Ultra-thin FeBTC/PI/Porous Ceramic Composites with a structural coupling strategy for noise absorption

The effective utilization of sound-absorbing materials is the primary approach to treat noise pollution, which represents a principal public health and environmental issue. However, current research on acoustic absorption materials has several drawbacks, including narrow sound absorption frequency bands, low sound absorption coefficients, and excessive material thickness. Herein, we propose a facile sound-enhanced strategy that integrates a micro-sized polyimide (PI) membrane network and nanoscale FeBTC metal-organic frameworks into a submillimeter porous ceramic with high open porosity and multiscale pore structure. The enhancement of broadband sound absorption performance can be achieved by adjusting the freeze-casting temperature and precursor solution concentration to regulate the distribution density of the PI membrane network. Furthermore, the med-low frequency acoustic performance was further enhanced by in-situ growth of FeBTC within the fabricated organic-inorganic composites featuring a dual network structure. Across a broadband frequency range of 500 Hz to 6300 Hz, the composites exhibited an average sound absorption coefficient (SAC) of 0.64 and an average sound transmission loss (STL) of 20.5 dB at a thickness of 15 mm, which was significantly higher than that of commonly available noise reduction products and advanced sound absorbers ever achieved. The synergistic sound absorption effects of the hierarchical structure play a significant role in achieving a remarkable noise reduction ability. Moreover, the low thermal conductivity and excellent environmental stability of this composite material make it suitable for a wide range of applications requiring broadband noise control, including building design, transportation, and precision instruments.