Janus Membrane Decorated by MXene Multilayered Nanoflakes for Wet–Thermal Management

Abstract

Personal wet–thermal management, which focuses on adjusting the moisture and temperature in a “human skin–wearable fabric–external environment” microclimate system, is the basis for ensuring the comfort of human beings and has recently attracted tremendous attention owing to its substantial significant role not only in ameliorating the health conditions but also in smart textiles for personal protection, electronic wearable devices, health monitoring, and so on. However, wearable fabrics focusing on personal comfort, especially wet–thermal dual-mode management, viz., including both efficient sweat removal and heat retention performances that provide protection for outdoor sports or work in a cold environment, still present huge challenges in their design, fabrication, and practical application. A Janus membrane with asymmetric wettability (superhydrophobic/hydrophobic–superhydrophilic/hydrophilic) along the thickness direction shows a unique directional water transport capacity, acts as a “water transport diode”, and is expected to be helpful to expel sweat/moisture efficiently from the human body to the external environment. Herein, we fabricated a hydrophobic/hydrophilic Janus membrane decorated by MXene (Ti3C2T x ) multilayered nanoflakes with outstanding photothermal conversion capacity via facile electrospinning combined with in situ polymerization. By virtue of asymmetric wettability and directional wicking, water and moisture can be driven from the hydrophobic layer to the hydrophilic layer, providing the Janus membrane with excellent directional water and moisture transport capacity. Furthermore, the successful decoration of MXene multilayered nanoflakes imparts electrical-power-independent heat retention capacity to the Janus membrane, resulting from the excellent photothermal conversion capacity of MXene. This work provides an insight into the facile design of Janus membranes for wet–thermal management and establishes a promising strategy not only to maintain personal comfort to ameliorate the health conditions as well as to improve the work efficiency of outdoor laborers in a cold environment but also to guarantee the special functions of smart wearable and multifunctional fabrics.

A Janus membrane doped with carbon nanotubes for wet–thermal management

“…Hence, liquid could be transported from one side to the other side unidirectionally but was blocked from the reverse side. [49][50][51] Such a unique capacity for unidirectional liquid transport endows a great potential to expel sweat/moisture from human skin efficiently. 52 Nonetheless, different Janus membranes have different layouts for hydrophobic/hydrophilic combination.…”

Designing Janus Two-Dimensional Porous Materials for Unidirectional Transport: Principles, Applications, and Challenges

“…Meanwhile, the photothermal layer can realize thermal insulation and prevent hypothermia. Some groups applied the photothermal Janus fabrics for either directional wicking or heat retention, which allows sweat to be transported from the hydrophobic gauze to the external environment easily or provides the possibility to maintain a consistent and optimal body temperature even in cold environments. ,, …”

“…By leveraging this process, Janus 2D porous materials have found wide applications in collecting dispersed oil (e.g., emulsions) and water (e.g., fog). On the other hand, there has been a growing interest in human wet-thermal management, and these intelligent Janus fabrics can transport sweat from the inner hydrophobic side to the outer hydrophilic side, maintaining dry and comfortable skin. − Since the driving forces of unidirectional transport in Janus 2D porous materials arise from their asymmetric structure or properties, this does not require additional energy input. The unidirectional transport characteristic of Janus materials can also find applications in energy conservation and emission reduction, such as in building dehumidification …”

Graphene Oxide Nanopowder-Based Hydrophobic Fluid Diode Fabric with Passive Radiative Warming for Simultaneous Thermal and Moisture Management during Cold Weather

“…The other way is to reduce the sweat residue on both the skin and the fabric, thereby reducing the amount of heat lost by evaporation. To reduce the sweat residue on the skin, materials with directional moisture transport properties (namely, fluid diodes) that combine hydrophilic and hydrophobic sections (Janus materials), as well as all-hydrophilic materials, have been proposed and implemented to transfer sweat from the skin side to the outer side of the fabric. − These materials can provide a degree of dryness to the individual, but sweat is still present at the hydrophilic layer and evaporation of the residual sweat consumes body heat, which decreases the warming capability of the fabric. , Few studies have reported sweat residue reduction in both the skin and the fabric. Unlike a liquid diode with a hydrophilic layer, a new kind of liquid diode fabric made entirely of all-hydrophobic materials was previously reported by the authors .…”