Precise size control of sub-10 nm structures of cholesteryl-containing mesogen-jacketed liquid crystalline polymers

Abstract

A series of mesogen-jacketed liquid crystalline polymers (MJLCPs) with polynorbornene as the main chain and cholesteryl mesogenic units at the ends of the side chain, PNbnChol (n = 1, 3, 5, which is the number of benzene rings in the rigid side-chain core), were prepared by ring-opening metathesis polymerization. The phase behaviors of the polymers were investigated by differential scanning calorimetry, polarized light microscopy, and one-dimensional/two-dimensional X-ray scattering. The polymer with one benzene as the rigid core in the side chain shows only a smectic phase with interdigitated packing of cholesteryl units at low temperatures and is amorphous at high temperatures. While polymers containing three or five benzenes in the rigid side-chain core provide two different SmA phases at different temperatures, a smectic phase with double-layer-like packing of cholesteryl units at low temperatures and the smectic phase with interdigitated packing of cholesteryl units at high temperatures. The introduction of cholesteryl to MJLCPs can fabricate precisely controlled sub-10 nm scale ordered structures that can be maintained at high temperatures.