Polyimide Polymer Research Articles

Structural design of two types of composites with high resistance to atomic oxygen attack based on polyimide matrices: a molecular dynamics simulation study

Because of their exceptional properties, polyimide (PI) polymers are widely used in various types of spacecraft. However, in low Earth orbit, spacecraft using these polymers are susceptible to atomic oxygen (AO) erosion, which will cause them to lose their original performance. Covering the PI surface with a protective coating and adding fillers to the PI matrix are two traditional methods to improve the AO erosion resistance of PI. However, a single protective method does not provide a good protective effect and does not necessarily balance the relationship between the AO resistance of the composites and other properties, such as mechanical properties. The structural design of composites can perfectly solve such problems. Therefore, two kinds of AO-resistant materials based on the PI matrix are designed in this paper, one is a hybrid-filled composite with nano-silica filler and graphene filler, and the other is a double-layer coated composite based on the structural design of a traditional bulletproof vest. And the AO incidence simulation of these two types of materials was carried out using ReaxFF-based MD simulation. The results show that the mixed filling of graphene and nano-silica not only greatly improves the AO resistance of the PI matrix, but also greatly improves the tensile mechanical properties of the matrix by adjusting the appropriate mixing ratio. The structure of PI-Gr-SiO2 (The structures are PI, Gr and SiO2 from bottom up, respectively. SiO2 will be the first to take the impact of AO.) possesses excellent resistance to AO erosion, and at the end of 64 ps of AO erosion, the PI matrix did not suffer any damage. This paper provides a new idea of material structure design using the MD method, which provides a new approach to improve the AO erosion resistance of PI and is expected to design new composites adapted to a variety of extreme environments in the future.

From Molecular Design to Practical Applications: Strategies for Enhancing the Optical and Thermal Performance of Polyimide Films.

Polyimide (PI) films are well recognized for their outstanding chemical resistance, radiation resistance, thermal properties, and mechanical strength, rendering them highly valuable in advanced fields such as aerospace, sophisticated electronic components, and semiconductors. However, improving their optical transparency while maintaining excellent thermal properties remains a significant challenge. This review systematically checks over recent advancements in enhancing the optical and thermal performance of PI films, focusing on various strategies through molecular design. These strategies include optimizing the main chain, side chain, non-coplanar structures, and endcap groups. Rigid and flexible structural characteristics in the proper combination can contribute to the balance thermal stability and optical transparency. Introducing fluorinated substituents and bulky side groups significantly reduces the formation of charge transfer complexes, enhancing both transparency and thermal properties. Non-coplanar structures, such as spiro and cardo configurations, further improve the optical properties while maintaining thermal stability. Future research trends include nanoparticle doping, intrinsic microporous PI polymers, photosensitive polyimides, machine learning-assisted molecular design, and metal coating techniques, which are expected to further enhance the comprehensive optical and thermal performance of PI films and expand their applications in flexible displays, solar cells, and high-performance electronic devices. Overall, systematic molecular design and optimization have significantly improved the optical and thermal performance of PI films, showing broad application prospects. This review aims to provide researchers with valuable references, stimulate more innovative research and applications, and promote the deep integration of PI films into modern technology and industry.

Polyimide strengthened cement mortar

Abstract 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.

Flexible IGZO TFT Technology for Shift Register Drivers

AbstractActive sensing matrices play a pivotal role in various electronic devices, including optical and X‐ray imaging arrays, electronic skins, and artificial tactile arrays, among others. These matrices function through a thin‐film active switching mechanism, allowing for the scanning of rows and columns by external circuitry to read the sensory signals of individual pixels. Recently, indium–gallium‐zinc oxide thin‐film transistors (IGZO TFTs) have emerged as highly promising technology in the realm of flexible electronics. They enable the large‐scale integration of functional circuits on flexible substrates. Shift registers are commonly employed as peripheral scanning circuits to sequentially address active‐matrix arrays. To enhance system compactness and minimize external electrical connections, it is imperative to seamlessly integrate shift registers within the active matrices. However, contemporary flexible IGZO‐based shift registers suffer from high operating voltages and low frequencies, which constrain their applicability in high‐performance flexible sensors and displays. In response to this challenge, a breakthrough is presented in the form of low‐voltage, high‐frequency bootstrap shift registers implemented with flexible IGZO technology. The approach involves utilizing SU‐8 buffered polyimide (PI) polymer foils as substrates. These foils boast an exceptional level of surface smoothness, significantly increasing the yield and performance of electronic components, including vias, IGZO TFTs, and capacitors used in the shift register circuitry. Additionally, HfO2/Al2O3/HfO2 sandwich structures are employed as high‐k dielectric layers to reduce the operational voltage. Thanks to the innovative circuit design and optimized fabrication methods, the 16‐stage shift register can operate at just 1.8 V with a frequency of 15 kHz. This breakthrough promises to have a profound impact on a wide range of applications for driving flexible active‐matrix electronic systems.

Investigation into the thermal noise propagation mechanism within composite materials for gravitational wave detection systems

The thermal transmission properties of polymer-based composites, commonly used in satellites, are crucial for high-precision thermal management applications. The study constructed the structures of polyimide polymers and polyimide/graphene interfaces based on molecular dynamics and fluctuation dissipation theorem. Optical parameters were determined through first-principles calculations, and the thermal transport from a microthermal source was simulated using Reverse Non-Equilibrium Molecular Dynamics (RNEMD) and the modified four-dimensional transfer matrix method (M4D-TMM). Simulations of polymers, interface structures, and interfacial thermal radiation models investigated the transmission dynamics of microthermal sources during heat transport. Findings showed that the differences in the temperature fields formed within the polymer from microthermal heat sources were less than 20 K for heat source inputs ranging from 0.002 W/m² to 20 GW/m². With a microthermal source, the heat diffusion was extensive, the heat transport was continuous, and the temperature field remained stable. At the level of the heat source up to the intermolecular energy level, the temperature field distribution showed significant instability, leading to nonlinear effects. Within the interface structure, the continuity of heat diffusion increased as the heat source intensified. The interface structure demonstrated enhanced temperature sensitivity and improved stability, with minimal fluctuations of only 0.59 %. The increase in heat flux perpendicular to the interface structure was ascribed to near-field radiative heat transfer. As the temperature difference decreased to less than 0.1 K, the influence of evanescent waves on radiative heat flux nearly disappeared. Phonon polaritons maintained temperature stability during thermal transport through micro- and nanoscale gaps. Integrating thermal conduction principles in polyimide polymers and interface structures with near-field thermal radiation provides a theoretical framework for high-precision thermal management in gravitational wave detection.

Effects of the Mesoporous Filler and Oleophilic Property on the Tribological Behavior of Polyetheretherketone Composites.

Porous composites, such as polyimide and polyetheretherketone (PEEK) polymer composites, became more attractive as a result of excellent specific strength, lightweightness, and smart lubrication. However, revealing the influence of a porous filler on the friction behaviors of polymer composites remains a challenge. The current work examines the effects of the pore structure and wettability on the mechanical and tribological performances of polymer composites reinforced with fillers. Three kinds of particles (non-porous, porous, and oleophobic porous) act as fillers within PEEK, respectively. It was identified that adding porous zeolite particles into PEEK slightly decreased the mechanical property. The zeolite particles significantly increased the oil adsorption of the composite, leading to a significant increase in the friction coefficient at 10 wt % content. However, the friction coefficient of the PEEK composite filled with 20 wt % modified zeolite was relatively low as a result of the weak adsorption. The interface analyses indicated that the thickness of the oil film was controlled via porous structures, changing the lubrication regime of the tribopair. The reason is the appropriate adsorption of oil and the release of zeolite from the composites during the friction process. These results can offer technical guidance to control the friction behaviors of composites under oil-lubricating conditions by a porous particle and pore modification.

Carbon dioxide hydrogenation to methanol by flame-deposited CuO/ZrO2-polymer membrane reactors

Carbon dioxide hydrogenation for methanol synthesis, within the framework of carbon dioxide utilization represents a promising strategy. Nevertheless, high conversion of carbon dioxide into methanol presents significant challenges, primarily arising from thermodynamic constraints and catalyst deactivation due to the formation of water as a by-product. In response to these challenges, this investigation focused on the development of an innovative hybrid catalytic membrane reactor utilizing flexible polymeric membranes with flame-made catalysts. The nanostructured CuO/ZrO2 thin layers were synthesized by flame spray pyrolysis and directly deposited on two polyimide polymers and polybenzimidazole membranes. The CuO/ZrO2-polymer membranes are reduced by H2 at 300 °C resulting in Cu/ZrO2-polymer nanocomposites. This novel hybrid membrane design facilitated the efficient separation of by-product water from the reaction environment, effectively promoting carbon dioxide conversion and ultimately leading to enhanced methanol production rate. At 200 °C and 20 bar, these catalytic membrane reactors demonstrate exceptional performance, achieving 113 % improvement in carbon dioxide conversion and a remarkable 106 % increase in methanol production rate compared to conventional catalytic fixed bed reactors. Overall, the catalytic membrane, synthesized using flame spray pyrolysis, has shown long-term stability and ability to suppress catalyst deactivation caused by water, ensuring sustained catalyst stability throughout the reaction.

Metalized Plastic Current Collectors Incorporated with Halloysite Nanotubes toward Highly Safe Lithium‐Ion Batteries

AbstractMetalized plastic current collectors (MPCCs) have shown potential in improving the energy density and safety of lithium‐ion batteries (LIBs). However, the poor mechanical strength, weak interfacial adhesion force, and surface metal corrosion have impeded the practical application of MPCCs. Here, an innovative engineering of MPCCs is proposed by incorporating halloysite nanotubes (HNTs) as fillers into polyimide (PI) polymer layer, which is further coated with two thin copper (Cu) layers. Because of the strong bonding between HNTs surface and the PI precursor, HNTs improve the mechanical strength of PI‐HNTs composite film, reinforce the interfacial adhesion force between the PI‐HNTs film and the coated Cu layer, and suppress the Cu corrosion by electrolyte. The prepared MPCCs exhibit a low mass density and only account about one‐fifth of the density of commercial Cu CCs. Furthermore, the PI‐HNTs‐Cu composite demonstrates significantly enhanced interfacial adhesion force doubled to 4 N cm−1 along with prolonged stability under electrolyte immersion and electrochemical reaction conditions, and delivers a high fracture strength of 125 MPa. LIBs assembled with MPCCs deliver a twice higher discharge capacity compared to battery with Cu CCs and reach a long‐term cycle capacity retention as high as 92.9% at 0.5 C after 500 cycles.

Polysulfide-ene polymerization of bisacrylamides and bismaleimides toward sulphur-rich polymers

Given the ever-increasing importance of developing more sustainable solutions for the fabrication and engineering of polymeric materials, alternative building blocks to the petroleum-derived chemicals are gaining growing interest. In addition to its natural abundance, elemental sulfur is produced industrially in vast quantities which is primarily obtained as a side product from oil refineries and gas purification plants. Thus, elemental sulfur has been prospected as a sustainable resource for the fabrication of structurally diverse polymers. In this study an efficient methodology to obtain sulfur-rich polymers from elemental sulfur-derived polysulfide salts is reported. Polysulfide-ene step growth polymerization of bisacrylamide and bismaleimide-based monomers with bifunctional disodium pentasulfide (Na2S5) generated structurally diverse polyamide and polyimide copolymers incorporating polysulfide chains on the polymer backbones. Copolymers up to 31.8 kDa molecular weight (Mn) and 94% monomerconversions were efficiently obtained under ambient temperature conditions and without the need of any metal or organo-catalyst. By choosing various bifunctional ene monomers, structurally diverse and tailorable linear copolymers were obtained. The methodology was also extended to the fabrication of sulfur-rich crosslinked polymers by employing a multifunctional thiolate-based crosslinker. As a potential application, fabricated crosslinked polymers were employed as adsorbents to remove toxic mercury ions from water. The reported synthetic strategy demonstrated the efficiency of polysulfide-ene reaction to synthesize sulfur-rich polyamide and polyimide polymers and could broaden the available polymerization reaction tools that employelemental sulfur-derived polysulfide salts in functional polymer synthesis.

Significantly Enhanced Energy Density of Polyvinylidene Fluoride/Polyimide-Based Nanocomposites by Core-Shell BaTiO3@SiO2.

Improving the limited energy storage capacity of dielectric materials has long been an attractive challenge. In this work, a four-phase hybridized nanocomposite was designed. The linear polymer polyimide (PI) was added to the ferroelectric polymer polyvinylidene fluoride (PVDF) and compounded with a nanoceramic BT@SiO2 with a core-shell structure. The results show that PVDF-PI/BT@SiO2 nanocomposites prepared by a straightforward spin-coating method have a significantly increased discharge energy density. The polymer blends obtain a tightly extended conformation in the amorphous region. Also, this provides an excellent matrix environment for the homogeneous dispersion of fillers. The core-shell structure, as a physical barrier, not only hinders the expansion of the breakdown path but also extends multiple polarization surfaces with gradient variations at the microscopic level. Therefore, the synergistic effect generated by polymer blending and core-shell structure effectively enhances the dielectric and stored energy characteristics of nanocomposites. The dielectric constant is stable at 11.39-18.7, and the dielectric loss is always lower than 0.136. The discharge energy density is 2.5 J/cm3, almost 110% higher than that of the BOPP films (about 1.2 J/cm3). These experimental results suggest that the composite system using core-shell structure and polymer blending is a new way to improve the energy density of dielectric materials.

The propensity for covalent organic frameworks to template polymer entanglement.

The introduction of molecularly woven three-dimensional (3D) covalent organic framework (COF) crystals into polymers of varying types invokes different forms of contact between filler and polymer. Whereas the combination of woven COFs with amorphous and brittle polymethyl methacrylate results in surface interactions, the use of the liquid-crystalline polymer polyimide induces the formation of polymer-COF junctions. These junctions are generated by the threading of polymer chains through the pores of the nanocrystals, thus allowing for spatial arrangement of polymer strands. This offers a programmable pathway for unthreading polymer strands under stress and leads to the in situ formation of high-aspect-ratio nanofibrils, which dissipate energy during the fracture. Polymer-COF junctions also strengthen the filler-matrix interfaces and lower the percolation thresholds of the composites, enhancing strength, ductility, and toughness of the composites by adding small amounts (~1 weight %) of woven COF nanocrystals. The ability of the polymer strands to closely interact with the woven framework is highlighted as the main parameter to forming these junctions, thus affecting polymer chain penetration and conformation.

Simultaneous photocatalytic degradation and SERS detection of tetracycline with self-sustainable and recyclable ternary PI/TiO2/Ag flexible microfibers

Facile and efficient photocatalysts using sunlight, as well as fast and sensitive surface-enhanced Raman spectroscopy (SERS) substrates, are urgently needed for practical degradation of tetracycline (TC). To meet these requirements, a new paradigm for PI/TiO2/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide (TiO2), the noble metal silver (Ag) and the conjugated polymer polyimide (PI) was developed by engineering a simple method. Under sunlight, the photocatalytic characteristics of the PI/TiO2/Ag flexible microfibers containing varying amounts of Ag quantum dots (QDs) were evaluated with photocatalytic degradation of TC in aqueous solution. The results demonstrated that the amount of Ag affected the photocatalytic activity. Among the tested samples, PI/TiO2/Ag-0.07 (93.1%) exhibited a higher photocatalytic degradation rate than PI/TiO2 (25.7%), PI/TiO2/Ag-0.05 (77.7%), and PI/TiO2/Ag-0.09 (63.3%). This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism. Moreover, the PI/TiO2/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection, as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10–10 moles per liter. The excellent photocatalytic performance and SERS detection capability of the PI/TiO2/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO2 and also from the outstanding plasmonic resonance and visible light absorptivity of Ag, along with immobilization by the PI. The successful synthesis of PI/TiO2/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.

Energy storage properties of high polarization 2D-Na0.5Bi0.5TiO3 reinforced polyimide composites

With the continuous development of society, the energy demand is also increasing, and the consumption of fossil fuels is becoming more and more serious. Dielectric capacitors are widely used in electronic devices due to their advantages of fast charging and discharging speed and high power density. In this work, 2D-Na0.5Bi0.5TiO3 (2D-NBT) filler and polyimide (PI) polymer matrix were compounded to prepare 2D-NBT/PI composites, and the energy storage performance of the composites was improved by surface modification of the filler and the design of 'sandwich' structure. The prepared samples were analyzed by XRD, SEM and dielectric properties. For 2D-NBT/PI single-layer composites, when the volume fraction of NBT powder is 0.25 vol.%, the energy storage density of the composites reaches 11.11 J/cm3 under the electric field of 400 kV/mm. For the 'sandwich' structure 2D-NBT/PI composites, when the system of 2D-NBT/PI composites is 0.25-0-0.25, the energy storage density of the composites reaches 12.44 J/cm3 under the electric field of 440 kV/mm.

Investigation of the mechanical, thermal and dielectric properties of electrical corrosion resistance glass reinforced polyimide-based composite produced by spark plasma sintering

Polyimide polymer matrix composites have gained numerous attentions in the design and fabrication of components for automobile, aerospace, and electronics applications as a result of their outstanding properties. Composites are currently replacing polymers as structural, insulation and dielectric materials, and the improvement of mechanical, thermal, and dielectric properties of polyimide (PI) becomes important. Thus, in this paper, the enhancement of the mechanical, thermal stability, and dielectric properties of PI composites with boron-free E-glass (electrical corrosion resistance (ECR) glass) reinforcements (0, 5, 10, and 15 wt%) using Spark Plasma Sintering (SPS) process is presented. X-ray diffractometer, scanning electron microscope (SEM), nanoindentation tests, thermogravimetric analyser, and LCR meter tester were used to investigate the morphology, mechanical, thermal, and dielectric properties of the developed composites, respectively. The SEM results revealed that the ECR-glass powder particles were well dispersed in the PI matrix. The introduction of the ECR into the PI matrix, improves its hardness, stiffness, and modulus. From the obtained results, a notable improvement in its hardness (9.36%), stiffness (30.77%), and modulus (43.58%) was revealed for ECR/PI loaded with 15 wt% ECR compared to pure PI. The thermal stability of the PI composites was observed to be improved with the incorporation of the ECR-glass particles. The heat resistance index of the PI was recorded to be improved by 3.8% at 15 wt% ECR incorporation. Furthermore, the composites depicted low dielectric constant and dissipation factor. In consideration, the obtained properties make the composites promising for mechanical load-bearing, thermal management and electronics applications.

IMPROVING THE PERFORMANCE OF HYBRID BIOCOMPOSITE MATERIALS USING EPOXY, VINYL ESTER AND POLYIMIDE POLYMER MATRIX: COMPARATIVE STUDY

The present study aims to assess the impact of alfa and date palm natural fibers as reinforcement for epoxy, vinyl ester, and polyimide polymer (Alfa-Date palm/epoxy, Alfa-Date palm/vinyl ester, and Alfa-date palm/polyimide) through a genetic approach. The study employs a genetic simulation rooted in the Weibull formalism, employing genetic operators such as selection, crossing, and mutation for a nuanced evaluation of the damage at the fiber-matrix interface across the studied materials. The genetic algorithm results authentically capture the intrinsic behaviour of these materials, emphasising key mechanical properties like Young’s Modulus, deformation, and stress at break. The obtained results highlight that the matrix showing the highest Young’s modulus value at its fiber- matrix interface exhibits superior strength. These conclusions align with contemporary advancements in natural fiber-reinforced composite materials tailored for diverse industries and eco-friendly applications.

Predicting and screening high-performance polyimide membranes using negative correlation based deep ensemble methods.

Polyimide polymer membranes have become critical materials in gas separation and storage applications due to their high selectivity and excellent permeability. However, with over 107 known types of polyimides, relying solely on experimental research means potential high-performance candidates are likely to be overlooked. This study employs a deep learning method optimized by negative correlation ensemble techniques to predict the gas permeability and selectivity of polyimide structures, enabling rapid and efficient material screening. We propose a deep neural network model based on negative correlation deep ensemble methods (DNN-NCL), using Morgan molecular fingerprints as input. The DNN-NCL model achieves an R2 value of approximately 0.95 on the test set, which is a 4% improvement over recent model performance, and effectively mitigates overfitting with a maximum discrepancy of less than 0.03 between the training and test sets. High-throughput screening of over 8 million hypothetical polymers identified hundreds of promising candidates for gas separation membranes, with 14 structures exceeding the Robeson upper bound for CO2/N2 separation. Visualization of high-throughput predictions shows that although the Robeson upper bound was never explicitly used as a model constraint, the majority of predictions are compressed below this limit, demonstrating the deep learning model's ability to reflect real-world physical conditions. Reverse analysis of model predictions using SHAP analysis achieved interpretability of the deep learning model's predictions and identified three key functional groups deemed important by the deep neural network for gas permeability: carbonyl, thiophene, and ester groups. This established a bridge between the structure and properties of polyimide materials. Additionally, we confirmed that two polyimide structures predicted by the model to have excellent CO2/N2 selectivity, namely 6-methylpyrimidin-5-amine and 1,4,5,6-tetrahydropyrimidin-2-amine, have been experimentally validated in previous studies. This research demonstrates the feasibility of using deep learning methods to explore the vast chemical space of polyimides, providing a powerful tool for discovering high-performance gas separation membranes.

(Invited) Autonomous Self-Healable Silicon Anode for Next Generation Lithium-Ion Batteries

Self-healing is a measure of material's ability to repair damage. Physical and chemical processes have been used to obtain self-healing polymers for various applications. Different approaches are involved for these systems, such as shape-memory effects, covalent-bond reform, heterogeneous systems, diffusion and flow, and the dynamics of supramolecular chemistry. Different approaches are used to achieve self-healing polymers, in particular, the role of the healing system in chemistry is highlighted, which enables thermal transients, damage repairing and reconnection. Moreover, self-healing systems and their energy storage applications are currently getting great importance. Inspired by the dynamic network structure of animal dermis, in which collagen fibril (rigid and strong) and elastin fibril (soft and elastic) crosslink through supramolecular interactions to form a sturdy and flexible material we hypothesized that the combination of a rigid conductive polymer with a soft hydrophilic polymer through proper supramolecular interactions would yield a strong and robust polymer binder.According to the literature, the external stimulus such as heat, light, pH and redox initiate the healing process. This process is known as non-autonomous self-healing when some additional external stimulus is needed. Considering the battery chemistry, it is the most functional method to choose self-healing structures and batteries with the help of hydrogen bonds in order to make the self-healing process occurs autonomously. In the literature, polymerized β-cyclodextrin (β-CD) has been used as an advanced binder for Si-nanoparticle anodes, and cracks in the electrode can be avoided with its reversible properties through supramolecular cyclodextrin or hydrogen bonding compounds[1]. Dynamic bonds such as hydrogen bonds between composites positively affect the durability of the Si anode performance. For example, the Si anode was coated by the researchers with hydrogen bond-oriented polymer binder layers based on polyimide polymer such as Upy, resulting in electrochemical performance ten times longer than conventional silicon anodes[2].Horizon projects such as BAT4EVER and HIDDEN under Battery 2030+ initiative have been investigate the integration and optimization of self-healing polymers in Li-ion battery [3]. In the scope of the BAT4EVER project, supramolecular coupling of polyaniline and polyvinyl alcohol via dynamic boronate bond yields polyaniline-polyvinyl alcohol hydrogel with outstanding tensile strength and electrochemical performance. The self-healing chemistry in the Si anode prevents unbalanced volumetric changes and cracks on the electrode surface. Thus, electrochemical performance losses are decreased. The self-healing functionalized components of lithium-ion batteries, which focus on improving and optimizing properties such as high energy density, high voltage, long life, and cycle stability, are of great importance for next-generation batteries.References Jeong, Y.K., Kwon, T.W., Lee, I., Kim, T.S., Coskun, A., Choi, J.W.: Hyperbranched β-cyclodextrin polymer as an effective multidimensional binder for silicon anodes in lithium rechargeable batteries. Nano Lett. 14, 864–870 (2014). https://doi.org/10.1021/NL404237J/SUPPL_FILE/NL404237J_SI_001.PDFYang, J., Zhang, L., Zhang, T., Wang, X., Gao, Y., Fang, Q.: Self-healing strategy for Si nanoparticles towards practical application as anode materials for Li-ion batteries. Electrochem commun. 87, 22–26 (2018). https://doi.org/10.1016/J.ELECOM.2017.12.023https://battery2030.eu/ This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement 957225 (BAT4EVER).

Thermo-mechanical properties and internal architecture of PI composites for high-pressure hydrogen applications

The efficient transport of Hydrogen is pivotal to the wide scale adaption of energy produced from renewable sources. Reciprocating piston compressors with high strength non-lubricated sealing solutions for piston and rod packing rings will be a key technology to fulfill gas purity and high-pressure gradients demands set by hydrogen applications. Polyimide polymer matrix composites have seen use in tribological applications and promise high mechanical strength and temperature resistance. The presented work describes carbon fiber reinforced Polyimide blends in comparison, characterized by complementary advanced methods to investigate their properties and potential for reciprocating compressor applications. Thermo-mechanical and tribological testing was supported by microstructure analysis utilizing synchrotron tomography and electron microscopy, pinpointing the necessity of dry lubricating additives such as PTFE. New insights in micromechanical deformation behavior of fiber reinforced polymers are given and promising fiber-reinforced polyimide compositions suitable for high-pressure hydrogen compression applications were identified.

Transformation from Knudsen diffusion to facilitated diffusion for CO2 in confined mass transfer channels of polyimide mixed matrix membranes

Incorporation of porous materials in a polymeric membrane is an effective strategy for improving the gas permeability of the resulting mixed matrix membranes (MMMs). However, effective improvement of selectivity of membrane toward CO2 separation is still a significant challenge due to the insufficient CO2 capture performance of porous materials. In this study, polyimide (PI)-based MMMs with enhanced CO2 capture performance were prepared for CO2 separation. First, an ionic liquid (IL) with a high affinity for CO2 was immobilized in the inner pore structures of two types of mesoporous silica (SiO2) molecules to form IL@SiO2 composites. These composites were used as nanofillers to construct the MMMs. The stable immobilization of IL inside the pores of the mesoporous SiO2 indicated that the IL@SiO2 and MMMs both exhibited higher adsorption selectivity for CO2. The gas solubility coefficient of the MMMs was positively proportional to their maximum gas adsorption capacity, which was determined by the gas adsorption capacity of the PI polymer and nanofillers. More interestingly, the diffusion coefficients of different gases in the MMMs were closely related to the confined mass transfer channels introduced by the nanofillers. The diffusion of CO2 in the confined mass transfer channels of MMMs was facilitated and N2 diffusion was slightly inhibited, which increased the diffusion selectivity of the resulting MMMs for CO2. Combined with Maxwell–Wagner–Sillar model calculations for gas permeation, it was confirmed that IL immobilization transformed the diffusion mode of CO2 in the confined mass transfer channels of the MMMs from Knudsen diffusion to facilitated diffusion. However, the immobilization of excessive ILs in the mesopores blocked the mass transfer channels of the MMMs, resulting in lower gas permeability and decreased CO2 separation selectivity.

Low-cost, interdigitated capacitive sensor using laser-written graphene foam for touch, proximity, and liquid level detection

Flexible capacitive sensors are gaining popularity in place of sophisticated optical sensing or bulky mechanical designs for specific applications such as proximity/gesture detection and liquid level sensing. So, here, we propose Laser Induced Graphene Foam (LIGF) based planar capacitive sensors, which are flexible, highly sensitive, energy-efficient, and cost-effective, making them accessible for various applications. The working of these sensors involves the interdigitated planar electrode configuration and the fringing effect, influencing capacitance when the permittivity or the electric charge of the surrounding medium changes. LIGF planar capacitive elements were produced on a commercially availed polymer polyimide by using direct laser writing technique employing a low-cost diode laser. The developed LIGF-based planar capacitive touch sensor showed an average touch response (|ΔC/Co|) of more than 49%; moreover, when used for proximity sensing, this sensor could detect the presence of human hand up to a maximum distance of 170 mm from the sensor surface. An extended design of the sensor has demonstrated liquid level sensing with an accuracy of 0.97 mm. As a result of its ability to sense dielectric materials, contactless operation, long-range sensing, cost-effectiveness, low-power consumption, and environmental friendliness, the LIGF electrode-based capacitive sensor can be incorporated into a variety of modern technology and devices.