Mobility of mesogenic side-chains in liquid crystalline polymers based on the Baylis-Hillman reaction

The hydrodynamic and electro-optical (Kerr effect) properties of two side-chain liquid crystalline (SCLC) polymers have been investigated in benzene and chloroform solution. The polymers are unique in structure and have been prepared using the Baylis-Hillman methodology. The polymers contain (a) a polar group (CN or COCH3) along the polymer backbone and (b) a hydroxyl group on the spacer group which is adjacent to the point of attachment of the spacer/mesogenic side groups to the polymer backbone. Molecular dimensions and the Kerr constants were determined for two SCLC polymers and for three low molar mass materials, the n-alkoxycyanobiphenyls (nOCB), which are structurally similar to the side chain used in the SCLC polymers. These results are discussed in relation to the chemical structure and dipole moment of the monomer unit. Dielectric and electro-optical properties of the SCLC polymer containing the —CN group along the polymer backbone were found to be similar to the properties of the nOCB compounds. The difference in the mesogenic side-chain mobility of the polymers was related to the dipole-dipole interactions of the polar groups along the polymer backbone.