How do silicone rubbers remain soft at very low temperatures?

Silicone rubbers remain soft at very low temperatures primarily due to the unique molecular structure of their backbone, which consists of alternating silicon and oxygen atoms.21

The Si–O bonds allow the molecules to rotate freely, which grants the polymer chain a high degree of flexibility even at extreme cold. Because of this internal flexibility, silicone rubber possesses the lowest glass transition temperature of any elastomer—reaching as low as −125 °C (−195 °F). Since the glass transition temperature is the point below which molecules become locked in a rigid, glassy state, silicone's exceptionally low threshold ensures it retains its resiliency and soft, flexible properties in environments where other materials would become brittle.213