Key Takeaways & Executive Findings
- •• • Achieves a low Curie temperature (Tc) of 35 °C, enabling precise thermal management near room temperature, with an ultralow initial resistivity (ρin) of 50 Ω cm, which reduces required heating voltage and enhances operational safety in precision electronics. • • Delivers a high PTC intensity (PTCI) of 7.0, defined as log(ρmax/ρin), ensuring rapid and sensitive current interruption for adaptive temperature control, surpassing previous benchmarks for low-Tc composites. • • Demonstrates exceptional cycling stability with >95% resistivity retention after 100 thermal cycles, and maintains performance after 14 days of space-environment exposure, validating reliability for aerospace applications. • • A self-regulating heater using this composite stabilizes an aluminum block at 30.6 ± 0.03 °C under 20 V in a −10 °C environment without external controls, proving practical viability for autonomous thermal management.
China Clean Energy & Battery Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
Polymer-based positive temperature coefficient (PTC) composites exhibit temperature-responsive resistivity, yet conventional systems with Curie temperatures (Tc) above 50 °C fail to meet the precision thermal management demands of room-temperature electronics. This study presents a ternary composite wherein carbon black (CB) is selectively localized within a myristyl alcohol (MA) phase, stabilized by an ethylene vinyl acetate (EVA) matrix. The reversible solid-liquid transition of MA dynamically disrupts and reconfigures CB conductive networks, while EVA elasticity suppresses phase migration at elevated temperatures. The optimized MA/EVA/CB composite achieves a low Tc of 35 °C, ultralow initial resistivity (ρin) of 50 Ω cm, high PTC intensity (PTCI = 7.0), and exceptional cycling stability with >95% resistivity retention after 100 thermal cycles. Even after 14 days of real space-environment exposure, the composite maintains ultralow resistivity and high PTCI. Differential scanning calorimetry and Fourier-transform infrared spectroscopy confirm molecular integrity under extreme conditions. Microstructural analysis reveals that MA melting/crystallization governs conductive network disruption and reconfiguration. A self-regulating heater fabricated from this composite stabilizes an aluminum block at 30.6 ± 0.03 °C under 20 V in a −10 °C environment without external control. These low-Tc PTC composites offer transformative potential for adaptive thermal management in aerospace electronics.
1. Introduction
Polymer-based positive temperature coefficient (PTC) composites, constructed from conductive fillers and insulating polymers, have demonstrated broad application prospects in intelligent temperature control due to their unique temperature-resistance response. The core mechanism involves precise regulation of the conductive percolation effect, enabling temperature-responsive on-off switching of current pathways. These composites are valuable in lithium battery thermal management, self-limiting heating devices, temperature sensors, and circuit overload protection. However, practical performance depends on synergistic optimization of four critical parameters: initial resistivity (ρin), PTC intensity (PTCI), Curie temperature (Tc), and thermal cycling stability. Conventional PTC composites with high Tc (>50 °C) are unsuitable for precision electronics requiring room-temperature operation, and low-Tc composites (Tc < 50 °C) face challenges in balancing electrical resistivity, stability, and sensitivity.
Recent advances have focused on multiscale structural engineering, yet a gap persists for low-Tc composites that simultaneously achieve ultralow resistivity, high PTC intensity, and robust cycling stability. This work addresses the bottleneck by engineering a ternary composite where carbon black (CB) is selectively dispersed in a myristyl alcohol (MA) phase, stabilized by an ethylene vinyl acetate (EVA) matrix. The reversible solid-liquid transition of MA dynamically modulates CB conductive networks, while EVA elasticity suppresses phase migration under thermal stress. The resulting MA/EVA/CB composite achieves a Tc of 35 °C, ρin of 50 Ω cm, PTCI of 7.0, and >95% resistivity retention after 100 cycles, withstanding 14 days of space-environment exposure. A self-regulating heater demonstrates stable operation at 30.6 ± 0.03 °C under 20 V in −10 °C environments, validating its potential for adaptive thermal management in aerospace electronics.
Loading authentic research manuscript (Pages 1–5)...
DONG Chang, LIU Huan-Huan, LI Teng, YANG Li, SONG Gui-Lin, XU Hui-Kang, LEI Jun, LI Jie, YAN Ding-Xiang, LI Zhong-Ming (2025). Dynamic Percolation Networks Engineered Low Curie Temperature PTC Composites for Self-Adaptive Thermal Management. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3526-5
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the failure mechanism under repeated thermal cycling, and how does the composite maintain >95% resistivity retention after 100 cycles?
The failure mechanism in conventional PTC composites involves irreversible phase migration and conductive network degradation. In this composite, the EVA matrix provides elasticity that suppresses MA phase migration during melting/crystallization cycles. Microstructural studies confirm that MA melting/crystallization reversibly disrupts and reconfigures CB networks without permanent damage. After 100 thermal cycles, the composite retains >95% of its initial resistivity, and DSC/FTIR analyses confirm molecular integrity, ensuring long-term reliability.
How does the cost and scalability of MA/EVA/CB composite compare to legacy PTC materials for commercial production?
The composite utilizes commercially available carbon black, myristyl alcohol, and ethylene vinyl acetate, which are low-cost commodity materials. The processing involves standard melt blending and compression molding, compatible with existing polymer processing lines. While precise cost parity data is not provided, the ultralow ρin of 50 Ω cm reduces material volume requirements for a given power output, potentially lowering overall device cost. Scalability is demonstrated by the fabrication of a self-regulating heater, indicating potential for mass production.
What are the operational limits of the self-regulating heater under extreme environmental conditions, such as space exposure?
The composite was exposed to real space-environment conditions for 14 days and retained ultralow resistivity and high PTC intensity (7.0). The heater stabilized an aluminum block at 30.6 ± 0.03 °C under 20 V in a −10 °C environment without external controls. These results indicate robust performance in extreme conditions, including vacuum, thermal cycling, and radiation, making it suitable for aerospace electronics. However, long-term degradation beyond 14 days and performance under higher voltages remain to be fully quantified.
How does the PTC intensity of 7.0 translate to response time and current interruption efficiency in practical circuits?
PTC intensity (PTCI) is defined as log(ρmax/ρin). A PTCI of 7.0 means the resistivity increases by a factor of 10^7 from initial to maximum, enabling rapid current interruption. This high sensitivity allows the composite to swiftly switch off current pathways upon reaching Tc, enhancing adaptive temperature control. In the self-regulating heater, this resulted in stable temperature regulation at 30.6 ± 0.03 °C, demonstrating precise and efficient thermal management.
What is the chemical stability of myristyl alcohol within the EVA matrix, and does it leach or degrade over time?
DSC and FTIR analyses confirm molecular integrity of the composite after thermal cycling and space exposure. The EVA matrix encapsulates the MA phase, preventing leaching. The reversible solid-liquid transition of MA is confined within the EVA network, and no chemical degradation of MA was observed. The composite maintained performance after 14 days in space environment, indicating excellent chemical stability. However, long-term stability beyond these tests and under continuous high-temperature operation requires further investigation.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.