Transition Temperature Research Articles

Innovative Fluorinated Polyimides with Superior Thermal, Mechanical, and Dielectric Properties for Advanced Soft Electronics

This study addresses the limitations of traditional polyimides (PIs) in high-frequency and high-temperature soft electronic applications, and then introducing trifluoromethylbenzene (TFMB) into the molecular structure and employing various diamines as connecting components to solve the bottleneck. The innovative molecular design enhances thermal, mechanical, and dielectric properties, overcoming challenges in balancing these performances. The optimized fluorinated PI (TPPI50) exhibits exceptional properties, including a glass transition temperature of 402 °C, thermal decomposition temperature of 563 °C, tensile strength of 232.73 MPa, elongation at break of 26.26%, and dielectric constant of 2.312 at 1 MHz with a dielectric loss as low as 0.00676. These improvements are attributed to the unique synergy between TFMB’s fluorinated groups, which reduce molecular polarization, and the biphenyl structure, which reinforces chain stability. Compared to conventional PIs, TPPI50 demonstrates superior comprehensive performance, making it highly suitable for soft circuits, high-frequency signal transmission, and advanced applications such as wearable devices and biosensors. This study provides a robust framework for industrial applications, offering a path to next-generation soft electronics with enhanced reliability and performance.

Greater Influence of Density on the Electrical Properties of an Organic Semiconductor Glass Compared to Molecular Orientation.

Physical vapor deposition is widely used in the fabrication of organic light-emitting diodes and has the potential to adjust the density and orientation through substrate temperature control, which may lead to enhanced electrical performance. However, it is unclear whether this enhanced property is because of the horizontal molecular orientation or the increased density. The effects of the density and orientation on the electrical properties of a potential electron transport material, (3-dibenzo[c,h]acridin-7-yl)phenyl)diphenylphosphine oxide (TPPO-dibenzacridine), were investigated. According to the gyration tensor analysis, TPPO-dibenzacridine resembled an oblate ellipsoid. Furthermore, these films exhibited the highest density when prepared at a substrate temperature of 87.5% of the glass transition temperature with an increase in density of approximately 1.5%. Variable angle spectroscopic ellipsometry measurements confirmed that the transition dipole moment direction of the dibenzacridine moiety, which is involved in the electrical properties, remained isotropic at this temperature. Although horizontal orientations are known to optimize their π-π overlap and improve the electrical properties, the lowest driving voltage was observed under these conditions, which led to the conclusion that the enhanced electrical properties of TPPO-dibenzacridine are greatly influenced by the increased density rather than by the molecular orientation.

Conserved charge susceptibilities in the relativistic mean-field hadron resonance gas model: Constraints on hadronic repulsive interactions

In this paper, we investigate the effect of repulsive interaction between hadrons on the susceptibilities of conserved charges, namely baryon number (B), electric charge (Q) and strangeness (S). We estimate second-, fourth- and sixth-order susceptibilities of conserved charges, their differences, ratios and correlations within ambit of mean-field hadron resonance gas (MFHRG) model. We consider repulsive mean-field interaction among meson pairs, baryon pairs and antibaryon pairs separately and constrain them by confronting the results of various susceptibilities with the recent lattice quantum chromodynamics (LQCD) data. We find that the repulsive interactions between baryon–baryon pairs and antibaryon–antibaryon pairs are sufficient to describe the baryon susceptibilities of hadronic matter at temperatures below QCD transition temperature. However, small but finite mesonic repulsive interaction is needed to describe electric charge and strangeness susceptibilities. We finally conclude that the repulsive interaction between hadrons play a very important role in describing the thermodynamic properties of hadronic matter, especially near the quark–hadron phase transition temperature ([Formula: see text]). The mean-field parameter for baryons ([Formula: see text]) should be constrained in the range [Formula: see text] to get a good agreement of baryon susceptibilities with the LQCD results, whereas meson mean-field parameter [Formula: see text] must be included with [Formula: see text] to get a reasonable agreement of MFHRG model with the LQCD results for electric charge and strangeness susceptibilities.

Examining the mechanical and biodegradable characteristics of hemp fiber added PLA bio-composites with various modifications

In this research, green composites were produced by reinforcing 30% hemp fiber by weight for the purpose of improving the properties of polylactic acid (PLA) polymer. Surface treatments such as alkali (NaOH) and silane (APTES), different modification methods such as poly (butylene succinate) (PBS) and thermoplastic polyurethane (TPU) blend processes, maleic anhydride (MA) coupling were all employed to improve fiber-matrix interfacial adhesion. Extrusion and injection molding were used to create PLA bio-composites, and their thermal, mechanical, and degrading characteristics were examined. The glass transition and crystallization temperature generally reduced, while the melting temperature and degree of crystallinity increased, according to Differential Scanning Calorimetry (DSC). Reinforcement of hemp fiber increased the tensile strength of all bio-composites. Compared to pure PLA, the tensile strength of N-H/PLA (alkali-treated hemp/PLA) is 54.3%, P-H/PLA (PBS-untreated hemp/PLA) is 24.69% improved the T-H/PLA (TPU-untreated hemp/PLA) had the best elongation at break value due to the TPU polymer’s flexibility. The N-H/PLA bio-composite showed the lowest soil degradability after neat PLA. The S-H/PLA (silane-treated hemp/PLA) offers the highest weight loss value. The FTIR spectra of APTES-treated hemp fibers did not change significantly. The N-H/PLA had the lowest water absorption, while the M-H/PLA (MA- untreated hemp/PLA) had the greatest.

Impact of Polymer Physicochemical Features on the Amorphization and Crystallization of Citric Acid in Solid Dispersions

The amorphization and crystallization of citric acid in the presence of a variety of polymers were investigated. Polymers were chosen for their different physicochemical features, including hygroscopicity, glass transition temperature (Tg), and functional groups capable of forming intermolecular non-covalent interactions with citric acid. Citric acid solutions with varying amounts of pectin (PEC), guar gum (GG), κ-carrageenan (KG), gelatin (GEL), (hydroxypropyl)methylcellulose (HPMC), and carboxymethylcellulose sodium (CMC-Na) were lyophilized. Dispersions were stored for up to 6 months in controlled temperature and relative humidity environments and periodically monitored using powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Moisture sorption isotherms and moisture contents were determined. Amorphous solid dispersions of citric acid were successfully formed in the presence of ≥20% w/w CMC-Na and PEC or ≥30% w/w of the other polymers except KG which required a minimum of 40% polymer. All samples remained amorphous even in their rubbery state at 0% RH (25 °C and 40 °C), but increasing the RH to 32% RH resulted in citric acid crystallization in the KG dispersions, and further increasing to 54% RH resulted in crystallization in all samples. Polymer effectiveness for inhibiting citric acid crystallization was CMC-Na > PEC ≥ GEL > HPMC > GG > KG. To create and maintain amorphous citric acid, polymer traits in order of effectiveness were as follows: greater propensity for intermolecular non-covalent interactions (both ionic and hydrogen bonding) with the citric acid, carbonyl groups, higher Tg, and then lower hygroscopicity.

Enhancing the performance of polyfarnesene-based bio-rubbers with surface-modified cellulose nanocrystals and nanofibers

As the rubber industry seeks sustainable alternatives to mitigate its environmental impact, this study introduces a biobased approach using polyfarnesene rubber reinforced with plasma-modified cellulose nanocrystals (MCNC) and nanofibers (MCNF). The nanocellulose was modified by plasma-induced polymerization using trans-β-farnesene and was characterized by FTIR, XPS, XRD, TGA, and SEM to confirm the grafting of farnesene-derived polymer chains onto the cellulose surface, demonstrating the successful modification and integration of the nanoparticles. Polyfarnesene bio-based rubbers were synthesized through two different polymerization techniques: solution-based coordination polymerization (PFA1) and emulsion-based free radical polymerization (PFA2). The modified nanoparticles were incorporated into these rubber matrices at 2–12 wt% and vulcanized by incorporation of sulfur. The performance of bio-rubbers reinforced with cellulose nanoparticles was analyzed by tensile test and dynamic mechanical analysis (DMA). Mechanical tests focused on tensile strength, Young’s modulus, and elongation at break showed that incorporation of 12 wt% modified MCNF into the PFA1 and PFA2 increased tensile strength by 56% and 22%, and Young’s modulus by 27% and 58%, respectively (compared to the neat rubber matrix), while elongation at break decreased with increasing MCNF content. The addition of MCNC into PFA1 and PFA2 improved the deformation resistance values of 205% for PFA1-MCNC12% and 49% for PFA2-MCNC12%. Dynamic mechanical analysis showed an increase in storage modulus and a shift towards higher glass transition temperatures, indicating stronger filler-matrix interactions. The results demonstrate that plasma-modified cellulose nanoparticles effectively enhance the mechanical properties of polyfarnesene bio-rubbers, offering a sustainable alternative with performance competitive to synthetic rubbers.

Synthesis and optical properties of monomers and polymers with high refractive indexes based on piperidone thioacetals

AbstractA series of dithioazaspiroacrylamide monomers containing sulfur atoms in the cyclic structure and having high refractive indices have been synthesized. Transparent polymer films were obtained from these monomers. The refractive indices of monomers and polymers obtained from them were measured ( = 1.52–1.67) and their Abbe numbers were also measured (VD = 26–55). The glass transition temperatures of polymers were measured Tg = 45–155°C. Polymers consisting of spirocyclic unbranched units showed the highest refractive indices and high transparency, which seems promising for use in photolithography, holography, elements of polymer, and waveguide optics.Highlights From 4‐piperidone, dithioazaspiroacrylae monomers was obtained. Transparent polymer films with high refractive indices are obtained. Polymer with spirocyclic units showed high refractive index and Abbe number.

Preparation and Characterizations of Intrinsically Black Polyesterimide Films with Good Thermal Endurance at Elevated Temperatures for Potential Two-Layer Flexible Copper Clad Laminate Applications

Polymer films with combined properties of good thermoplasticity, good electrical properties, and good thermal endurance are highly required for two-layer flexible copper clad laminate (FCCL) applications. Meanwhile, the black appearance is also required for specific FCCL applications. Therefore, in the present work, a series of ester-linked polyimide (PEsI) films were designed and developed via the copolymerization chemistry of an ester-containing dianhydride of biphenyl dibenzoate-3,3′,4,4′-tetracarboxylic acid dianhydride (BPTME), a rigid-rod dianhydride of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA), an ester-bridged diamine of 2-(4-aminobenzoate)-5-aminobiphenyl (ABABP), and a functional diamine of 4,4′-iminodianiline (NDA). The molar proportion of the BPTME/BPDA was fixed to be 20:80 and that of ABABP/NDA increased from 50:50 for PEsI-1 to 0:100 for PEsI-VI. The afforded PEsI films showed obviously enhanced blackness with the increasing molar ratio of NDA in the polymers. The PEsI-VI film exhibited the optical transmittance values of 0 and 27.4% at the wavelength of 500 nm (T500) and 760 nm (T760), respectively. The values were apparently lower than those of the standard PI-ref produced from common pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) (T500 = 63.2%; T760 = 86.3%). Meanwhile, the PEsI-V film showed good blackness with the CIE Lab optical parameters of 1.83 for L*, 11.46 for a*, 3.13 for b*, and 0 for haze. The PEsI samples exhibited good thermoplasticity and the storage and loss modulus of the films rapidly decreased around the glass transition temperatures (Tg) in the dynamic mechanical analysis (DMA) tests. The PEsI samples revealed the Tg values from 247.2 °C to 286.1 °C in the differential scanning calorimetry (DSC) measurements. The PEsI samples exhibited the linear coefficients of thermal expansion (CTE) of (27.1~33.4) × 10−6/K from 50 to 250 °C, which was comparable to that of the PI-ref sample (CTE = 29.5 × 10−6/K), however, a bit higher than that of the copper foil (CTE = 17.0 × 10−6/K).

Thermal activation and dynamic mechanical characterization of glass-reinforced shape memory polymer composites for medical applications

Thermally activated shape memory polymers are of increasing interest nowadays. Their incorporation in textile-based preforms reinforced composites is being focused on, owing to some functional applications of medical textiles, e.g., posture support of joints after fracture surgery where gradual healing of fractures requires the joints to be moved slightly, which is not possible with conventional supports. Hence, this study was aimed at the development and characterization of thermally activated shape memory composites having woven glass fiber reinforcements for such applications. Three different stackings or laminates were developed (single-, double-, and triple-layered composites), solely using glass fiber, whereas resin material induced shape memory function. The glass transition temperature of the engineered specimens was determined, and the shape memory function was evaluated at three different temperatures, namely, below, at, and above the glass transition temperature (45°C, 65°C, and 85°C). Increasing the characterization temperature decreased the shape recovery time by 75%, owing to softening and better polymer chain mobility at higher temperatures. The shape recovery velocity also increased with increasing temperature. Increasing the number of glass fabric layers compromised the shape memory function; however, the interlaminar shear strength was improved.

Statistical Characteristic of the Transition Temperature Shift for Reactor Pressure Vessel Steel

Abstract In the ductile?brittle transition temperature range, the Charpy absorbed energy exhibits an inherent variation, which causes uncertainty in the transition temperature shift. In the current codes for the evaluation of fracture toughness of reactor pressure vessel steels, margins are considered to account for the uncertainty in the transition temperature shift. Although they have been statistically determined, their adequacy is only inductively assured by specific surveillance program databases. In this study, a model was proposed to describe the statistical characteristics of the transition temperature shift. An equation to describe the standard deviation of the associated transition temperature was theoretically derived from a previously proposed variation model of the Charpy absorbed energy according to the law of propagation of uncertainty. The obtained standard deviations were then compiled into procedures to estimate the transition temperature shift according to the sufficiency of the parameters required for the evaluation (shape of Charpy curve and sample size). The standard deviations of the transition temperature shift assumed in past studies/present codes were compared with those predicted using the proposed model. In the range of upper shelf energy greater than 100 J, the standard deviations in past studies/present codes.

The spin-wave energy spectrum and transition temperature of the two-dimensional VSe2-like: a retarded Green’s function method study

Based on the recent discovery of intrinsic magnetism in monolayer films VSe2, we have constructed a two-dimensional (2D) Heisenberg model incorporating the 1Tand 2Hstructures. These configurations consist of three layers: the upper and lower surface layers and a middle layer. Using the retarded Green's function method, we investigate the spin-wave energy spectrum, spin-wave density of states, and transition temperature of the system. It is found that in the 2Hstructure, the spin-wave energy spectrum of the system exhibits three direct energy gaps, with one branch being independent of the wave vector. Further analysis shows that at this constant energy, a particular surface state emerges in the 2Hstructure. In contrast, the spin-wave energy spectrum in the 1Tstructure features only two energy gaps-one direct energy gap1 and one indirect energy gap3-without forming a unique surface state. Single-ion anisotropy and interlayer interactions between the upper and lower surface layers influence the energy gaps in the spin-wave energy spectrum and the system's transition temperature. This theoretical work sheds light on forming particular surface states in monolayer 2Hstructure magnetic materials. It provides crucial theoretical support for designing and fabricating next-generation low-dimensional magnetic random-access memory.

Interaction Analysis between Cationic Lipid and Oligonucleotide with a Lipid Membrane-Immobilized Monolith Silica Column: A High-Performance Liquid Chromatography Approach.

Understanding the interactions between lipid membranes and nucleotide drugs is crucial for nucleic acid therapy. Although several methods have been employed to evaluate nucleotide-lipid membrane interactions, these interactions can be complex; this complexity arises from how external factors, such as ionic strength or temperature, influence the lipid membrane's overall properties. In this study, we prepared a lipid membrane-immobilized monolithic silica (LMiMS) column for high-performance liquid chromatography (HPLC) analysis to understand interactions between the lipid membrane and nucleic acid. First, the Raman shift, zeta potential, fluidity, and polarity of the LMiMS-column membrane were analyzed and compared to dispersed liposomes (not immobilized) with the same lipid composition. The results indicated that the column can effectively imitate the temperature-dependent properties of the lipid membrane, suggesting that the immobilized lipid membrane can be used as a model of dispersed liposomal membranes. Subsequently, HPLC was performed to analyze the interaction between the lipid membrane and oligonucleotides. The retention factor k was determined as an interaction factor between the LMiMS column and nucleic acid models (poly 10, 25, and 50mer dC) at various temperatures and mobile phase salt concentrations. The results revealed that changes in membrane interaction were significant by the phase state and salt concentration. Further analysis of the retention factor k showed that the interaction is weak below the phase transition temperature but strong above the phase transition temperature. The results indicate that membrane properties (rigidity and polarity) are also related to membrane interaction, which can be evaluated with the LMiMS column. This analytical method can provide a new perspective on estimating the interactions between target molecules and the lipid membrane through their temperature-induced dynamics. From these results, our method could be useful for analyzing lipid membrane-oligonucleotide interactions.

Exploring Lifshitz Transition and Superconductivity in 3R-NbS2 under Pressure

Abstract The interplay among electronic topological phase transitions and superconductivity in the field of condensed matter physics has consistently captivated researchers. Here we have succeeded in modulating the Lifshitz transition by pressure and realized superconductivity. At 25.7 GPa, superconductivity with a transition temperature of 1.9 K has been observed in 3R-NbS2. The Hall coefficient changes from negative to positive at 14 GPa indicating a Lifshitz transition in 3R-NbS2, and the carrier concentration continues to increase with pressure. X-ray diffraction results indicate that the appearance of superconductivity is not attributable to structural transitions. Based on theoretical calculations, the emergence of new band is attributed to a Lifshitz transition and the new band coincide with the Fermi surface at a pressure of 30 GPa. These findings provide new insights into the relationship between the Lifshitz transition and superconductivity.

Roberge-Weiss periodicity and singularity in a hadron resonance gas model with excluded volume effects

Quantum chromodynamics (QCD) with pure imaginary baryon number chemical potential μ=iθT, where T is temperature and θ is a real number, has the Roberge-Weiss periodicity. We study the θ-dependence of the baryon number density and the pressure in the hadron resonance gas model with excluded volume effects of baryons. It is shown that the baryon number density and the pressure are smooth periodic functions of θ at low or high temperature. However, they have singular behavior at θ=(2k+1)π where k is an integer, when T∼211 MeV. This temperature is consistent with the Roberge-Weiss transition temperature TRW obtained by lattice QCD simulations. This singularity can be explained by the dual excluded volume effects in which the roles of pointlike and nonpointlike particles are exchanged each other in the ordinary excluded volume effects. It is also indicated that the excluded volume effect is visible just below TRW and is directly detectable by the lattice QCD simulation at finite θ. We compare the results with the one obtained by the Polyakov-loop extended Nambu–Jona-Lasinio model. Published by the American Physical Society 2025

Limonene as biobased building block for functional monoterpene acrylate monomers

Abstract Limonene, a widely used natural raw material, provides an excellent basis for the synthesis of functional acrylate monomers. The presence of two double bonds in this monoterpene enables a twofold functionalization, enhancing its versatility for various chemical modifications. By incorporating an acrylate functionality, the polymerization potential of this terpene is significantly increased, allowing for the production of polymers with high conversion rates. The introduction of additional functional groups also makes the synthesized polymers suitable for applications requiring subsequent crosslinking or specialized material properties. Besides the mono- and bifunctional acrylate monomers, variants with additional hydroxyl and epoxide groups were synthesized. These considerably extend the versatility and application possibilities of the compounds. As proof of concept, free radical polymerization of the monomers was demonstrated in this work, and the reaction was determined by differential scanning calorimetry. The resulting polymers exhibit glass transition temperatures between 83 and 96°C, making them suitable for use in, e.g., coating systems.

Nanocomposites of Epoxy with Fe3O4 Featuring Dynamic Disulfide Bonds: Fracture Toughness, Reprocessing, and Functional Properties.

Nanocomposites of epoxy with Fe3O4 featuring dynamic disulfide bonds were fabricated. To facilitate the dispersion of Fe3O4 nanoparticles, we synthesized poly(ε-caprolactone)-grafted Fe3O4 nanoparticles, which were then incorporated into epoxy to generate robust interfacial interactions between epoxy and the inorganic nanoparticles. Through this approach, a fine dispersion of the inorganic nanoparticles in the epoxy matrix was successfully obtained. The incorporation of Fe3O4 nanoparticles with fine dispersion resulted in the epoxy being effectively toughened; the critical stress field intensity factor (KIC) was enhanced twice as the control epoxy. Thanks to the integration of the dynamic covalent bonds (i.e., disulfide bonds), the nanocomposites displayed excellent reprocessable or recyclable properties. Depending on the contents of poly(ε-caprolactone)-grafted Fe3O4 nanoparticles, the nanocomposites can be modulated to have shape recovery with the desired shape transition temperatures. Benefiting from the dynamicity of disulfide bonds, the shape memory behavior featured reconfigurability. Inheriting from the nature of Fe3O4 nanoparticles, the nanocomposites likewise displayed superparamagnetic and photothermal properties. By taking advantage of the photothermal behavior, shape memory can be triggered through infrared laser irradiation and in a noncontact manner.

Emergent p-Wave Superconductivity in a Dual Topological Insulator BiSe via Superconducting Proximity Effect.

The quest for anisotropic superconductors has been a long-standing pursuit due to their potential applications in quantum computing. In this regard, experimentally, d-wave and anisotropic s-wave superconducting order parameters are predominantly observed, while p-wave superconductors remain largely elusive. Achieving p-wave superconductivity in topological phases is highly desirable, as it is considered suitable for creating topologically protected qubits. To achieve topological superconductivity in the dual topological insulator BiSe, we place an s-wave superconductor NbSe2 in its close proximity employing the van der Waals epitaxy technique. Low-temperature differential conductance measurements performed at the heterojunction exhibit a dual-dip feature with a V-shaped inner dip, a characteristic of p-wave superconductivity. This observation is corroborated by the multiband 2D Blonder-Tinkham-Klapwijk (BTK) fitting, where the inner and outer gaps exhibit p-wave and s-wave character, respectively. Furthermore, the BTK analysis reveals that the two superconducting gaps experience distinct effective critical fields and transition temperatures.

Fully 4D-Printed Near-Infrared-Actuated Lab-on-Valve Solid-Phase Extraction Devices.

Four-dimensional printing (4DP) technologies can expand the functionality of stimuli-responsive devices to enable the integration of multiple stimuli-responsive parts into a compact device. Herein, we used digital light processing three-dimensional printing technique, flexible photocurable resins, and photocurable resins of the temperature-responsive hydrogels comprising N-isopropylacrylamide (NIPAM), N,N'-methylenebis(acrylamide) (MBA), and graphene for 4DP of a lab-on-valve (LOV) solid-phase extraction (SPE) device. This device featured flow manifolds and a monolithic packing connected by four near-infrared (NIR)-actuated temperature-responsive switching valves composed of a poly(NIPAM/MBA) (PNM) ball pushing a flexible membrane. NIR irradiation caused the deswelling of the PNM ball [temperature > volume phase transition temperature (VPTT) of the hydrogel], and the valve was opened to switch the flow direction. The termination of this irradiation caused the swelling of the PNM ball (temperature < VPTT of the hydrogel) to close the valve and thus recover the original flow direction to achieve the automatic NIR-actuated fluid control. The optimized 4D-printed NIR-actuated LOV-SPE device enabled a fully automatic SPE scheme coupled with inductively coupled plasma mass spectrometry for the determination of Mn, Co, Ni, Cu, Zn, Cd, and Pb ions (detection limits = 0.1,6.8 ng L-1). The reliability of this analytical method was validated by determining the metal ions in the four reference materials (CASS-6, SLRS-5, 1643f, and Trace Elements Urine L-2) and environmental water and human urine samples. Our results demonstrated the capability and applicability of 4DP technologies for advancing the automation of LOV-SPE schemes and related analytical methods.

Linear Dielectric Polymers with Ferroelectric-Like Crystals for High-Temperature Capacitive Energy Storage.

Achieving optimal capacitive energy storage performance necessitates the integration of high energy storage density, typical of ferroelectric dielectrics, with the low polarization loss associated with linear dielectrics. However, combining these characteristics in a single dielectric material is challenging due to the inherent contradictions between the spontaneous polarization of ferroelectric dielectrics and the adaptability of linear dielectrics to changes in the electric field. To address this issue, a linear isotactic sulfonylated polynorbornene dielectric characterized by ferroelectric-like crystals has been developed. The sulfonyl dipoles in the ferroelectric-like crystals are oriented in the same direction, thereby enabling this polymer to exhibit a considerable dielectric constant (7.5) at room temperature. Notably, when the operating temperature surpasses the polymer's glass transition temperature (Tg ≈ 140 °C), its dielectric constant rises to 12 with just minor changes in the dissipation factor. At 150 °C, 90% efficiency of the discharge energy density reaches as high as 6.76 Jcm-1 under a low electric field of 320 MV m-1, which is ten times that of the state-of-the-art, high-temperature, capacitor-grade polyetherimide. The enhancement of high-temperature capacitive performance, achieved by utilizing the crystallinity of isotactic polymers to form a polar structure, presents a new perspective for the design of high-temperature dielectric polymers.

Proton Exchange Membrane with Dual-Active-Center Surpasses the Conventional Temperature Limitations of Fuel Cells.

High temperature-proton exchange membrane fuel cells (HT-PEMFC) call for ionomers with low humidity dependence and elevated-temperature resistance. Traditional perfluorosulfonic acid (PFSA) ionomers encounter challenges in meeting these stringent requirements. Herein, this study reports a perfluoroimide multi-acid (PFMA) ionomer with dual active centers achieved through the incorporation of sulfonimide and phosphonic acid groups into the side chain. The fluorocarbon skeleton and multi-acid side chain structure facilitate the segregation of hydrophilic and hydrophobic microphases, augmenting the short-range ordering of hydrophilic nanodomains. Furthermore, the introduction of a rigid segment-benzene ring is employed to decrease side chain flexibility and raise the glass transition temperature. Notably, the prepared membrane exhibits a conductivity of 41 mS cm-1 at 40% relative humidity, showcasing a 1.8 times improvement over that of PFSA. Additionally, the power output of the H2-air fuel cell based on this membrane reaches 1.5W cm-2 at 105°C, marking a substantial 2.3 times enhancement compared to the PFSA. This work demonstrates the unique advantages of perfluorinated ionomers with multiple protogenic groups in the development of high-performance high-temperature electrolyte materials.