Thermotropic polyamides containing the benzophenone unit

The synthesis and structure-property relationship of fully aromatic homo- and copolyamides are described. They all contain the 3,4′-substituted benzophenone and diphenyl ether moiety in the main chain. The synthesis of the polyamides was performed at low temperatures with silylated aromatic diamines and aromatic acid chlorides. The polymers possess good solubility in dipolar aprotic solvents. They display thermotropic liquid crystalline properties. Based on results obtained by means of polarization microscopy, X-ray scattering, and molecular dynamics simulation a rather unusual structure is proposed. It consists of a superlattice composed alternatingly of smectic B layers and amorphous layers. The formation of smectic B layers is untypical for main-chain LC polymers without aliphatic spacers.