Combination of water-soluble chemical grafting and gradient freezing to fabricate elasticity-enhanced and anisotropic nanocellulose aerogels

Lignocellulosic nanofibrils (CNFs) are among the most well-known renewable and biocompatible materials. Aerogels assembled from these high aspect ratio CNFs are highly porous and ultralight. However, CNF aerogels ultimately exhibit unsatisfactory mechanical properties. This work reports the lamellar-aligned structural design to prepare an elasticity-enhanced CNF aerogel through the combination of chemical grafting with a water-soluble vinyl monomer and gradient freezing, thereby focusing on the relationship between structure and performance. Morphological characterization by scanning electron microscope showed that the large-scale lamellar/porous structure of the elasticity-enhanced aerogel exhibited flyweight densities of 3.31 mg/cm(3), porosity of 99.77%, enhanced elasticity at 70% strain, and over 85.4 times water adsorption (by weight) at 20 degrees C for 20 cycles. Moreover, the carbonized lamellar-aligned aerogel exhibited anisotropic electrical resistivity. The interesting effects of anisotropy and the more environmentally friendly preparation are important contributions to the CNF light porous materials. The fascinating large-scale lamellar-aligned renewable aerogel may be useful for applications such as energy storage, strain sensors, and thermal insulation.