Multifunctional elastic aerogels of nanofibrous metal−organic framework for thermal insulation and broadband low-frequency sound absorption

Generally, porous materials are good candidates for sound absorption and thermal insulation. However, low sound absorption coefficient under 1000 Hz, low mechanical stability and poor consistency of performance hinders the wide applications of porous materials. In this study, we develop a kind of aerogel (PAN@ZIF-8-Kevlar aerogel) with well-designed hierarchical and tortuous porous structures to consume the low-frequency sound, hinder thermal transmission. The sound absorption coefficient of the PAN@ZIF-8-Kevlar is as high as 0.99 at 500Hz; average sound absorption coefficient of the material at 250, 500, 750, and 1000 Hz reaches 0.73. In addition, the thermal conductivity of PAN@ZIF-8-Kevlar is similar to that of air, thermal conductivity is near that 24.61 mW m−1 K−1. Notably, the PAN@ZIF-8-Kevlar aerogels also exhibit durable and stable cycling performance. The material retains its structural stability and retains its original low frequency sound absorption properties after 500 compression cycles. The hydrophobic material provides them with good moisture resistance (the water contacts angle (WCA) of PAN@ZIF-8-Kevlar-90 wt% aerogel was 143.3°). These favorable properties indicate that the composite nanofibers aerogel has potential options for sound absorption, thermal insulation in vehicles, buildings, and indoor reverberation.