Aerogels are a diverse class of ultralow density solids that combine multiple disparate and extreme materials properties into a single material envelope. Aerogel materials generally exhibit a high degree of porosity, high specific surface area, and superlative energy damping (thermal, acoustic, and impact) properties. The name aerogel may be misleading at first, as aerogels are dry, rigid or elastic foam-like materials—the name originates from the fact that aerogels are usually derived from wet gels, physically similar to edible gelatin, in which the liquid component of the gel has been replaced by a gas or vacuum in a way that preserves the gel’s sparse solid, porous backbone.

Silica aerogels are a common type of aerogel that combine ultralow thermal conductivity (as low as 10 mW m-1 K-1) with extremely low density (as low as 0.001 g cm-3), high specific surface area (500-2000 m2 g-1), low dielectric constant (as low as 1.02), and good optical transparency (~91% per cm), making them uniquely valuable as high-performance insulators, supports for chemical sensors and catalysts, and particle detectors. Some aerogels, such as aerogels made of carbon, metals, and carbon nanotubes, also exhibit good electrical conductivity, making them ideal substrates for electrodes in ultracapacitor/supercapacitor architectures, batteries, and desalination applications.

But read on—there’s much more to aerogels than just superinsulation and electrodes.

COMPOSITIONS

Aerogels are not restricted in composition to any particular substance, but rather are a high-definition porous geometry than can be taken on by a substance or combination of substances.

FORMS

Commercially speaking, aerogel materials are generally available in the following form factors:

Monoliths (i.e., shaped forms)

Particles (multi-millimeter to hundreds of microns mesh)

Powders (microns to hundreds of microns mesh)

Composite blankets (fiber meshes incorporating aerogel coatings or particles)

Thin films

Historically, native aerogel materials have been impractically brittle for industrial applications due to their extremely poor fracture toughness and relatively low compressive strength. Over the past decade, forms of aerogels that circumvent these limitations including composite aerogel/microfiber blankets and low-cost fine particles have been made commercially available and to date have had a measurable impact on energy efficiency in the oil and gas, daylighting, and performance coatings industries. Monolithic aerogels, however, potentially leverage the broader set of properties offered by the aerogel geometry better than these other forms and thus are emerging as a platform for enabling a wide array of novel technological applications.