Low Thermal Conductivity Silicone Aerogels Tuned by Composite Surfactants

The excellent flexibility of silicone aerogels has attracted attention. However, the thermal conductivity of silicone aerogels is higher than that of inorganic silicone aerogels. Thermal conductivity can be reduced by increasing the thermal insulation of silicone aerogels while maintaining their flexibility. Herein, we successfully propose an ultrasimple strategy to prepare thermally conductive silicone aerogels using composite surfactants. Cetyltrimethylammonium chloride and cetyltrimethylammonium bromide were selected as complex surfactants with effective emulsification ability. The synthesized cationic/cationic surfactant emulsion aerogels exhibited high porosity (93%), flexibility, remarkable adiabatic properties (0.021 W m^-1 K^-1 thermal conductivity at 25 °C), thermal stability (68.71% thermogravimetric residue at 0-800 °C), and excellent flame-retardant capacity (vertical combustion test grade = V-0; limiting oxygen index = 27.30%), which made cationic/cationic surfactant emulsion aerogels a candidate material in the field of thermal insulation.