Electrothermal Phase Change Composite with Flexibility over a Wide Temperature Range for Wearable Thermotherapy.

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.

A Nature-Inspired Monolithic Integrated Cellulose Aerogel-Based Evaporator for Efficient Solar Desalination.

Solar-driven seawater desalination is a prospective approach to tackle the problem of freshwater shortage. Establishing a robust, efficient solar-thermal water evaporator with great salt-resistance through a facile and scalable fabrication technique is still a challenge. In this study, a floatable and robust monolithic integrated cellulose aerogel-based evaporator (MiCAE) with high performance is fabricated by carefully designing and integrating three functional components, namely, a hydrophilic cellulose-PVA aerogel (CPA), hydrophobic silylated cellulose aerogel (SCA), and multiwalled carbon nanotube (MCNT) coating layer (CPA@CNT), through the heterogeneous mixing and freeze-drying aerogel fabrication step in situ. Inspired by woods and mushrooms, the incorporation of SCA with mushroom-shaped CPA possessing wood-like structures in MiCAE can realize heat localization and effectively suppress irreversible heat dissipation. Meanwhile, CPA endows the evaporator with the rapid water transportation and great salt excretion capability because of its low-tortuosity porous structure. Thanks to the synergistic effect of the integrated functional structures, in the highly concentrated brine (17.5 wt %), the MiCAE can still realize the combination of high efficiency and obvious salt-resistance behavior. This work offers a facile, efficient salt-resistance solution for seawater desalination.