Three-dimensionally ordered polymer networks with a helicoidal structure

Abstract

It is demonstrated that densely cross-linked polymer networks with a helicoidal order in the nematogenic bridging units can be created by photoinitiated polymerization of liquid-crystalline diacrylates containing a chiral dopant. The natural pitch of the monomeric mixture is controlled by the dopant concentration, while the total rotation angle of the molecular helix and thus the actual pitch of the material between two unidirectionally rubbed substrates are supplementarily adjusted by the angle between the director at both interfaces and by the film thickness. During polymerization of a monomeric film the rotation angle remains constant, while the pitch may decrease due to polymerization shrinkage.