Multifunctional ultralight nanocellulose aerogels as excellent broadband acoustic absorption materials

Noise pollution has become one of the environmental hazards in parallel with air pollution, water pollution, and solid waste pollution worldwide. Cellulose aerogel is a new porous sound-absorbing material that is highly efficient, green, recyclable, and degradable, showing bright prospect for the application in noise suppression. In this study, we fabricated multifunctional acoustic absorptive cellulose nanocrystal (CNC) aerogels by employing calcium chloride as the green crosslinker of CNC, followed by freeze drying. The as-prepared CNC aerogels exhibit excellent broadband acoustic absorption performance with a high maximum absorption coefficient of 0.99 (at 2960 Hz), an average absorption coefficient of 0.85 (in the range of 600–6400 Hz), and a wide absorption bandwidth of 4673 Hz with the absorption coefficient greater than 0.8. The dissipation mechanism of sound energy in the fabricated CNC aerogels is predicted by a designed porous media model. Moreover, good thermal stability, ultralight property (density of 0.036 g/cm 3 ), and high diffuse reflection characteristics (average diffuse reflectance of 98.17% for light) of these CNC aerogels were demonstrated as well. Such versatile aerogel materials not only pave the way for the development of sustainable and efficient acoustic absorption materials, but also have great potential applications in broad fields including construction, transportation, and environment acoustics.