Synthesis of a zeolite@mesoporous silica composite to improve the low-frequency acoustic performance of a miniature loudspeaker system.

Herein, a zeolite@mesoporous silica composite (Z@MS) with a hierarchical porous structure was synthesized and employed as the filling material in miniature loudspeakers. The material was synthesized via a simple surfactant-directed sol-gel process in which MFI zeolites with a high silica-alumina ratio (>1000) were encapsulated in mesoporous silica with worm-like pores templated by Brij 72 under acidic conditions. Pressure spray drying technology was adopted to reassemble the intermediate slurry into hierarchical porous microspheres with large particle sizes (∼200 µm). The resonance frequency of the miniature loudspeaker system decreased by 339.77 Hz upon loading Z@MS as the filling material. The excellent acoustic performance can be considered as the result of a synergy of respective energy transmission effects among hierarchical porous structures.