In the field of high-performance thermal insulation materials, aerogels are widely used in buildings, industrial equipment, and piping systems due to their extremely low thermal conductivity and excellent thin-layer insulation capabilities. Besides insulation performance, the stability of materials in humid environments is also a key engineering concern. Whether an aerogel possesses good moisture resistance directly affects its long-term performance and system safety. This article explains the moisture resistance of aerogels from the perspectives of material structure and engineering applications.

First, from the perspective of the material's microstructure, aerogels are characterized by a nanoscale porous structure, with air as the primary component in the pores, which is the key basis for achieving their low thermal conductivity. Traditional aerogels, without hydrophobic treatment, easily absorb moisture on their surface, causing water to occupy the pores and thus increasing the thermal conductivity. Therefore, modern engineering aerogel products typically undergo surface modification processes to give them stable hydrophobic properties, which is an important prerequisite for moisture resistance.

Second, hydrophobic treatment plays a decisive role in moisture resistance. Hydrophobically modified aerogels exhibit hydrophobic surface properties, making it difficult for moisture to penetrate the internal pores. Even in high-humidity environments, they maintain relatively stable structures and thermal properties. These aerogels significantly outperform untreated products in terms of water absorption and moisture permeability, making them more suitable for complex environments and long-term operating conditions.

Third, from an engineering application perspective, the moisture resistance of aerogels is not solely determined by the material itself but is closely related to system design. In practical applications, aerogels are often used in the form of felts, boards, or composite materials, typically requiring the use of a moisture barrier or outer protective system. If the system's sealing design is inadequate, moisture can still penetrate through gaps during long-term operation, affecting overall performance. Therefore, a reasonable system structural design is crucial for ensuring the moisture resistance of aerogels.

Fourth, the focus of moisture resistance varies under different environmental conditions. In building envelopes, aerogels need to withstand seasonal humidity changes and condensation risks; their moisture resistance helps maintain stable insulation performance. In industrial equipment or pipeline insulation, aerogels are often exposed to high humidity or alternating hot and cold environments; good hydrophobic properties help reduce condensation and corrosion risks, improving system safety.

Fifth, moisture resistance also relates to the long-term durability of the material. Repeated exposure to moisture and drying during use can cause structural performance degradation, affecting mechanical strength and insulation effectiveness. Aerogel products with stable moisture resistance exhibit less performance change over long-term operation, reducing maintenance frequency and total life-cycle costs.

Overall, the moisture resistance of aerogels stems from the synergistic effect of the material's inherent hydrophobic structure and system-level moisture-proofing measures. In selecting building insulation materials, the hydrophobic performance indicators, application methods, and system design of aerogel products should be carefully considered. Scientific selection and standardized application are crucial to fully leveraging the insulation advantages of aerogels in humid environments and ensuring long-term stable system operation. This is one of the important reasons why aerogel materials have been gradually promoted in engineering practice.