Such materials not only need to fulfill the EMI shielding performance criteria but also must possess the capability to endure high temperature and exhibit favorable mechanical property. In the present study, anisotropic composite aerogels were fabricated through directional freezing and thermal imidization, with polyimide (PI) serving as the foundational matrix, polyimide nanofibers (PINF) functioning as reinforcements and incorporating multi-walled carbon nanotubes (MWCNTs). These composite aerogels demonstrated remarkable thermal stability, with the weight loss of 5 % up to 565 degrees C, along with excellent flame retardancy. The incorporation of PINF served to interconnect the internal structure of the aerogels, enhancing the mechanical property, as evidenced by an elastic modulus reaching up to 275 KPa. Furthermore, the EMI shielding performance of anisotropic composite aerogels was also systematically analyzed. The average shielding effectiveness (SET) of the 9-mm-thick aerogel (PPC-1) within the X-band attained 79.7 dB in the vertical direction and 61.2 dB in the horizontal direction, signifying excellent EMI resistance. These composite aerogels hold great promise for application in the demanding aerospace industry characterized by complex environments. Overall, this study provides a novel approach for preparing composite aerogels possessing lightweight, high-strength and high-efficiency EMI shielding performance, thereby making a valuable contribution to the relevant research field.

Polyimide (PI) films with ultra-high glass transition temperature (Tg) and low coefficient of linear thermal expansion (CTE) have great potential in flexible, foldable advanced optoelectronic materials. In order to make PI films better suited for flexible electronic devices, this research tried to introduce acridone groups into the diamine backbone and successfully designed and synthesized two isomeric diamine monomers: 2,7-diaminoacridin-9-ketones (3a) and 2,6-diaminoacridin-9-ketones (3b). Due to the presence of linear rigid acridone groups and strong intermolecular hydrogen bonds, the prepared novel aromatic PI films (3a-BPDA and 3b-BPDA) through a two-step method had excellent high-temperature resistance (Td5% = 565.15 degrees C and 551.04 degrees C; Tg = 469.05 degrees C and 442.58 degrees C) and low linear thermal expansion coefficients (CTE = 24.50 and 17.19 ppm K-1). In addition, this study further elucidated the influence of the acridone group and the varying linearity of diamine monomers on tight-chain fillers, revealing the successful incorporation mechanism of these components into polyimide polymer chains, providing a new insight for exploring the application of the acridone group in polyimide systems and developing higher-performance polyimide film materials.

Membranes with low dielectric constant and high moisture resistance are the key material for miniaturized and integrated communication equipment as an interlayer dielectric layer. Here, a series of cross-linked PI aerogel membranes were prepared by co-polymerization and scraping coating technology. The introduction of the fluorinated blocks and benzimidazole ring structures can consequently garner novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance. The dielectric constants of the sample membranes are as low as 1.33 at 1 KHz and 1.32 at 1 MHz with dielectric loss as low as 0.0079 at 1 KHz and 0.0035 at 1 MHz. The water contact angle can reach 107.35 degrees with a surface roughness value of 30.428 nm. Moreover, the PI aerogel membranes have high specific surface area and excellent thermal and mechanical properties. The thermal conductivity as low as 35.4 mW m(-1) K-1 at room temperature indicates excellent thermal insulation performance. PIAM-2 is suitable as an interlayer dielectric layer for electronic components under harsh environment. In addition, the influence of surface roughness on surface wettability was also elaborated on which can provide a feasible method for the preparation of low dielectric materials with moisture resistance.

Polyimide (PI) aerogels have various applications in aerospace, national defense, military industry, and rail transit equipment. This paper reports a series of ultra-lightweight, high elasticity, high strength, low thermal conductivity, and high flame retardant rGO/PI nanocomposite aerogels prepared by the ice templating method. The effects of freezing processes (unidirectional freezing and random freezing), chemical composition, and environmental temperature (- 196-200 degrees C) on the morphology, mechanical, and thermal properties of the aerogels were systematically studied. The results indicated that unidirectional aerogels exhibit anisotropic mechanical properties and thermal performance. Compression in the horizontal direction showed high elasticity, high fatigue resistance, and superior thermal insulation. Meanwhile, in the vertical direction, it demonstrated high strength (PI-G-9 reaching 14 MPa). After 10,000 cycles of compression in the horizontal direction (at 50 % strain), the unidirectional PI-G-5 aerogel still retains 90.32 % height retention, and 78.5 % stress retention, and exhibited a low stable energy loss coefficient (22.11 %). It also possessed a low thermal conductivity (32.8 mW m- 1 K-1) and demonstrated good thermal insulation performance by sustaining at 200 degrees C for 30 min. Interestingly, the elasticity of the aerogels was enhanced with decreasing temperatures, achieving a height recovery rate of up to 100 % when compressed in liquid nitrogen. More importantly, the rGO/PI aerogels could be utilized over a wide temperature range (- 196-200 degrees C) and had a high limiting oxygen index (LOI) ranging from 43.3 to 48.1 %. Therefore, this work may provide a viable approach for designing thermal insulation and flameretardant protective materials with excellent mechanical properties that are suitable for harsh environments.

To synthesize colorless superheat-resistant polyimide films, one of the valid approaches is the incorporation of the asymmetric and warped structures in the main chain. Applying this approach on 5(6)-amino-2-(4-aminobenzene)benzimidazole (PABZ) and changing its linearity, 6, 5 '-diamine-2 '-methyl-1-methyl-2-phenylbenzimidazole (5a) and 6, 3 '-diamine-2 '-methyl-1-methyl-2-phenylbenzimidazole (5b) were devised and synthesized successfully, then polymerized with 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA). The prepared poly(benzimidazole imide)s (PBIIs) with the rigid main chain and loose packing had the excellent heat-resistant level (T-g > 400 degrees C) and optical properties (T-400 > 80%). Besides, the alterations resulting from various linearities were discussed comprehensively. This research is beneficial to the application of optical field, providing a promising candidate of heat-resistant colorless materials.

The exceptional hydrophilicity and charge equilibrium of zwitterionic polymers render them highly desirable as antifouling materials. In this study, a novel zwitterionic copolymer Poly(2-aminoethyl methacrylate-Ethyl acrylatesulfopropyl piperidine salt) [P(AE-EA)] was successfully synthesized. Subsequently, a novel tight-ultrafiltration (t-UF) antifouling membrane employed for dye/salt separation was fabricated by co-depositing dopamine (DA) and P(AE-EA) onto the polyphenylene sulfone (PPSU) membrane substrate. The polydopamine (PDA) and P(AE-EA) are covalently linked through the formation of a covalent bond via Michael addition and Schiff base reactions. By regulating the ratio of PDA and P(AE-EA), the optimized membrane shows a denser and hydrophilic selective layer. The composition and characteristics of the membrane are investigated by serial characterization. The electrostatic adsorption between the membrane surface and the pollutant can be effectively weakened by the incorporation of a zwitterionic polymer P(AE-EA) with neutral charged and hydrophilicity. The modified membrane demonstrates exceptional antifouling performance for BSA, high rejection towards both negatively and positively charged dyes (Congo red, Methylene blue, Methyl orange and Rhodamine B), as well as efficient salt permeance for NaCl, Na2SO4, MgCl2, Mg2SO4 in comparison to that of the pure PPSU membrane. The results presented herein demonstrate the remarkable potential of the novel zwitterionic t-UF membrane for effectively separating dye/salt mixture solutions in the textile industry.

Flexible conductive polyimide aerogels used for piezoresistive pressure sensors in harsh environments are often limited by brittleness, structural collapse, low elastic recovery, low sensitivity, and narrow pressure detection range. Herein, we report a simple and green method of ice-templating unidirectional solidification combined with freeze-drying and thermal imidization to obtain a flexible reduced graphene oxide/polyimide (rGO/PI) nanocomposite aerogels with a double crosslinked structure, which achieve a significant transformation of PI aerogels from brittleness to high flexibility. The strong layered structure and dense interlaminar porous network are established by the covalent crosslinking of 1,3,5-triaminophenoxybenzene (TAB) and the hydrogen bonding crosslinking of graphene oxide (GO), imparting the double crosslinked rGO/PI aerogels with unique "porous honeycomb" structure and excellent mechanical properties. Due to the synergistic effect of TAB, rGO, PI, and unidirectional freezing process, the double crosslinked rGO/PI nanocomposite aerogel shows low density (25 mg/cm3), high compression cycle stability (3000 cycles), wide pressure detection range (0-85.1 kPa), extremely short response time (about 129 ms) and excellent environmental resistance (maintaining high structural stability and pressure response even at high temperatures of 180 degrees C and low temperatures of-50 degrees C), suitable for detecting various motion signals. It is proved that the elastic double crosslinked rGO/PI nanocomposite aerogels have potential applications serving as candidate materials for piezoresistive sensors and wearable electronic protective equipment in the fields of national defense, military industry, aerospace, and other fields in extreme environments.

Polyimide (PI) aerogels, serving as thermal insulation materials in extreme environments, stand out for their exceptional high temperature stability and superb thermal insulation properties, rendering them ideal for aerospace, transportation, and specialized equipment industries. However, conventionally synthesized PI aerogels suffer from significant drawbacks in mechanical properties and thermal stability, limiting their practical applications. To overcome this challenge, we successfully synthesized polyimide aerogels using biphenyl-3,3,4,4 ' tetracarboxylic dianhydride (BPDA), 5-amino-2-(4-aminophenyl)benzimidazole (PABZ), and 5-amino-2-(4-aminophenyl)benzoxazole (APBO) followed by supercritical carbon dioxide drying. These synthesized PIs exhibit remarkable thermal stability, with high thermal weight loss temperatures (T-d5 %=595-611 degrees C) and high glass transition temperatures. Additionally, these novel PI aerogels demonstrate exceptional thermal insulation properties, high specific surface area, and extremely small pore size. Furthermore, boasting a low dielectric constant (epsilon=1.72), these newly developed PI aerogels offer along with excellent mechanical properties, holding substantial promise for applications in the forthcoming generation of advanced aerospace and specialized equipment materials.

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 9.48MPa and modulus of up to 232.4 Mpa，along with compression Young’s modulus increased by 173% (up to 28.7MPa) 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 10MHz) 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 100-250 °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.

Two novel electrochromic aromatic polyimides (named as TPA-BIA-PI and TPA-BIB-PI, respectively) with pendent benzimidazole group were synthesized from 1,2-Diphenyl-N,N′-di-4-aminophenyl-5-amino-benzimidazole and 4-Amino-4′-aminophenyl-4″-1-phenyl-benzimidazolyl-phenyl-aniline with 4,4′-(hexafluoroisopropane) phthalic anhydride (6FDA) via two-step polymerization process, respectively. Then, polyimide films were prepared on ITO-conductive glass by electrostatic spraying, and their electrochromic properties were studied. The results showed that due to the π-π* transitions, the maximum UV–Vis absorption bands of TPA-BIA-PI and TPA-BIB-PI films were located at about 314 nm and 346 nm, respectively. A pair of reversible redox peaks of TPA-BIA-PI and TPA-BIB-PI films that were associated with noticeable color changed from original yellow to dark blue and green were observed in the cyclic voltammetry (CV) test. With increasing voltage, new absorption peaks of TPA-BIA-PI and TPA-BIB-PI films emerged at 755 nm and 762 nm, respectively. The switching/bleaching times of TPA-BIA-PI and TPA-BIB-PI films were 13 s/16 s and 13.9 s/9.5 s, respectively, showing that these polyimides can be used as novel electrochromic materials.

The poor mechanical properties of polyimide (PI) aerogels made from biphenyl-3,3 ',4,4 '-tetracarboxylic diany-dride (BPDA) and 4,4 '-oxidianiline (ODA) limit their application. In this paper, an aromatic heterocyclic diamine, 5-amino-2-(4-aminophenyl)benzimidazole (PABZ) was introduced into the BPDA/ODA backbone to improve the comprehensive performance. The obtained PI aerogels represented excellent mechanical properties. The compressive Young's modulus was up to 53.9 MPa and the stress at 10 % strain was as high as 2.39 MPa. Meanwhile, the tensile Young's modulus ranged from 234 to 464 MPa and the tensile strength was up to 2.40 MPa. At the same time, all formulations of PI aerogels possessed outstanding thermal insulation, superb flame resistant and self-extinguishing performances, promising to be good candidates for special protective materials. Furthermore, the correlation between changes in morphology and structure resulting from the introduction of PABZ and PI aerogel properties was systematically analyzed.

Membrane fouling is a key challenge in the process of utilizing polyphenylene sulfone(PPSU) ultrafiltration (UF) membranes. To address this issue, an amino-functionalized poly(ionic liquid), poly(1-vinyl-3-propylamine imidazolium bis(trifluoromethane sulfonyl) imide) (PIL[TFSI]), was synthesized via free radical polymerization and incorporated into the prepared UF membranes-based PPSU with nanochannels through nonsolvent induced phase separation method. 1H NMR, ATR-FTIR, XPS and EDS spectra verified the introduction of PIL[TFSI]. The AFM and SEM images showed the membrane possessed a classical asymmetrical structure, featuring a higher surface roughness and dense cortex with pits. The decreased water contact angle by the incorporation of PIL [TFSI] indicates the formation of an improved hydrophilic membrane surface. The hydrophilicity of the blended membranes was enhanced by the increasing incorporation of PIL[TFSI]. Meanwhile, the flux decreased slightly, but the selectivity improved significantly. The PIL[TFSI]/PPSU UF membrane with 5% PIL[TFSI] maintained a flux (275 L/m2 h) and a high rejection for bovine serum albumin (BSA) (>99.9%). Additionally, the blended membrane has a superior removal performance for Congo red (>99.9%) and Evans blue (>99.9%). More importantly, the PIL[TFSI]/PPSU UF membranes present excellent antifouling with an increased flux recovery rate from 60.2% to 91.1%. Furthermore, the existence of hydrogen bonds and 7C-7C interactions between PIL[TFSI] and PPSU is conducive to the good stability and sustained hydrophilicity of blended membrane even after continuous immersion for a month.

The lunar base is not only an experimental station for extraterrestrial space exploration but also a dwelling for humans performing this exploration. Building a lunar base presents numerous obstacles and requires environmental perception, feedback design, and construction methods. An integrated fabrication process that incorporates design, 3D printing workflow, and construction details to build a bionic, reconfigurable and high-performance lunar base prototype is presented in this paper. The research comprises the study of the lunar regolith 3D printing mechanism, the real-time control of powder laying and compaction procedure, and the development of a 3D printing tool end system. In this paper, many scientific questions regarding in situ fabrication on the lunar surface are raised and addressed with the proposal of a progressive optimization design method, the molding principle, and gradation strategy of lunar soil-polyaryletherketone (PAEK) hybrid powder, and the principle of dual-light field 3D laser printing. The feasibility of the technical strategy proposed in this paper is verified by the presented empirical samples.

Novel diamines containing spirobisbenzoxazole scaffold structure were successfully synthesized. These diamines were homopolymerized with commercial 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and cyclohexanedianhydride (H'PMDA) to prepare a series of benzoxazole based polyimides (PBOIs). The obtained PBOIs exhibited good organic solubility and outstanding thermal properties, including glass transition temperature (T-g) of 355-400 degrees C and 5% thermal decomposition temperatures (T-d5%) of 474-490 degrees C. Meanwhile, these polymer films exhibited excellent mechanical strength, such as tensile strength of 79.4-92.1 MPa and elongation at break of 19.5%similar to 31.2%. In addition, such PBOIs have been proved to be novel microporous polymer with pore width distribution of 5-7 angstrom and BET surface area of 281-378 m(2)/g. The permeability-selectivity relationship of H'PMDA based PBOIs was close to the 2008 Robeson upper bound for CO2/CH4 and O-2/N-2 gas pairs, showing promise in the field of gas separation.