Long-Term Autonomic Thermoregulating Fabrics Based on Microencapsulated Phase Change Materials

Janus cotton with unidirectional-wicking, tri-mold cooling and antibacterial performance for personal thermal-moisture management

Single-mode personal thermal-moisture management fabrics cannot ensure the comfort and safety of the human body in high-temperature, high-humidity, and complex environments. Here, a tri-cooling cotton fabric (TCCF) that combines evaporation, convection, and heat storage with a converging pore array, Janus wetting structure and phase change microcapsule is demonstrated. Benefiting from its Janus wetting structure and converging pore array, the TCCF exhibits excellent unidirectional sweat-wicking performance (717 unidirectional transfer index) and rapid water vapor transmission (223.0 g/m2/h). The TCCF can lower the temperature by 4.5 °C through evaporation and convection compared with conventional cotton. Furthermore, the TCCF demonstrates excellent buffering capacity for sudden temperature changes. Evaporation, convection, and heat storage help cool the human body in complex environments.

Ultrafast Thermal Conduction of Phase Change Fiber Enabled by Sheath Confinement-Induced Ordered Orientation of Hydroxylated BNNs

Phase change fibers (PCFs) are increasingly popular in thermal storage and release applications, such as temperature management. However, a simple but effective integration of thermal conductive materials into PCFs to deliver ultrafast thermal conduction remains a big challenge. Herein, a facile one-pot coaxial wet spinning strategy based on sheath-confinement-induced orientation arrangement of hydroxylated boron nitride nanosheets (BNNs-OH) is proposed to fabricate the high-performance PCFs. For the core-sheath PCFs, the cellulose nanofiber (CNF)-reinforced paraffin (CNF/PW) emulsions serve as the phase change core, while the dissolved cellulose and well-dispersed BNNs-OH act as the sheath precursor. By increasing the extrusion speed of the liquid core, the contraction of the fiber sheath is gradually finalized to induce the alignment of BNNs-OH based on the confinement effect. Consequently, the highly oriented BNNs-OH nanosheets in fiber sheath (f = 0.8) endow PCFs with high phase transition enthalpy (125.1 J g-1), excellent thermal conductivity (10.15 W m-1K-1), rapid heat transfer rate (1.6 cm s-1); moreover, the as-prepared PCFs show good tensile strength (11.21 MPa) and leakage-proof (0.13%). The as-prepared PCFs are combined with thermochromic dyes for functional fabrics or applied as thermal management for a phone, demonstrating excellent thermal conduction and heat dissipation.

The structural and key technological analysis of phase-change cooling garments

The frequent occurrence of extreme high-temperature climates poses severe threats to human health and safety. Personal cooling garments, as an effective means to alleviate heat stress among outdoor workers, have garnered significant attention domestically and internationally. Phase-change cooling garments (PCCGs) have gained popularity due to their cost-effectiveness, portability, environmental benefits and energy efficiency. However, PCCGs face limitations, e.g., short cooling duration, low thermal conductivity of phase-change materials (PCMs) and challenges in regulating phase transition temperature. This study reviews the evolution of cooling garments, examines the design and implementation of PCCGs, and discusses key technologies in their development. Future research is needed to explore novel PCMs, heat transfer models, garment design and intelligent temperature control. The goal is to create standardized, portable and comfortable PCCGs. Furthermore, commercial applications of PCCGs are expanding, highlighting their growing importance in improving occupational safety and ergonomics in high-temperature environments.

Phase-Changeable Metafabric Enables Dynamic Subambient Humidity and Thermal Regulation

A promising approach to prevent heat- and cold-related illnesses is the integration of zero-energy input control technology into personal thermal management (PTM) systems while reducing energy consumption. However, achieving optimal wearing comfort while maintaining subambient metabolic temperatures using thermally regulating materials without an energy supply remains challenging. In this study, we provide a simple and reliable methodology to produce a phase-changeable metafabric made of thermoplastic polyurethane and phase change capsule (PCC) particles with high moisture permeability and thermal comfort. This approach skillfully incorporates spray-formed PCC particles into a three-dimensional nanofibrous aggregate, forming a stable self-entangled network structure in a single step through simultaneous humidity-assisted electrospraying and electrospinning processes. Additionally, the metafabric demonstrates prominent water resistance and superhydrophobicity, which are attributed to the integration of PCC particles and nanofibers, resulting in the formation of a microporous/nanoporous structure resembling the surface of a lotus leaf. As a result, the phase-changeable metafabric shows an active and passive thermal control performance, with a water vapor transmittance rate of 13.1 kg m-2 d-1 and a phase change enthalpy of 115.05 J g-1 even after 100 thermal cycles. Furthermore, it displays excellent waterproofing capability, characterized by a water contact angle of 158.7° and the ability to withstand a high hydrostatic pressure of 87 kPa. In addition, the metafabric exhibits a good mechanical performance, boasting a tensile strength of 10.5 MPa. Overall, the proposed economical metafabric is an exemplary candidate material for next-generation PTM systems.

Fibrous Structures: An Overview of Their Responsiveness to External Stimuli towards Intended Application

In recent decades, the interest in responsive fibrous structures has surged, propelling them into diverse applications: from wearable textiles that adapt to their surroundings, to filtration membranes dynamically altering selectivity, these structures showcase remarkable versatility. Various stimuli, including temperature, light, pH, electricity, and chemical compounds, can serve as triggers to unleash physical or chemical changes in response. Processing methodologies such as weaving or knitting using responsive yarns, electrospinning, as well as coating procedures, enable the integration of responsive materials into fibrous structures. They can respond to these stimuli, and comprise shape memory materials, temperature-responsive polymers, chromic materials, phase change materials, photothermal materials, among others. The resulting effects can manifest in a variety of ways, from pore adjustments and altered permeability to shape changing, color changing, and thermal regulation. This review aims to explore the realm of fibrous structures, delving into their responsiveness to external stimuli, with a focus on temperature, light, and pH.

Photo-modulated activation of organic bases enabling microencapsulation and on-demand reactivity

A method is developed for facile encapsulation of reactive organic bases with potential application for autonomous damage detection and self-healing polymers. Highly reactive chemicals such as bases and acids are challenging to encapsulate by traditional oil-water emulsion techniques due to unfavorable physical and chemical interactions. In this work, reactivity of the bases is temporarily masked with photo-removable protecting groups, and the resulting inactive payloads are encapsulated via an in situ emulsion-templated interfacial polymerization method. The encapsulated payloads are then activated to restore the organic bases via photo irradiation, either before or after being released from the core-shell carriers. The efficacy of the photo-activated capsules is demonstrated by a damage-triggered, pH-induced color change in polymeric coatings and by recovery of adhesive strength of a damaged interface. Given the wide range of potential photo-deprotection chemistries, this encapsulation scheme provides a simple but powerful method for storage and targeted delivery of a broad variety of reactive chemicals, promoting design of diverse autonomous functionalities in polymeric materials.

Phase-Tailoring Wx V1-x O2 Meta-Nanofiber Enables Temperature-Editing Energy Control

Room-temperature phase change materials (RTPCMs) exhibit promise to address challenges in thermal energy storage and release, greatly aiding in numerous domains of human existence and productivity. The conventional RTPCMs undergo inevitable volume expansion, structural collapse, and diffusion of active ingredients while maintaining desirable phase change enthalpy and ideal phase change temperature. Here, a sol-gel 1D-induced growth approach is presented to fabricate meta nanofibers (Meta-NFs) comprised of vanadium dioxide with monoclinic crystal structure, and further achieve the editable phase change temperature from 68 to 37 °C through W-doping, which allowed for tailored length variation of the zigzag V-V bond. Subsequently, Meta-NFs are assembled into 3D aerogels with self-standing architecture, thereby enabling the independent use of the RTPCMs. The obtained metamaterials demonstrate not only the temperature-editing solid-solid phase transition, but also the stiffness of the ceramic matrix, exhibiting the thermal energy control capability at room temperature (37 °C), thermal insulation properties, temperature resistance, and flame retardancy. The effective creation of these fascinating metamaterials might offer new insights for next-generation and self-standing solid-solid RTPCMs.

Fabrications, Classifications, and Environmental Impact of PCM-Incorporated Textiles: Current State and Future Outlook

Phase change materials (PCMs) are an extraordinary family of compounds that can store and release thermal energy during phase changes. In recent years, the incorporation of PCMs into textiles has attracted considerable interest, since it represents a unique way to improve the comfort and usefulness of textiles. This article examines the advancements achieved in the preparation, classifications, and environmental effects of PCM-integrated textiles, along with a roadmap for the future. Progress of different PCM has been reported including its pros and cons. In addition, fabrications of the PCM on the apparel have been highlighted. Moreover, this Review analyzed the positive environmental impact of PCM-integrated textiles including improved insulation, extended product lifespan, and energy savings along with negative effects like higher energy consumption in the manufacturing process, added chemical additives tending to have a negative impact on the environment, less disposal features textiles and many more with recent references. Moreover, the future outlook also reports more research on nanoencapsulation, making it energy efficient, ensuring affordability, and more applications in smart PCM textiles. It seeks to stimulate additional research, encourage innovation, and contribute to the creation of high-performance, energy-efficient textiles by investigating the possibilities of PCM-enhanced textiles. The future of PCM in textiles is hopeful, with continuous research and technological advances resolving the aforementioned difficulties.