Surface-Grafted Rodlike Polymers: Adaptive Self-Assembled Mono layers and Rapid Photo-Patterning of Surfaces

Abstract

We present a new concept of functionalizing solid surfaces using polymeric self-assembled monolayers (PSAM) that are obtained by grafting onto solid surfaces an asymmetric block copolymer composed of a long rodlike block and a short surface-reactive block. Poly(n-hexylisocyanate)-b-poly[3-(trimethoxysilyl) propyl methacrylate] (PHIC-b-PTMSM) is synthesized via a living anionic polymerization and an atom transfer radical polymerization. The new rod coil block copolymer forms a polymeric self-assembled monolayer (PSAM) through covalent bonding of the sticky PTMSM block and planar adsorption of PHIC rodlike chains onto the substrate surface. The uniform PSAM with a thickness identical to the diameter of the rodlike chain is produced by the immersion coating method in a range of immersion solution concentrations and coating times. The PSAMs present unique properties thanks to the freedom of rotation of the end-grafted rodlike chains. The PSAMs exhibit nematic liquid crystalline ordering when the monolayer is fluidized by solvent vapor. A mixed SAM with a nanodot pattern is obtained by introducing a second coating agent of octadecyltrimethoxysilanes (ODTMS) onto the PSAM-coated substrate. The PSAM is micropatternable using photochemical cleavage of the anchoring blocks by brief exposure to UV. Use of the PSAMs as an additional dielectric layer in P3HT-based field effect transistors (FETs) is also demonstrated.