The invention relates to 1,1-disubstituted cyclohexane derivatives containing one or more polymerisable groups, and to liquid-crystalline media comprising at least one compound of the formula I. At least one of the polymerisable groups is located at the geminally substituted position of the cyclohexane ring. The compounds are suitable for the stabilisation of liquid-crystalline phases. Examples of polymer-stabilised blue phases are indicated.