Liquid Crystalline Ordering in the Self-Assembled Monolayers of Tethered Rodlike Polymers

We show that tethering rodlike polymers onto solid surfaces by their chain ends with a moderate grafting density can lead to highly oriented anisotropic self-assembled monolayers (SAM) with thickness identical to the diameter of single chain through liquid crystalline ordering. The polymers employed for this study were di- or triblock copolymers composed of poly(n-hexylisocyanate)(PHIC), a rodlike polymer, and poly(2-vinylpyridine)(P2VP), a surface-reactive coil. The block copolymers formed SAM of PHICs tethered to the surface through adsorption of P2VP onto mica. Planar nematic ordering occurred to the PHIC chains when the monolayer was exposed to the vapor of selective solvents. Anisotropic SAMs with long-range order were obtained by exposing the monolayer to THF vapor, which was accounted for by reorganization of PHIC chains with change of anchoring points through partial sorption/desorption of P2VP segments by THF vapor.