Enhanced Broadband Acoustic Absorption in Commercial Foam via Multiwall Carbon Nanotube-Induced Pore Reconstruction

Noise pollution is an urgent environmental issue that leads to a series of adverse effects on human physical and mental health. Porous materials with rationally designed micropores or channels can effectively absorb noise across wide frequency ranges, making them a well-established candidate for mitigating acoustic propagation. However, common porous materials with a singular pore structure face a trade-off between acoustic absorption efficiency and thickness. Herein, this challenge is significantly mitigated by reconstructing the pore structure of commercial melamine foam using multiwall carbon nanotubes (MWCNTs). The melamine/MWCNTs foam exhibits multiscale composite pores, high porosity, and increased specific surface area while preserving the shape and thickness of the initial melamine foam. Due to increased energy dissipation from the porous structure and the resonance effect of MWCNTs, the 10 mm thick composite porous absorber exhibits an average absorption coefficient of ≈70% from 1300 to 6000 Hz, representing a 196.5% increase compared with that of initial melamine foam. The reconstructing pore structure by loading MWCNTs is a simple and general method for improving the acoustic absorption coefficient. It can be extended to other complex morphologies or material systems, offering significant application potential in noise control, acoustic instruments, and architectural design.