Preparation of low-thermal-conductivity and high-strength GPTMS polymer cross-linked SiO₂ aerogels via a two-step modification method

Although recent studies on polymer cross-linking modification have improved the mechanical properties of SiO₂ aerogels, they often overlook thermal insulation performance, limiting broader applications. To achieve synergistic optimization of thermal and mechanical properties, this work employed tetraethyl orthosilicate (TEOS) as the silica source, (3-glycidyloxypropyl)trimethoxysilane (GPTMS) as the organic precursor, and diethylenetriamine (DETA) as the crosslinking agent; a two-step modification method combining precursor modification and hydrothermal aging was adopted, upon which DETA was further introduced into the aging solution to regulate the microstructure of the aerogels, and GPTMS polymer-crosslinked SiO₂ aerogels (GDSA) were ultimately obtained via ambient pressure drying. The study systematically explores the effects of the modification method and conditions on material structure and properties. Notably, the GDSA-50 sample, obtained via precursor modification and hydrothermal aging with 0.05 mol/L DETA, exhibits an low thermal conductivity of 0.0228 W·m⁻¹K⁻¹ and a high compressive strength of 1.829 MPa at 20 % strain. This work offers a novel route to developing polymer cross-linked aerogels with optimized thermal and mechanical properties, expanding their application prospects in high-performance thermal insulation.