Introduction

Scientists at Zhejiang University have designed a Polymeric Hybrid Silicone Aerogel reinforced with a silica mesh, that features low thermal conductivity, high mechanical strength, and is capable of acting as a thermal insulator even in the presence of flames. This is the key difference from conventional aerogels, which degrade when exposed to flames and therefore fail to function as insulators. The polymeric hybrid silicone aerogel can be used in electric vehicles, where long-lasting protection against flames is essential.

More specifically, they demonstrated that a 10-mm-thick panel is capable of keeping the temperature on the back side below 120°C for at least 25 minutes. The hybrid silicone aerogel also provides daytime cooling of approximately 7.7°C under midday solar radiation thanks to its reflectivity of approximately 95.5% of sunlight.

What Is an Aerogel?

definition

Aerogel is an extremely lightweight material (the least dense solid substance known, the lightest), composed of 99.8% air (gas) and 0.2% silica (solid)—the same material as glass. It has low density, excellent thermal insulation properties (capable of withstanding extremely high temperatures without deteriorating), and incredible mechanical strength. It is similar to a gel, except that instead of a liquid, an aerogel contains a gas. It is visually transparent, and to the touch it feels like foam rubber, although it is less soft.

A material that acts as a thermal insulator is capable of limiting the transfer of energy in the form of heat. This can be useful in construction, so that buildings exposed to sunlight can retain heat inside during the winter, thereby reducing energy consumption.

Types of Aerogel

• Ceramic-based aerogel: The most common type of aerogel, made of silica, is capable of absorbing infrared radiation. It can be used in construction for thermal insulation.

• Carbon-based aerogel: It consists of carbon particles on the order of nanometers (1 nm = 10⁻⁹ meters) that are covalently bonded. They can also be electrical conductors and are used in the creation of supercapacitors (devices capable of storing a significant amount of electrical energy). It is capable of absorbing infrared radiation and, as a result, can store solar energy.

• Metal-based aerogel: These are composed of alumina (aluminum oxide) and can be used as catalysts—that is, chemical species capable of accelerating a reaction.

• Polymer-based aerogel: They are composed of polymer chains (large molecules made up of numerous carbon and hydrogen atoms, all linked together) and are characterized by low cost, mechanical strength, and design versatility, which allows them to be used in a variety of applications. Their main drawback is structural collapse when exposed to flames because of the cracks that form during the manufacturing process.

According to the paper—ceramic, carbon, and metal aerogels are inherently nonflammable (unable to catch fire), but despite this, their use is limited due to their high cost, fragility, and complex manufacturing process.

Advantages of Polymeric Hybrid Silicone Aerogel

Scientists have created a Polymeric Hybrid Silicone Aerogel consisting of silicone polymer chains and what sets it apart from conventional aerogels is that its overall structure is reinforced by a silica network (the main component of glass). The final product is an aerogel with high porosity, low thermal conductivity (it conducts little heat, so it can be used as an insulating material), and mechanical resilience. According to the paper, a 10-mm thin silicone aerogel panel maintains a back-side temperature below 120°C for at least 25 minutes under a 1300°C flame, outperforming conventional aerogels.

Its greatest strength is its long-lasting protection when exposed to flames. When exposed to flames, tiny nanopores form on the walls of the pores, creating a sort of protective barrier.

The importance of the study

Polymeric Hybrid Silicone Aerogel offers a more advantageous alternative to conventional aerogels due to its high porosity, mechanical resilience, and low thermal conductivity. The most significant difference lies in its flame resistance; the resulting aerogel can be used in electric vehicles, where long-lasting flame protection is essential, and can also be used in buildings where there is a high demand for efficient thermal management.

Bibliographic sources:

1. Zhang, Z., Li, M., Li, D. et al. Mechanically resilient, hybrid silicone aerogel for thermal insulation, daytime radiative cooling and sustained flame protection. Nature Communications, 2026. DOI: https://doi.org/10.1038/s41467-026-78091-x

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