Dual-scale pore structured composite fibrous sponges with enhanced waterproof properties for high-efficiency broadband noise absorption

Electrospun ultrafine fibrous materials demonstrate significant potential for noise reduction applications. However, electrospun fibers are predominantly deposited as two-dimensional fibrous membranes, which exhibit limited broadband noise absorption capabilities. Although recently developed three-dimensional (3D) electrospun fluffy ultrafine fibrous sponges have shown enhanced noise absorption performance, their waterproof properties remain insufficient. Here, we propose a method to prepare dual-scale pore structured composite fibrous sponges with waterproof functionality via a continuous two-step electrospinning combined with humidity-induced phase separation and thermal cross-linking. The synthesized composite fibrous sponges are lightweight (density of 11 mg cm⁻³) and imparts exceptional compression performance, maintaining structural integrity after 1000 compression cycles at 60 % strain. The fibrous sponges also exhibit excellent hydrophobicity (water contact angle of 143°) and water pressure resistance (93.2 kPa). More importantly, the dual-scale pore structure endows the sponges with superior broadband noise absorption performances, with noise reduction coefficients reaching 0.57. This work provides new insights into the development of multifunctional broadband noise-absorbing materials.