High Compression Strength and Thermal Insulation Silica Aerogel Monolith with Scaffold of a Cyclic Olefin Siloxane Co-Oligomer via Ambient Pressure Drying

Abstract

Silica aerogels have attracted great interest for their unique nanopore structure and high porosity. Silica aerogel monoliths made by supercritical fluid drying or freeze-drying exhibit brittleness and low strength, which limit their practical applications. It is still a challenge to produce silica aerogel monoliths via ambient pressure drying. Herein, silica aerogels reinforced by cyclic olefin siloxane co-oligomers with extremely high mechanical strength using ambient pressure drying at elevated temperatures are demonstrated. Benefiting from the one-pot synthesis of siloxane with a norbornene structure and following copolymerization, hydrophobic silica aerogel monoliths can be prepared without additional modification, which is promising for industrial production. The resulting ambient pressure dryingcyclic olefin siloxane co-oligomer (APD-COSC) aerogels show excellent compression strength (35.7 to 199.3 MPa) and high modulus (19.6 to 108.3 MPa). The APD-COSC aerogel with a 5/95 ratio of cyclic olefin siloxane to vinyl siloxane exhibits a pronounced cyclic compression resistance of 3.48 MPa for 200 cycles with only 5.1% irreversible strain. Specifically, it exhibits a low thermal conductivity (39.8 mW m −1 K −1 ) and outstanding puncture resistance, making it a promising material for the thermal insulation layer in battery modules. The combination of thermal insulation performance and excellent mechanical strength may enable the aerogel to be an attractive material in the field of thermal insulation for spacecraft, industrial pipelines, and building layers.