This paper describes the synthesis and the characterisation of the phase behaviour of series of siloxane and sissesquioxane based liquid crystals. With increasing the size of the organo-silicone core an increase of the glass and phase transition temperatures occurs. A systematic variation of the branching of the cores and the side-chains yields information about the structure-property relationship of these materials, e.g. cores with defined topology are found to exhibit lower glass transition temperatures than comparable cyclic systems.