电热相变水凝胶用于人体热管理

… Flexible electro-thermal responsive composite phase change materials (PCMs) hold broad … phase change hydrogel (PCH) PAM/Na₂HPO₄·7H₂O/PPy with excellent electro-thermal …

… This study proposes an innovative phase change hydrogel synthesized by the sol-gel … The unique combination of these components endows the hydrogel with leakage prevention, …

Flexible electrothermal composite phase change materials (PCMs) are promising candidates for portable thermotherapy. However, a great challenge remains to achieve high PCM loading while maintaining reasonable flexibility. Herein, the polypyrrole-decorated melamine foam (PPy@MF) was fabricated and thereafter applied to confine binary PCM mixtures composed of a high-enthalpy long-chain polyethylene glycol (PEG4000) and its short-chain homologue (PEG200) to make the novel PPy@MF-PEG4000+200 composite PCM. At a high loading of up to 74.1% PEG4000 and a high latent heat energy storage density of 150.1 J/g, the composite PCM remained flexible at temperature (-20 °C) far below its phase transition point thanks to the plasticine effect of PEG200. The composite also demonstrated good Joule heating performance, providing fast heating from 28 to 70 °C at low applied voltages (4.5-6.0 V). The energy could be stored efficiently and released to maintain the composites at the proper temperature. The electrothermal performance of the composite remained undisturbed during curved or repeated bending, showing good potential to be used for personal thermal management and thermotherapy.

… It makes PEG/GF@PPy exhibit an effective electro-thermal … Finally, the composite PCM with photoelectric/electrical heat … composite PCM with high photo/electro-thermal conversion …

… within 25 minutes to achieve strong phase change buffering. Uniquely, the system … planar electrical enhancements at -20 C (2.37 to 7.64 S·m -1 ). In terms of thermo-responsive electrical …

… /electrical responsive phase change materials … phase change hydrogels, which were composed of hydrated salts (sodium sulfate decahydrate, SSD) and polyacrylamide (PAM) hydrogel …

Ion-conductive hydrogels have received great attention due to their significant potential in flexible electronics. However, achieving hydrogels that simultaneously possess high ionic conductivity and stability under varying humidity conditions remains a challenge, limiting their practical applications. Herein, we propose a thermally controlled chemical cross-linking strategy to prepare an elastic and conductive hydrogel (ECH) of poly(vinyl alcohol) (PVA) with high content of H2SO4. The covalent cross-links formed effectively tackle the instability issue in high humidity of physically cross-linked PVA/H2SO4 hydrogels with high ionic conductivity, which were previously developed via the polymer-in-salt strategy. We systematically investigated the reaction conditions and clarified the methods to optimize the hydroxyl dehydration of PVA, resulting in excellent mechanical properties and ion conductivity simultaneously. The ECH demonstrates impressive ionic conductivity (up to 392 ± 49 mS cm-1) and elasticity (over 80% resilience upon stretching and compression after being equilibrated at various humidity levels for 24 days). Thanks to the excellent water retention of the high H2SO4 content, the ECH maintains an ionic conductivity exceeding 210 mS cm-1 for over 420 days at 50% relative humidity (RH) and retains over 100 mS cm-1 even after 3 days under extremely dry conditions (7% RH). These remarkable properties make the ECH an ideal candidate for applications requiring reliable ionic conductivity in diverse environmental conditions. Additionally, we demonstrated that the ECH can function as a stretchable Joule heater with high conformability for heating up objects with curved surfaces. The heating rate could reach a fast rate of ∼12 °C s-1 even when a human-safe alternating current voltage is below 36 V, attributed to the high ionic conductivity. We believe that the high performance and ease of fabrication make our hydrogels a promising candidate for use as electrolytes in flexible energy storage devices, electrolyte gates in electrochemical transistors, and artificial skin, which often face long-term stability challenges under varying humidity conditions.

… Temperatures achieved by Joule heating for different samples as a function of applied voltage (a), homogeneity of Joule heating for different samples (b), thermographs of samples at …

… Additionally, the Janus film exhibited good Joule heating performance. Overall, the prepared (B/A)-(C/A) Janus film showed promising prospects in lightweight, flexible and …

… A novel hydrogel-based hygroscopic material, consisting of PVA-PA-LiCl, is developed and … The hydrogel achieves a high power density of 3.48 μW/cm 2 and reduces the device …

HYPOTHESIS Phase change materials (PCMs) based on inorganic hydrated salt has garnered considerable attention for their high energy storage density, non-toxicity, cost-effectiveness. However, conventional techniques mainly address the macroscopic deficiencies of their phase change performance, with limited focus on precise manufacturing and customized functionalities at microscale. EXPERIMENTS Herein, we propose an innovative concept of microencapsulated phase change hydrogels (MPCHs), synthesized through electro-coalescence in a feasible droplet-based microfluidic platform. A comprehensive analysis is conducted on the influence of hydrated salt and hydrogel concentrations, as well as electric and flow conditions. FINDINGS We achieve the precise manipulation of the merging dynamics over a wide range of hydrated salt and hydrogel concentrations under AC electric field. The three-dimensional network structure and hydrophilicity of hydrogels helps to reduce supercooling, minimize phase separation, improve the cyclic performance. The versatile fluidic configuration allows for on-demand control over different mechanical and phase change properties in realistic scenarios. MPCHs could not only be applied as a thermal interface material for flexible electronics but also functions as a microscale thermal modulator for temperature buffering in bacterial cultivation. The unique transparency allows them to be carriers for temperature-sensitive fluorescent dyes, enabling simultaneous temperature detection and analysis. This approach offers a new approach to improve the thermal performance of hydrated salt PCMs and broaden the application ranges via droplet microfluidics.

… (2) applying conductive materials during the processes (such as sol-gel, coating, … /phase change material/conductive material) is proposed in this paper. In this structure, the conductive …

The utilization and transformation of heat have played pivotal roles in numerous significant stages of human societal evolution and advancement. Recently, more rigorous and precise requirements have been imposed on thermal functional materials for applications including microelectronic device cooling, personal thermal regulation in extreme environments, green building initiatives, flexible wearable electronics, and solar thermal collection. Thermal functional fibers offer advantages such as lightweight construction, versatile functional design, and integrated manufacturing capabilities. By modifying the composition, structure, and fabrication techniques of fibers, control over heat transfer, storage, and conversion processes can be optimized. This review underscores the latest developments in thermal functional fibers, emphasizing high thermal conductivity fibers, thermal insulation fibers, thermal radiation regulation fibers, phase-change thermal storage fibers, thermoelectric fibers, Joule heating fibers, photothermal conversion fibers, thermally actuated fibers, and multifunctional composite fibers. It elucidates how these various fibers enhance thermal performance through innovative material selection, fabrication methods, and structural design. Finally, the review discusses prevailing developmental trends, current challenges, and future directions in the design and fabrication of thermal functional fibers.