3D printing of customized lignocellulose nanofibril aerogels for efficient thermal insulation

Thermal insulation aerogel holds great promise in the transportation, storage, and use of temperature-sensitive electronic components under different environmental conditions. Due to their low density, high thermal stability, superior UV resistance, and low thermal conductivity, lignocellulose nanofibrils (LCNFs) aerogels meet the thermal insulation needs perfectly. However, the preparation of LCNFs aerogels with customizable size and high precision remains challenging. Herein, we report the following: (1) the preparation of LCNFs with tunable physicochemical properties from unbleached poplar pulp through the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and ultrasonication approach, and (2) the 3D printing of customized thermal insulation materials using LCNFs as viscoelastic gelatinous inks. In addition to the chlorine-free bleaching merit, the LCNF inks exhibit much lower yield stress compared to cellulose nanofibrils (CNFs) inks, thereby facilitating the smooth extrusion of filament under a much lower printing pressure. Furthermore, the residual lignin endows LCNFs aerogels with superior moisture tolerance, mechanical protection, UV resistance, and thermal insulation performance for temperature sensitive electronic components such as chips and batteries. This work opens a promising avenue for the rapid manufacturing of customizable thermal insulation materials in a sustainable, cost-effective, and eco-friendly manner.