Highly Ordered Organic Piezoresponsive Materials Obtained by Cross-linking Electroresponsive Columnar Liquid Crystal Compounds

An N,N′-diphenylurea derivative possessing six oleyloxy groups exhibited hexagonal columnar liquid crystal phases, and the columnar molecular aggregates were cross-linked with applying an electric field to produce a highly-ordered thin film which has a polarity in the thickness direction. The resulting aromatic polyurea film showed a relatively large vertical piezoelectric constant (d33 of 6.1 pm/V). An N,N′-diphenylurea derivative possessing six oleyloxy groups exhibited hexagonal columnar liquid crystal phases, and the columnar molecular aggregates were cross-linked with applying an electric field to produce a highly-ordered thin film which has a polarity in the thickness direction. The resulting aromatic polyurea film showed a relatively large vertical piezoelectric constant (d33 of 6.1 pm/V).