The thermal stability of silicones stems from the thermal stability of Si-O and Si-CH3 bonds which are themselves thermally stable. However, the partially ionic nature of these bonds (51%), means that they can be easily destroyed by concentrated acids and alkalis at ambient temperatures.
Many industrial fluids are formulated with silicones as a base since they have good high temperature resistance and their physical characteristics vary very little, even under extremely variable temperature conditions. Fluids that convey heat are used to heat or cool chemical reactors and to produce constant temperature baths used to test measuring devices that must function at high temperatures. They are also used to cool and insulate medium-power transformers that supply our towns and industries with electricity.