Supramolecular cross-linking affords superelastic and fatigue-resistant cellulose-based nanocomposites with excellent thermomechanical properties and waterproofing performance

Abstract

Nanocellulose is one of the most abundant renewable resources on earth and is used in many applications due to its excellent physical and chemical properties, and it is an important biopolymer raw material to support human well-being. However, current cellulose-based aerogel nanocomposites are plagued by irreconcilable contradictions between thermomechanical and waterproofing characteristics due to their hygroscopicity. Herein, sustainable insulating cellulose aerogel nanocomposites are prepared from tempo-oxidized bamboo cellulose nanofibrils (CNFs) and polyvinyl alcohol (PVA) with a continuous orientation-free pore architecture formed by CNFs/PVA pre-hydrogel aggregates, which combine to become the basic structural unit for producing superelastic properties. The resulting lightweight CNFs/PVA aerogels (CNPA) with a hierarchical orientation-free pore architecture and density about 5–20 kg m3 achieve an optimal thermomechanical and insulation trade-off, demonstrating temperature-invariant compressibility (–100–500 ℃) and a low thermal conductivity of 38.2 mW m–1 K–1 at 300 ℃. Particularly, the flyweight CNPA retained its structural integrity after more than 106 cycles at ɛ=20 %, 105 cycles at ɛ=50 %, and 104 cycles at ɛ=80 %. Furthermore, CNPA also exhibits robust liquid-repellency with a WCA exceeding 160.3°. This lightweight cellulose-based nanocomposites, although constructed using an intrinsically hygroscopicity nanocellulose-constituent, is simultaneously superelastic, fatigue-resistant, thermomechanical, and waterproofing performance.