Highly Compressible\nMicro/Nanofibrous Sponges with\nThin-Walled Cavity Structures Enable Low-Frequency Noise Reduction

Increasing noise pollution has generated a tremendous\nthreat to\nhuman health and incurred great economic losses. However, most existing\nnoise-absorbing materials present a significant challenge in achieving\nlightweight, robust mechanical stability, and efficient low-frequency\n(<1000 Hz) noise reduction. Herein, we create highly compressible\nmicro/nanofibrous sponges with thin-walled cavity structures for efficient\nnoise reduction through electrospinning and dispersion casting. Manipulating\nthe phase separation driven by solution/water interaction in jets\nenables formation of fluffy fibrous frameworks, on which the deformation\nof casting dispersion is controlled to develop thin-walled cavity\nstructures consisting of semiopened cells and entangled networks.\nThe resultant sponges exhibit lightweight characteristics (2.2 mg\ncm<sup>–3</sup>) and mechanical robustness, integrated with\nremarkable low-frequency noise reduction capability (absorption coefficient\nup to 0.98) benefiting from vibration and viscous friction effects\nof cavity-structured skeletons. This work may offer new horizons for\ndesigning advanced fibrous acoustical materials, inspiring next-generation\nnoise-reducing devices in aerospace and transportation.