Phase Change Materials Microcapsules Research Articles

Double-layered phase change material microcapsules with enhanced solar thermal conversion performance and fire safety for buildings

Building energy saving is directly related to resource utilization optimization and residential comfort, which is important for the environment and production. At present, building energy saving is developing towards green, recyclable, and low-risk directions. Phase change materials, as effective energy storage materials, can pollution-freely regulate room temperature. Regarding the leakage, phase change materials are encapsulated into microcapsules. However, the flammability and slow thermal response of phase change material microcapsules hinder their application in building materials. Herein, novel double-layered phase change material microcapsules (D-MPCMs), with the inner poly melamine tetramethylene phosphonium sulfate (PMTMPS) shell layers and outer polydopamine (PDA) shell layers, are prepared by in-situ polymerization method, which are filled into epoxy resin (EP) coatings. This study is the first to use cross-linked flame retardants as the shells of microcapsules. The outer PDA shell layer improves the flame retardancy of microcapsules while overcoming the problem of slow thermal response rate. Thermogravimetric analysis and differential scanning calorimeter tests are considered to explore the thermal stabilities and properties of the resultant microcapsules. Results demonstrate that D-MPCMs have a residual mass of 10.8 % more at 600 ℃ and a faster thermal response rate. The study shows that the addition of the PDA shell layers not only reduces the total heat release from 64.29 MJ/m2 to 45.01 MJ/m2 but also enhances the solar thermal conversion performance which gives potential in the process solar energy storage design and fire safety design in actual building application of epoxy resin coatings.

1-Tetradecanol phase change material microcapsules coating on cotton fabric for enhanced thermoregulation

Rising climate change and extreme weather conditions underpin thermoregulation limitations of conventional textiles. This study investigates enhancing the thermal properties of cotton fabric by incorporating synthesized 1-tetradecanol (TD) phase change material (PCM) microcapsules. Characterization of the TD microcapsules was performed using dynamic light scattering (DLS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The microcapsules (average size of 0.49 μm) displayed a melting enthalpy (∆Hm) of 105 J·g−1 and a crystallization enthalpy (∆Hc) of 51 J·g−1. The microcapsules were mixed with the acrylic binder in three different ratios (75:25, 50:50, and 25:75). Hydrothermal, knife-over-roll, and pad-dry-cure methods were employed for coating microcapsules to cotton fabric. Microcapsule coating on cotton fabric using hydrothermal coating with a 75:25 microcapsule binder ratio achieved the highest add-on (55 %) and good durability after 25 home washes. The thermal insulation R-value of the coated fabric was enhanced (0.0029 m2 K·W−1) at 40 °C. The real-time test showed a temperature difference of 2.8 °C and thermal imaging displayed lower emissivity for TD-coated fabric. The TD microcapsule coating offers a promising method for developing climate-responsive textiles, enhancing thermal comfort, and reducing energy consumption in heating and cooling systems.

Development and thermophysical investigation of stable fatty alcohol/SiO2 phase change material microcapsules through interfacial polycondensation

Development and thermophysical investigation of stable fatty alcohol/SiO2 phase change material microcapsules through interfacial polycondensation

Photothermal phase change material microcapsules via cellulose nanocrystal and graphene oxide co-stabilized Pickering emulsion for solar and thermal energy storage

Photothermal phase change material microcapsules via cellulose nanocrystal and graphene oxide co-stabilized Pickering emulsion for solar and thermal energy storage

Double emulsion templates for efficient production of phase change microcapsules

The utilization of phase change materials (PCMs) in thermal storage technology exhibits great potential for various applications in thermal management and latent heat storage systems. However, leakage of organic PCMs hinders its practical application. Encapsulation of PCMs in microcapsules with polymer shells can prevent PCM leakage while improving heat transfer and stability. In this study, shell monomers were introduced as an immiscible third phase into the traditional o/w two-phase emulsion system, and the formed three-phase complex emulsion was dynamically reconfigured to exhibit a core–shell encapsulated conformation induced by interfacial tension, resulting in the formation of a thermodynamically stable double emulsion. Microcapsules with 1,6-hexanediol diacrylate (HDDA) shells were successfully prepared using this double emulsion as a template. The emulsion configuration is of significant advantage in promoting stable encapsulation of the phase change material in the shell material, resulting in fast and efficient encapsulation and improved utilization of the phase change material. Phase change microcapsules with different phase change temperatures were prepared and characterized using n-octadecane (C18), methyl stearate (Mes), n-eicosane (C20) and n-docosane (C22) as phase change materials, respectively. Results show that the prepared microcapsules are spherically integrated, with smooth surfaces and obvious core–shell structures, and the enthalpies of phase transition of C18, Mes, C20 and C22 microcapsules are as high as 171.86, 122.37, 165.77 and 178.69 J/g, respectively. These microcapsules exhibit excellent thermal stability and durability and the encapsulation efficiencies exceed 99.7 % at different phase change temperatures. Furthermore, the potential applications of PCM microcapsules in the field of temperature regulation were also demonstrated. This double-emulsion template method provides a straightforward, rapid and scalable approach for the mass production of microcapsules with different core–shell compositions.

Flame-retardant and phase-changing microcapsules incorporating black phosphorus for efficient solar energy storage

A novel phase change microcapsule has been developed and synthesized for solar energy storage systems. The fabrication process involved the in-situ polymerization of phase change microcapsules, wherein cellulose nanocrystals (CNCs) were employed as Pickering emulsifiers and nano-fillers to enhance the properties of the melamine formaldehyde resin (MF) shells. These enhancements included improved emulsifying ability, mechanical strength, and sustainability. Subsequently, black phosphorus (BP), a two-dimensional material with high solar absorption intensity and a wide frequency range, was covalently modified by MF to enhance the photothermal capacity of the microcapsules and reduce the thermal resistance between the photothermal material and the phase change material (PCM), this functionalized BP was referred to as MF@BP. The phase change microcapsules without and with MF@BP exhibit high latent heat values of 210.79 J g−1 and 207.92 J g−1, respectively. Furthermore, the PCM core content was measured at 88.9% and 88.5%, and the encapsulation rates are 99.0% and 98.8%, respectively. The PCM microcapsules with MF@BP demonstrated excellent photothermal characteristics with an efficiency of 92.04%. Additionally, the PCM microcapsules exhibit stability below 200 °C and retain 99.4% of their latent heat even after 100 cycles of heating and cooling. Furthermore, the PCM microcapsules display self-extinguishing properties due to the flame retardancy of the MF shell, and the incorporation of black phosphorus further enhanced the flame retardancy. Overall, these PCM microcapsules exhibit significant potential for utilization in solar energy systems.

Thermal conductive enhanced phase change composites with high latent-heat for constant temperature thermal management

Phase change materials (PCMs) can absorb and release heat without the temperature changing to realize the constant temperature thermal management. The low thermal conductivity (K) of PCM molecules leads to slow heat absorbing and releasing. In this study, a polyethylene glycol (PEG) based cross-linked polyurethane network is synthesized to wrap PCMs microcapsules. The composites have a high latent heat (152–164 J g−1) at 38 °C. Carbon fiber (CF) and Al powder with high K is composted to improve the thermal conductivity of the PCMs. After doping with CF, the K increases to two-fold to 0.306 W m−1 K−1. The experimental result reveals that the heat transfer inside the PCMs is improved obviously after doping with CF, which is further verified by a simulation result, and the composites show excellent shape stability and latent heat retention rate (>92 %) under 30 days' cycle test. This thermal conductivity enhanced PCMs composite is also formable which may have the potential applications for the thermal management of electronic devices, such as chips, fast charging, and battery.

The cores regulation of paraffin-chitosan phase change microcapsules for constant temperature building

Phase change materials (PCMs) can store and release latent heat under the designed phased change temperature and have received substantial interest for energy conservation and thermal control purposes. The use of PCMs in the construction of constant temperature buildings can improve the comfortable environment and save more energy. However, the leakage of PCMs during phase change process limits the application of PCMs. In this paper, a series of PCMs microcapsules with controllable core numbers is synthesized with paraffin (37 ℃) as the core and cross-linked chitosan as the wall. The single-core phase-change microcapsules (S−PCM) and multicore phase-change microcapsules (M−PCM) were prepared by adjusting the preparation condition. The latent heat of S−PCM and M−PCM are 61.4 mJ mg−1 and 50.1 mJ mg−1, respectively. The S-PCM and M−PCM display good stability without paraffin leakage. In addition, the composite blocks of gypsum and S−PCM (GSCM) and M−PCM (GMCM) were prepared and the thermoregulatory effection was investigated, where the surface temperature of GSCM was 5–10 ℃ lower than that of pure gypsum block. PCMs may also have broad application space in electronics, cold chain, and other industries.

Microencapsulation of phase change materials (PCMs) at low temperature using a novel thin film UV reactor

Phase-change materials (PCMs) have shown great promise for energy management in buildings and gained attention in the field of sustainable and energy-efficient construction. However, to fully utilize PCMs, their proper containment is vital. In this study, a photo-induced polymerization process using a new thin film UV reactor at room temperature for PCM microencapsulation in polymer shells of different acrylate-based monomers was investigated. Four different acrylate-based monomers were investigated: namely, methyl methacrylate (MMA), ethyl acrylate (EAA), butyl acrylate (BAA), and tert-butyl acrylate (TBMA). Commercial Rubitherm’s RT21 PCM (Tpeak,melting ∼ 21 °C and ΔH = 123 kJ/kg) and Irgacure® 819 as a photosensitive initiator were used. When MMA or EAA were used, scanning electron microscopy (SEM) images revealed smooth surfaces of PCM microcapsules (m-PCMs) with a hemispherical shape. While m-PCMs with rough surfaces, buckles, and dimples were found when BAA and TBMA were applied. The results showed that the highest levels of microencapsulation efficiency, yield, and PCM content were observed for MMA and EAA samples. The TBMA sample shows low values of microencapsulation efficiency and yield (about 29.1 and 53.4 %, respectively). Furthermore, results showed that adding cross-linking agents to the recipe has had multiple favourable effects. It has mitigated sub-cooling, increased PCM content, improved microencapsulation efficiency, and boosted the overall yield of PCM. In conclusion, the current work will contribute to the development of a microencapsulation technology of PCMs that overcomes the shortcomings of long time and high temperature needed in the present traditional microencapsulation procedure.

CEMENT COMPOSITES WITH THE ADDITION OF PHASE-CHANGE MATERIALS AS INNOVATIVE CONSTRUCTION MATERIALS FOR MAINTAINING A PLEASANT LIVING ENVIRONMENT

The aim of this work was to investigate the possibility of the addition of phase-change material (PCM) to mortar mixtures and its effect on the material’s mechanical and thermal properties. This work included the preparation of mortar mixtures with two different water-to-cement (w/c) ratios as well as various PCM volume-fraction additions. The main objectives were to determine the effect of the w/c ratio as well as the PCM addition on the mechanical properties of the mortars after (3, 7, and 28) d of curing. Additionally, we examined the microstructure of the prepared mortar composites and evaluated their thermal behaviour. Microstructural analysis revealed the uniform distribution of PCM microcapsules throughout the mortar matrix, which contributes to the efficient storage and release of thermal energy. Thermal properties were analysed by repeated heating and cooling cycles of the mortar composites. The repeatability of the cyclic testing results showed a reversible melting and solidification phase change of the PCM and indicated the potential use of such composites as an energy-efficient building material. The study highlighted the potential incorporation of the PCM into mortar mixtures to improve their thermal properties while maintaining the mechanical integrity. The research findings provide valuable insight into the development of sustainable building materials with greater energy efficiency and structural reliability.

Phase change material microcapsules doped with phosphorus-based flame retardant filled titanium dioxide nanotubes for enhancing the energy storage and temperature regulation performance of buildings

Solar energy is not only a green alternative to fossil energy but also a candidate for future mainstream energy sources. To improve the efficiency and application range of solar energy, we investigated tris (1-chloro-2-propyl) phosphate (TCPP) modified titanium dioxide nanotubes (TNTs) doped phase change material microcapsules (p-t-MPCMs) to enhance the temperature regulation and flame retardancy of epoxy resin (EP) coatings. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy determined the successful preparation of p-TNTs and p-t-MPCMs. Moreover, it was confirmed that the p-t-MPCMs had great thermal stability and reliability by the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The p-t-MPCMs increased residual mass by 12.2 % at 600 ℃ while correcting the initial melting temperature of MPCMs by 1.0 ℃. Based on the principle of oxygen consumption, the heat release rate (HRR) of EP coatings containing the p-t-MPCMs (p-t-MPCM/EP) was reduced from 665.92 kW/m2 to 443.78 kW/m2, resulting in a total heat release reduction (THR) of 17.73 % tested by a conical calorimeter. Then the results of the miniature chamber model demonstrated that p-t-MPCM/EP had outstanding temperature control ability. In summary, the p-t-MPCMs expressed great potential in regulating building temperature timely and improving the fire safety of EP coatings.

Thermo-Regulated Cotton: Enhanced Insulation through PVA Nanofiber-Coated PCM Microcapsules

The innovative integration of phase change materials (PCMs) into textiles through microencapsulation presents a transformative approach to developing thermally regulated fabrics. This study explores the synthesis and characterization of microcapsules containing a coconut oil core and an ethylcellulose shell, and their application on cotton fabrics coated with polyvinyl alcohol (PVA) nanofibers. The dual-layer system involving microcapsules and nanofibers is designed to enhance the thermal insulation properties of textiles by regulating heat through the absorption and release of thermal energy. The microencapsulation of PCMs allows for the effective incorporation of these materials into textiles without altering the fabric’s inherent properties. In this study, the coconut oil serves as the PCM, known for its suitable phase change temperature range, while ethylcellulose provides a robust shell, enhancing the microcapsules’ structural integrity. The application of a PVA nanofibers layer not only strengthens the thermal regulation properties but also protects the microcapsules from release while the fabric is manipulated, thereby prolonging the functional life of the fabric. Comprehensive testing, including scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), confirms the successful application and durability of the microcapsules on the textiles. Thermal imaging studies demonstrate the fabric’s enhanced capability to maintain a consistent temperature, highlighting the potential of this technology in applications ranging from smart clothing to energy-efficient building materials or automotive isolation. The integration of PCMs in textiles via microencapsulation and nanofiber technology marks a significant advancement in textile engineering, offering new opportunities for the development of smart and sustainable materials. The study demonstrates the promising potential of integrating PCMs into textiles using microencapsulation and nanofiber technologies. Despite the initially modest insulation improvements, the methodology provides a robust foundation for further research and development.

Study on the Interaction of Polymeric Chemical Additives with Phase Change Materials in Air Lime Renders.

The interaction of microencapsulated phase change materials (PCMs) with polymeric chemical additives in an air lime binding matrix was studied. These polymer-based additives included an adhesion booster (derived from starch) and a superplasticizer (polycarboxylate ether). Two different PCMs with melting points of 18 °C and 24 °C were assayed. The microcapsules were composed of melamine, with paraffin-based PCM cores. Measurements of zeta potential, particle size distribution, adsorption isotherms, and viscosity analyses were performed to comprehend the behavior of the polymer-based additives within the air lime matrix and their compatibility with PCMs. Zeta potential experiments pointed to the absence of a strong interaction between the lime particles and the microcapsules of PCMs. At the alkaline pH of the lime mortar, the negative charge resulting from the deprotonation of the melamine shell of the microcapsules was shielded by cations, yielding high positive zeta potential values and stable dispersions of lime with PCMs. The polycarboxylate ether demonstrated the ability to counteract the increase in mixing water demand caused by the PCM addition in the lime matrix. The dispersing action of the superplasticizer on the lime particles was seen to exert a collateral dispersion of the PCMs. Conversely, despite the positive values of zeta potential, the addition of the starch-based additive resulted in the formation of large PCM-lime clumps. Air lime renders incorporating 5, 10, and 20% PCMs by weight with various dosages of these chemical additives were experimented with until the optimal formulation for the specific application of the mortars as renderings was achieved. This fine-tuned formulation effectively tackled issues commonly associated with the addition of PCMs to mortars, such as poor adhesion, crack formation, and reduced fluidity.

Preparation and characterization of double-shell phase change material microcapsules with flame retardancy and temperature regulation capability as low-emission building fillers

The building application of phase change materials (PCMs) has attracted widespread attention due to energy conservation and emission reduction. In this study, designed and prepared by two-step polymerization poly melamine tetramethylene phosphonium sulfate (PMTMPS) coating the raw phase change materials microcapsules (MPCMs), which were novel double-shell microcapsules (D-MPCMs). D-MPCMs further achieved low smoke and low toxicity in the fire based on enhancing the temperature regulation performance of MPCMs. The chemical structure of D-MPCMs was characterized by Fourier transform infrared (FTIR) spectroscopy, and 13C solid-state nuclear magnetic resonance (NMR). Transmission electron microscope (TEM) confirmed that D-MPCMs were successfully prepared, whose shapes were regular spherical. The results of differential scanning calorimetry (DSC) showed that D-MPCMs revealed excellent phase transition enthalpy (80.51 J/g). Then, the resultant D-MPCMs had good thermal reliability and stability from the thermogravimetric analysis (TGA), characterized by a residual mass of D-MPCMs was 17 % more than that of MPCMs. In the cone calorimeter test (CCT), we confirmed that the coated PMTMPS significantly reduced the fire risk parameters of the rigid polyurethane foam (RPUF) containing D-MPCMs (D-MPCM/RPUF) referring to the heat release rate (HRR), total heat release (THR), and total smoke production (TSP). D-MPCM/RPUF exhibited the lowest peak values of HRR and TSP, which were 400.115 kW/m2 and 10.512 m2, respectively. In addition, the PMTMPS shell significantly enhanced the solar photo-thermal conversion performance of the D-MPCMs. To sum up, D-MPCMs have great potential to improve flame retardancy, environmental protection, and temperature regulation capability for building thermal insulation materials.

Analysis of the Thermal Stability of PCMs and Its Effect on Energy Storage Efficiency

The intermittent nature of many sources of clean energy has a considerable impact on energy conversion efficiency, making it a significant hurdle to the development of adequate power generation systems. The rapid advancement of thermal energy storage offers hope for a solution to this issue (TES). Applications that produce energy from renewable sources benefit from TES because it increases their efficiency and dispatchability. Phase Change Materials (PCMs) are becoming more and more popular for use in thermal energy storage (TES). Since they increase the heat transfer area and stop melted materials from escaping, microcapsules boost the thermal and mechanical performance of PCMs used to store thermal energy. The number of studies addressing the benefits of PCM microcapsules in energy systems has increased in recent years. This article provides a thorough analysis of PCM microcapsules for thermal energy storage. The five areas discussed here are PCM categorization, encapsulation shell materials, microencapsulation techniques, characterisation of PCM microcapsules, and thermal applications. Understanding PCM microcapsules and providing key concepts for using this technology for the storage of thermal energy in the future are the objectives of this analysis.

Preparation and characterization of phase change material microcapsules with carbon nanotubes loaded with Mg[sbnd]Al layered double hydroxides for controlling temperature in the building

Tubular structure embedding technique has promising applications in improving the thermal conductivity of phase change material microcapsules (PCMM). In this paper, the carbon nanotubes (CNT) were pretreated with flame retardant using magnesium‑aluminum layered double hydroxide (LDH) by co-precipitation method and then embedded in the shell of microcapsules. Thus, a phase change material microcapsule with both temperature control capability and flame retardancy was prepared. The microcapsules used capric acid (CA) as the core and polymethyl methacrylate (PMMA) as the shell, and the particle size was 100 nm-1 μm. The successful composition of the samples was verified by TEM and FT-IR. DSC test proves that CNT and LDH-modified CNT have very positive performance in improving the thermal conductivity of microcapsules. The outcome of TGA analysis and cone calorimeter test showed that the incorporation of modified PCMM into the rigid polyurethane foam (RPUF) matrix had a significant effect on improving its thermal stability and flame retardancy. The infrared thermal image analysis and self-created mini-chamber model were set up to characterize the temperature control performance of the sample. The results showed that the modified phase change material microcapsules have broad prospects in the field of building material temperature control.

Double-layered hydrogels based on phase change material and pen ink for continuous and efficient solar-driven seawater desalination

A novel double-layered hydrogel based on the polyacrylamide matrix, pen ink, and phase-change microcapsules was developed to construct a hydrogel-based evaporator for efficient and continuous seawater desalination. The n-eicosane (core)@crystalline TiO2 (shell) phase-change microcapsules were fabricated through interfacial polycondensation, and the resulting phase-change microcapsules obtained a considerably high latent-heat capacity of 187 J·g−1. The upper layer of the hydrogel exhibits a high solar absorptivity of over 90 % due to the introduction of pen ink as a solar absorber, which helps the hydrogel-based evaporator to gain an excellent photothermal energy conversion capability. A high evaporation efficiency of 93.89 % was obtained for the developed hydrogel-based evaporator along with a high evaporation rate of 1.85 kg·m−2·h−1 under one-sun illumination. The phase-change microcapsules dispersed in the lower layer of the hydrogel can act as a latent heat-storage unit to store a great quantity of photothermal energy through melting phase change by the phase change material core. This imparts a consecutive evaporation capability to the developed hydrogel-based evaporator. As a result, its water production was increased by 11 % under 50-min one-sun illumination and 50-min non-illumination.

A Dual Encapsulation Strategy for High-Temperature Micro PCM Particles with High Cyclic Durability.

Addressing critical issues such as high-temperature corrosion, leakage, degradation, and subpar cyclic performance is imperative for phase change materials (PCMs), prompting the development of appropriate encapsulation techniques to surmount these challenges. In this study, a dual encapsulation strategy is proposed for high-temperature micro PCM particles. Al-Si core is microencapsulated via the "solvent evaporation-heating curing" method. Subsequently, TiO2 is employed as the skeleton material for form-stable encapsulation of PCM microcapsules by "cold pressed sintering". Detailed analysis of the crystalline phase transformation mechanism in the sintering synthesis pathway of TiO2 underscore its potential as a robust structural material with exceptional thermal stability. Furthermore, the incorporation of hexagonal boron nitride (hBN) results in a substantial enhancement of the thermal conductivity of the composites, increasing by 121.1-131.3%. The prepared form-stable phase change microcapsules (FSPCMs) are subjected to 5000 thermal cycles in the air atmosphere. There is no observed PCM leakage or composite ruptures in the FSPCM. Moreover, the oxidized mass gain is merely 3.3%, signifying exceptional oxidation resistance. Thermophysical analysis indicates that FSPCM can retain 91.3% of the enthalpy after 2000 cycles, with over 80% preservation after 5000 cycles, underscoring its remarkable cyclic thermal durability.

Construction of ammonium polyphosphate-modified halloysite nanotubes on phase change material microcapsules for the enhancement of thermophysical performance and flame retardant properties

Organic microencapsulated phase change materials (MPCMs) are regarded as promising for building energy efficiency while the low thermal conductivity and flammability limit their further application. Aiming at improving the thermal response performance and flame retardancy of the MPCMs, the MPCMs embedded by ammonium polyphosphate-modified halloysite nanotubes (a-HNTs) are developed and then applied in the epoxy resin (EP) coatings. Herein, the ammonium polyphosphate (APP) is grafted onto HNTs as a flame retardant for the first time and the resultant nanotubes are successfully embedded into the shell of traditional MPCMs. As a result, the obtained microcapsules (a-MPCMs) possess a regular spherical morphology and the desired chemical composition. Moreover, the a-HNTs with their unique inorganic tubular structure connect the inside and outside of the original polymethylmethacrylate (PMMA) shell and act as the thermally conductive channel, which greatly facilitates the conversion of external heat to the latent heat of the capric acid (CA) core. The phase change data show that the embedding of a-HNTs has little effect on the encapsulation efficiency of MPCMs, and the latent heat of a-MPCMs is 118.3 J/g. Meanwhile, the a-HNTs/PMMA hybrid shell also significantly improves the thermal stability of MPCMs with the highest residual weight of 24.3%. With the addition of a-MPCMs, the resultant temperature-control coatings (a-MPCMs/EP) hold a high thermal cycle stability and excellent temperature control performance with less temperature fluctuation. In addition, a-HNTs also provide superior flame retardant properties for a-MPCMs/EP. Compared to the EP composites with the same mass fraction of pristine MPCMs added (MPCMs/EP), the pHRR and THR of a-MPCMs/EP are reduced by 30.2% and 4.5%, respectively. Through flame retardant modification of HNTs and incorporating them into the shell material of MPCMs, this work provides a promising approach to the development of multifunctional MPCMs with enhanced thermophysical performance and flame retardant properties.

Highly conductive and elastic multi-responsive phase change smart fiber and textile

Smart fiber, which can sense external environment changes intelligently and response quickly, has become an important building block to weave wearable system. Wet-spinning phase change materials (PCM) into smart fabrics offers great promise to regulate temperature and achieve personized thermal comfort in an intelligent way. However, the intrinsic low mechanical elasticity and stimuli responsiveness of PCM seriously blocking its application in wearable systems. In this work, we developed an ultra-stretchable PCM-based smart fiber for personal healthcare and thermal management, via wet-spinning PCM microcapsules embedded in elastic polyurethanes with dual responsive networks. Organic poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) “glued” inorganic carbon nanotubes/graphene skeleton into 3D hierarchically interconnected responsive and sensitive network along elastic fibers, which not only exhibits high sensitivity to multi stimuli (mechanical/electrical/thermal/light), but also facilitates efficient carrier transfer between PCM microcapsules for rapid response. Elastic PCM-based smart fiber with high mechanical stretchability (>200%) not only could adapt to the intense large movements seamlessly, but also convert these deformations into electrical signals for healthcare monitoring. Furthermore, the stretchable conductive PCM-based smart fiber(1.96×104 S/m) still remains robust stimuli-responsiveness with excellent Joule heating and photothermal effect even under large mechanical deformations, which could convert multi stimuli into latent thermal energy during response process and store it for self-powered personal thermal management. The robust PCM-based smart fiber with outstanding knotting capability can be woven into large-scale breathable textiles. The stretchable multi-responsive PCM-based fiber holds great potential in emerging wearable electronics and smart textiles.