Biobased aerogels that combine intrinsic sustainability with superior sound absorption performance are emerging as efficient, eco-friendly solutions for next-generation noise control. Here, we report a urea-assisted strategy that is both cross-linker-free and readily scalable for fabricating stable monolithic chitin aerogels with tailorable pore structure. Raising the urea pretreatment solution (UPS) concentration from 2 to 6 wt % progressively decreased the average pore diameter of the chitin aerogels from 86.88 to 15.78 μm, reduced the porosity from 96.07 to 94.11%, and increased the bulk density from 0.06 to 0.09 g cm–3. A low-urea formulation (2 wt % UPS) generated a highly porous, large-pore network that endowed the aerogel with efficient broadband sound absorption and favorable thermal insulation: the effective bandwidth with absorption coefficient α > 0.9 spanned 3400 Hz (accounting for 58.6% of the measured frequency range), the peak absorption coefficient (αp) reached 0.97 at 4100 Hz, and the thermal conductivity was 0.044 W m–1 K–1. Conversely, a high-urea formulation (6 wt % UPS) produced a dense, small-pore structure that enhanced compressive resistance, ignition resistance, and visible diffuse reflection performance: the Young’s modulus increased to 260 kPa, the limiting oxygen index (LOI) reached 42.1%, and the average diffuse reflectance in the visible region was 92.16%. This study presents a straightforward strategy to tailor the macroscopic properties of chitin aerogels by engineering their pore structure, holding significant potential for advancing biobased acoustic materials across various applications.
Wan et al. (Fri,) studied this question.
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