Combined Electrodeposition and Electropolymerization Method to Produce Surface-Bound Polystyrenyl NHC Thin Films

Abstract

Polymeric N-heterocyclic carbene (NHC) films offer a promising strategy for generating durable protective coatings on metals. Polystyrenyl NHC films were constructed on gold in a one step process that combined electrodeposition and electropolymerization of styrenyl benzimidazolium halide precursors at -1.3 V vs Ag/AgCl for 5 min. Ellipsometry confirmed the nanometer scale films on Au were formed with thicknesses of 1.16 – 2.92 ± 0.15 nm, while non-polymerizable controls were ≤ 0.8 nm. Cyclic voltammetry showed strong surface passivation for all polystyrenyl NHC films relative to the monomeric analogues. Area selective deposition on the NHC precursors was evaluated on patterned Au/SiO2 with excellent selectivity factors up to 0.90. These results establish polystyrenyl NHC films as robust nanometer-thick inhibitor coatings that couple strong NHC–metal bonding with the hydrophobic insulating character of polystyrene.