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Phase change materials (PCMs) with remarkable latent heat storage/release capacity have demonstrated prominent advantages in energy conservation and efficient thermal management. Nevertheless, simultaneously achieving high thermal energy storage capacity, excellent toughness, and flexibility in PCMs is a significant challenge for programmable deformations when used in complex environmental scenarios. A flexible PCM is reported with programmable deformation constructed through a three‐dimensional (3D) dynamic cross‐linked network. This approach has culminated in the development of homogeneously cross‐linked and self‐supporting polyurethane‐based solid‐solid PCM with graphene enhancement, which exhibits exceptional properties of high latent heat storage/release capacity (∆Hm = 105.3 J g−1, ∆Hc = 105.0 J g−1), high toughness (ε = 1543%, σ = 19.2 MPa), excellent flexibility, and shape memory behavior (Rr = 90.3%). Notably, when subjected to photothermal stimulation, it can lift objects weighing more than 2620 times their weight, presenting a working density of 1330 kJ m−3. This flexible PCM, which simultaneously possesses a high latent capacity and photothermal‐driven performance, opens a new pathway for artificial muscles or soft robots with the requirements for energy conservation and thermal management in complex scenarios. [ABSTRACT FROM AUTHOR]

In this study, a series of reversible thermochromic microencapsulated phase change materials (TC-MPCMs), exhibiting excellent thermal energy storage performance, were designed and fabricated successfully. The core of TC-MPCMs was comprised of crystal violet lactone employed as thermochromic colorant, bisphenol A as developer and 1-tetradecanol as co-solvent, respectively. The effects of shell materials on reversible thermochromic properties, thermal performance and thermal stability of TC-MPCMs were investigated systematically as well. These influencing factors of encapsulation process such as the dripping speeds, SMA emulsifier and pH were carried out to optimize the encapsulation parameters. Additionally, the TC-MPCMs modified with fabricated silver nano-particles displayed excellent thermal properties, heat transfer and antibacterial activity. Both the microscopic morphology and microstructure of TC-MPCMs were characterized and discussed systematically. The thermal distribution on the TC-MPCMs was exhibited via the infrared camera. The performance of fusion, crystallization, enthalpy and thermal stability of various capsules were measured and studied as well. In the end, ultraviolet–visible spectrophotometry was employed to investigate the antibacterial activity of Ag-TC-MPCMs(B). Furthermore, the TC-MPCMs(B) and Ag-TC-MPCMs(B) exhibited excellent thermal stability and the cyclic durability. [ABSTRACT FROM AUTHOR]

In this study, a series of reversible thermochromic microencapsulated phase change materials (TC-MPCMs), exhibiting excellent latent heat storage-release performance, were designed and fabricated successfully. The characterization and microstructure regulation of TC-MPCMs were conducted systematically as well. The core of TC-MPCMs was comprised of crystal violet lactone employed as thermochromic colorant, bisphenol A employed as developer and 1-tetradecanol employed as co-solvent, respectively. These influencing factors of encapsulation process such as the amount of emulsifier, stirring rate, feeding weight of core/shell ratio, acid resistance and thermal cyclic durability were carried out to clarify the effect of various experimental conditions. The surface morphology, shell thickness and core–shell structure of TC-MPCMs were characterized via optical microscope (OM), thermal field emission scanning electronic microscope (TFE-SEM), transmission electron microscope (TEM), respectively. From different scanning calorimetry (DSC) analysis, the performance of temperature of fusion and crystallization and enthalpy of TC-MPCMs under various conditions were measured as well. The results of thermogravimetric (TG) analysis illustrated the influence on thermal stability of TC-MPCMs. In addition, Lab color space obtained by colorimeter is certainly intuitive to observe the colorimetric characteristics of TC-MPCMs as well. More importantly, the reversible thermochromic property associated with phase state of the 1-tetradecanol could also provide a visual evidence of energy storage or release performance of the TC-MPCMs. Furthermore, The TC-MPCMs exhibited excellent stability even after 100th thermal cycling test without any obvious performance degradation, including the morphology, phase change properties and thermal stability. In the end, the fire fighter protective clothing containing TC-MPCMs was designed and fabricated, which could provide adequate thermal protection in the various fire environments. Thus, TC-MPCMs developed in this work showed great potential applications in thermal protective clothing and other thermal regulation fields. [ABSTRACT FROM AUTHOR]

The aim of the paper was to enhance the mechanical properties and anti-permeability performance of microcapsules through shell modification to keep complete and stable structure during the manufacturing process. The effect of PVA adding dosage, modified methods and types of PVA on the performance of microcapsules was discussed in detail. When the PVA/MF ratio (0.04–0.25) was appropriate, the supercooling degree of microcapsules was reduced and thermal stability was improved to some extent. Furthermore, the modified method of adding PVA-1788 into microcapsules after curing probably formed the second protective encapsulation for RTPCMs, which contributed to obtaining MicroRTPCMs-2 with excellent mechanical properties and anti-permeability performance. Compared among the effects of various types of PVA modification on the performance of MicroRTPCMs, PVA with larger polymerization degree and higher alcoholysis degree can form modified resin with larger crosslinking degree, which was beneficial to generating more stable composite shell structure. Therefore, MicroRTPCMs1-2699 presented more outstanding mechanical properties and anti-permeability performance, satisfactory cycle stability and long-term reliability, as well as reversible thermochromic coloration and leakage-prevention performance. In the end, the main characteristic of RTPCMs was to in-situ observe the heat absorption, energy storage and heat release process of PCM cores, which would be great significance for the practical application of MicroRTPCMs in the fields of thermoregulated fibers, thermal energy storage textiles, heat energy transfers and energy-saving building materials. PVA modified MF MicroRTPCMs for thermal energy storage. Image 1 • PVA modified shell reduced supercooling degree of MicroRTPCMs. • The suitable PVA/MF ratios (0.04–0.25) contributed to improving performance of MicroRTPCMs. • PVA-2699 modification can form more stable composite shell structure. • MicroRTPCMs1-2699 exhibited outstanding mechanical properties and anti-permeability performance. • MicroRTPCMs1-2699 possessed thermal cyclic durability and reversible thermochromic performance. [ABSTRACT FROM AUTHOR]

• RT-MPCMs display excellent stable light-to-thermal conversion capability (η = 86.9%). • Black RT-MPCMs have absorbing visible light capability and release latent heat simultaneously. • RT-MPCMs can effectively store/release the latent energy and real-time color-monitoring. • The change in crystallization and color via temperature induction was explored in detail. • The intelligent adjustment-based garment presented excellent thermo-regulated properties. In this study, a series of reversible thermochromic MicroPCMs (RT-MPCMs) were synthetized through encapsulating ternary thermochromic mixtures via in-situ polymerization, and presented outstanding stable light-to-thermal conversion capability (η = 86.9%), excellent latent thermal energy storage-release performance (ΔH m = 171.9 J·g−1, ΔH c = 171.4 J·g−1) and color-changing monitoring the states of energy storage or release, satisfactory thermal reliability and thermal cyclic durability. The RT-MPCMs with spherical integrity, smooth surface morphology and obvious core-shell microstructure were obtained by emulsifying with the solution (1.2 wt%–3.1 wt%) of sodium salt of styrene maleic anhydride copolymer. The crystallization of RT-MPCMs was mainly affected by the structure of methyl stearate (MeS). The crystallization changes and coloration inside capsules was observed real-timely via microscope at different temperature ranging from 1 to 40 °C. In addition, based on these excellent performances, the actual application value of RT-MPCMs was further discussed. The narrow-disperse composite macrocapsules containing RT-MPCMs was prepared and further encapsulated by real non-woven fabrics substrate for the intelligent adjustment-based garment to research practical value in thermoregulation field. The experimental results show that it can absorb the latent thermal energy from the skin or environmental heat, which is beneficial for keeping constant and comfortable body surface temperature, and showing great application value in the fields of temperature regulation and thermal management. [ABSTRACT FROM AUTHOR]

Hydrophobic reversible thermochromic MicroPCMs with amino resins shell. • The effect of TDI modification on performance of TC-MPCMs was discussed in detail. • HTC-MPCMs possess hydrophobic surface (WCA = 148.5°). • HTC-MPCMs possess excellent latent heat storage capability and cyclic durability. The microstructure and composition of shell of reversible thermochromic microcapsulated phase change materials (TC-MPCMs) are crucial for their performance. High reaction activity between isocyanate group of TDI and active hydrogen of hydroxymethyl amino resin is conducive for TC-MPCMs to obtaining hydrophobic performance. Thus, a new type of TC-MPCMs with hydrophobic amino resins shell is developed via surface modifying using the prefabricated MF resin-encapsulated TC-PCMs as template. The experimental results shown the water contact angles (WCA) of the surface of modified microcapsules increased from 0° to 148.5°, suggesting that shell surface turned hydrophobic. The TC-MPCMs with hydrophobicity possessed good thermal properties (△H m = 100.0 J·g−1, △H c = 100.2 J·g−1), thermal stability, satisfactory thermal cyclic durability and reversible thermochromic performance. That might be beneficial for broadening its practical application value in the field of latent thermal energy storage. [ABSTRACT FROM AUTHOR]

Aiming at the characteristics of melamine-formadehyde resin with poor toughness and high brittleness owing to its unique structure of trizine ring, long-chain alkanol etherified melamine-formaldehyde prepolymer was selected as shell material to synthesize MicroPCMs. The study mainly explored the effect of etherification and relevant influencing factors in the etherification process on performance of microcapsules. Through a series of characterization, the alkyl chain of dodecanol can be grafted into the methylolated melamine-formaldehyde prepolymer via etherification, contributing to enhancing the adsorption of core material and encapsulation effect of microcapsules. The optimal molar ratio of melamine, formaldehyde and n-dodecanol was 1:7:2 in etherification process. N-dodecanol-etherified melamine-formaldehyde prepolymer was synthesized via one-step method as shell material for encapsulation n-dodecanol to obtain MicroPCMs4-2. The MicroPCMs4-2 finally obtained presented complete microstructure, uniform particle size distribution, well dispersibility and satisfactory thermal energy storage performance with high enthalpy value (△H m = 166.1 J/g, △H c = 160.2 J/g) and effective loading (72.2%) for potential applications to thermal-regulating textiles and energy storage fibers. Image 1 • Long-chain alkanol successfully etherified MF resin via one-step method. • Etherification contributed to improve the encapsulation efficiency of microcapsules. • The long-chain alkanol for etherification can be consistent with core materials. • MicroPCMs4-2 had perfect energy storage performance and mechanical properties. [ABSTRACT FROM AUTHOR]