High Phase Change Enthalpy Enabled by Nanocellulose Enhanced Shape Stable Boron Nitride Aerogel
Liqiang Wan, Chao Liu, Daxian Cao, Xiao Sun, Hongli Zhu
Abstract
In this work, we developed an in situ one-step, scalable, high-yield (98.2%) method for the preparation and surface functionalization of boron nitride nanosheets (BNNSs) with amino and carboxyl groups by ball milling l-glutamine and hexagonal boron nitride. The obtained l-glutamine-grafted BNNSs (BNNSs-g) can be well-dispersed in water at concentrations above 30 mg/mL, which is a value that falls on the high end of the reported literature. The functionalized BNNSs were further cross-linked with hydroxyl-rich cellulose nanofibers (CNF) in a low concentration to form a durable and porous aerogel. This aerogel was then applied as a 3D skeleton for the polyethylene glycol (PEG) phase change materials (PCMs) used for thermal storage. These BNNSs-g/PEG-based PCMs have a high phase change enthalpy of 150.1 J/g (reaching ∼ 94% that of pure PEG), as well as high thermal diffusivity. The highest thermal diffusivity (0.148 mm2/s) is about 4.5 times higher than that of a pure PEG. In addition, the BNNSs-g/CNF/PEG-based PCMs have excellent shape stability, facilitating the broad application of BNNSs composite materials.