Highly Efficient Thermo-Acoustic Insulating Aerogels Enabled by Resonant Cavity Engineering.

Area of Science:

• Materials Science
• Acoustics
• Nanotechnology

Background:

• Lightweight, flexible, and noncombustible thermo-acoustic insulating (TAI) materials are crucial for weight-sensitive applications like vehicles and aerospace.
• Current TAI materials often lack diverse resonant cavities, limiting their broadband and efficient acoustic absorption capabilities.

Purpose of the Study:

• To develop a novel method for fabricating high-performance TAI aerogels with enhanced acoustic responsiveness.
• To create materials with a wide range of resonant cavity sizes for broadband sound absorption.

Main Methods:

• A layer-by-layer freeze-casting technique was employed using varied nanofibers and ice particulates.
• This method resulted in vertical pore channels and random holes, creating a cellular network structure.
• The nanofiber membranes were functionalized as ultrathin nanofiber drums to enhance acoustic properties.

Main Results:

• The fabricated aerogels exhibited widely distributed resonant cavities ranging from 0.5 to 300 μm.
• A high noise reduction coefficient of 0.65 was achieved across a broad frequency range (63-6300 Hz).
• The material demonstrated excellent thermal insulation with a low thermal conductivity of 0.026 W m⁻¹ K⁻¹.

Conclusions:

• The layer-by-layer freeze-casting method enables the bottom-up fabrication of superelastic cellular aerogels.
• These high-performance TAI aerogels offer significant potential for energy-saving devices, buildings, and broadband acoustic absorption.
• The unique cellular structure with nanofiber drums provides efficient sound wave dissipation and thermal insulation.