Lightweight, strong and thermally insulating polymethylsilsesquioxane- polybenzoxazine aerogels by ambient pressure drying

Lightweight and high-strength aerogels are specially required in thermal insulation and thermal protection. However, maintaining light weight and high-strength still represents a formidable challenge. Herein we explore a strategy to introduce polyvinylmethyldimethoxysilane (PVMDMS) into polybenzoxazine (PBO) for enhancing the skeleton, and PVMDMS-PBO aerogels were prepared by sol-gel method and ambient pressure drying. The resulting PVMDMS-PBO aerogels possess a 3D nano-porous network structure, and the density can be as low as 0.11 g/cm 3 . The compressive strength of PVMDMS-PBO aerogels at 10 % strain (10% ε) is 0.55 MPa, much higher than the 0.12 MPa at 10% ε of the pure PBO aerogels with a similar density of 0.13 g/cm 3 . With increasing PVMDMS content, the thermal conductivity of PBO aerogel decreased from 0.0489 W/(m·K) to 0.0432 W/(m·K). The peak heat release rate decreased from 125.0 W/g to 91.7 W/g. The lightweight, high strength, excellent flame retardancy and thermal insulation of PVMDMS-PBO aerogels make them conducive to thermal insulation application. Highlights The PVMDMS-PBO aerogels possess a low density of 0.11g/cm3 by ambient pressure drying. The PVMDMS-PBO aerogels exhibit high compressive strength of 0.55 MPa at 10 % stain. The PVMDMS-PBO aerogels have superior thermal insulation and flame retardancy.