Simple and versatile synthetic route for the preparation of main-chain, liquid-crystalline elastomers

A new synthetic concept has been successfully used for the preparation of main-chain, liquid-crystalline elastomers (MC-LCEs). This approach consists of a one-step, platinum-catalyzed hydrosilylation between a low molar mass divinylic nematogen and a mixture of 1,1,3,3-tetramethyldisiloxane and 2,4,6,8-tetramethylcyclotetrasiloxane tin the appropriate equimolar amount), the disiloxane being used for the polymer chain extension and the tetrasiloxane as the cross-linker. Three new MC-LCEs, E1, E2, and E3, were prepared accordingly for which either the mesogenic unit or the cross-linking density was changed, further proving the versatility of the method. The mesomorphic properties include smectic C (Sc) and nematic (N) phases as characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD).