High-Internal-Phase Pickering Emulsions for Enhanced Sound-Absorbing Materials

This work introduces a simple, efficient, and reliable approach for producing acoustic porous materials by using solid-stabilized emulsion templates. The technique allows for precise control of the pore size through straightforward emulsification processing conditions, highlighting its potential for developing multifunctional acoustic foams. The microstructure of the porous material was investigated using X-ray microtomography and open pore network modeling. The correlation between processing conditions, porous microstructure, and acoustic performance was determined. The findings reveal that the desired sound absorption performance can be achieved by adjusting the rotational speed during emulsification, which affects droplet size and ultimately results in targeted pore size, connectivity, and tortuosity. Notably, a near perfect sound absorption coefficient at 1100 Hz was achieved for samples with largest pores, highest porosity, and greatest connectivity. Furthermore, samples with medium porosity and pore size, but the highest tortuosity, exhibited maximum sound absorption below 500 Hz, despite a thickness of only 3 cm. This performance is particularly notable, as it is challenging to achieve with conventional acoustic foams, demonstrating the potential of this novel approach for developing high-performance acoustic materials over broad ranges of frequencies.