Flame‐Retardant Host–Guest Films for Efficient Thermal Management of Cryogenic Devices

Abstract

Phase change materials hold tremendous potential for thermal energy storage and temperature management due to their high latent heat and chemical stability. However, the manufacture of flame-retardant, form-stable phase change films working under a cryogenic environment remains difficult. Herein, an organic polydopamine-aramid nanofiber (PANF) aerogel film with a limiting oxygen index (LOI) of 32 is applied as a host to confine a unique phase change guest material (i.e., deep eutectic solvent, DES) to fabricate PANF-DES host-guest flame-retardant cryogenic phase change films. The PANF aerogel film is prepared through the in situ polymerization of dopamine within the aramid nanofiber hydrogel film, exhibiting a high specific surface area of 289 m 2 g −1 . The cryogenic phase change material is a ternary DES composed of ammonium chloride (NH 4 Cl), ethylene glycol (Eg), and deionized water (H 2 O). The as-prepared PANF-DES host-guest films with the phase transition temperature of −21 °C and melting enthalpy of 225 J g −1 can withstand fire for 60 s without naked flame, and the peak of heat release rate (pkHRR) is only 26.0 MJ kg −1 . This study opens the way for developing ultra-low flammable phase change composite films, as well as shows great potential applications for thermal management in cryogenic devices.

Bending Stiffness-Directed Fabricating of Kevlar Aerogel-Confined Organic Phase-Change Fibers

“…The enthalpy of the PW@H-KAF increased with the decreases of the concentration of the KNF dispersion, as well (Figure f). For the phase-change fiber prepared with 2.5 wt % KNF dispersion (PW@2.5%H-KAF), the enthalpy can go up to 172 J/g, which is higher than that other phase-change packaging materials reported previously (Figure g) − and much higher than commercial outlast fibers with enthalpy of about 3.72 J/g (Figure S10). It is worth mentioning that the enthalpy of PW@2.5%H-KAF (172 J/g) is higher than that of PW@2.5%KAF (167.8 J/g), which is attributed to the grafted alkanes enhancing the affinity between KNFs and paraffin wax (Figure S11).…”

“…TG curves (e) and DSC curves (f) of the Kevlar aerogel-confined paraffin fibers prepared with different concentration of KNF dispersion, at the concentration of 2.5, 8, and 10 wt % (PW@2.5%H-KAF, PW@8%H-KAF, and PW@10%H-KAF), respectively. (g) Comparison of thermal energy storage behaviors of our PW@H-KAF with those in literature. − (h) Temperature–time curves of 10 cycles test. (i) Stress–strain curves of the PW@2.5%H-KAF, PW@8%H-KAF, and PW@10%H-KAF.…”

Recent advances in fire‐retardant carbon‐based polymeric nanocomposites through fighting free radicals

“…Reproduced with permission. 113 Copyright 2021, Wiley VCH. (B) The synthesis routs of (B-i) DMA and ADMA monomers, and (B-ii) P(AN-co-DMA) copolymer.…”

“…(A) Schematic description of the PANF‐DES host‐guest film and its functionality: fabrication of (A‐i) PANF host film and (A‐ii) ternary DES guest, (A‐iii) thermal management and flame retarding performances of PANF‐DES host‐guest film. Reproduced with permission 113 . Copyright 2021, Wiley VCH.…”

Directional fabricating of flexible and compressible cellulose nanofibril composite aerogel with excellent thermal insulation, flame-retardancy and radiative cooling for efficient thermal management

“…In the past few years, aerogel has received tremendous attention and wide application in all walks of life. As a three-dimensional (3D) interconnected porous solid material, aerogel has many fascinating characteristics, such as low density, high porosity, large speci c surface area and low thermal conductivity (Hu et al 2020b; Xin et al 2021; Yang et al 2021b). This impels aerogel to serve as thermal insulation protecting layers for electronic devices and heat transfer inhibition llers for building walls to achieve human thermal comfort and sustainable energy development.…”