Alignment Properties of Hydrogen-Bonded Mesogens of Supramolecular Liquid-Crystalline Network Films Coated on an Alignment Layer

The films of a supramolecular liquid-crystalline (LC) network were spontaneously formed by intermolecular hydrogen bonds between multifunctional H-bond donor (HD) and H-bond acceptor (HA) molecules. A tricarboxylic acid, 2,5-bis{2-[2-(4-carboxyphenoxy)ethoxy]ethoxy}benzoic acid (1) was prepared for the use as a trifunctional H-bond donor. This donor was complexed with a bifunctional H-bond acceptor, trans-1,2-bis(4-pyridyl)ethylene (2). H-bonded complexes, 1/2, in the various ratio of donor to acceptor groups (HD/HA) were coated on a rubbed poly(vinyl alcohol) (PVA) film. These films exhibited homogeneous alignment when the ratio of HD to HA (HD/HA) was more than 1.025. These results suggest that the alignment properties of the mesogens in the complex films on the PVA film related to the value of HD/HA.