Mesophase Behaviour of Some Semiflexible Trimeric Compounds

Abstract

The synthesis and the phase behaviour of a class of semiflexible mesogenic compounds, containing two terminal α-methylstilbene and one central p-biphenyl groups, linked each other by flexible spacers, is reported. Their phase behaviour has been investigated by DSC, X-ray diffraction and optical methods. All compounds show liquid crystalline polymorphism; in particular all but one exhibit a highly ordered smectic phase whose nature is discussed. The occurrence of enthalpic and entropic changes at the nematic-isotropic phase transition, which are sensibly higher than those reported for monomeric and dimeric model compounds of semiflexible polymers, is also discussed.

• mesogenic
• smectogenic
• mesomorphic
• oligomers
• polymers