Ultrahigh-strength silicone aerogels reinforced by an armor-like epoxy framework via a temperature-controlled sequential reaction strategy.

ABSTRACT

Aerogels with low density and high porosity are extremely attractive for high-performance insulation, but their brittleness, complicated fabrication, and poor mechanical properties greatly limit their practical applications. Herein, we report an ultrahigh-strength silicone aerogel with an armor-like epoxy framework via a temperature-controlled sequential reaction strategy. The key to this synthesis is forming a Si-O-Si framework via the polycondensation of silanes at 100 °C, followed by in-situ armoring an epoxy framework via an intermolecular cyclization at an elevated temperature of 150 °C. Owing to the enhanced framework, the resulting aerogel could withstand capillary tension in the drying process, enabling it to be dried at ambient pressure without shrinkage. The obtained aerogel possesses a tunable density of 0.17-0.45 g/cm3 and ultrahigh-strength with compressive modulus up to 37.8-244.3 MPa, which surpasses other polymer-reinforced silicone aerogels by a factor of five in mechanical properties. It also demonstrates outstanding thermal insulation, with an extremely low thermal conductivity from 0.025 to 0.051 W m-1 K-1 at room temperature, and maintains thermal characteristics across a temperature range of -20 to 300 °C. Furthermore, the aerogel composites prepared by the reinforcement of low-density fiber mats have tunable densities of 0.36-0.87 g/cm3, much enhanced tensile strengths of 15.9-72.3 MPa, and low thermal conductivities at room temperature of 0.042-0.078 W m-1 K-1. This study presents a cost-effective method for enhancing the production of silicone aerogel materials, offering considerable opportunities for their application in insulation, energy transport, and the aerospace sector.