Towards in-plane metathesis polymerization at self-assembled monolayers of norbornene adsorbates on gold surfaces

Ring-opening metathesis polymerization (ROMP) of norbornene thiol derivative 1 and bis(thioether) 2 was carried out both on monolayer-protected gold nanoclusters (MPCs) and at self-assembled monolayers (SAMs) on a gold(111) surface. Metathesis polymerization was carried out by using the Grubbs catalyst. Mixed monolayer-protected MPCs of 1 were prepared using 1 and dodecanethiol as the ligands. ROMP on the MPCs showed both inter-and intra-particle polymerization. In-plane polymerization of SAMs of 1 and 2 on flat gold was carried out. Electrochemical impedance spectroscopy (EIS) indicated that the SAMs had retained their thickness and order after polymerization. Furthermore, EIS showed that the polymerized layers were more resistant to solvent-assisted desorption. Electrochemical reductive desorption studies showed a more negative peak potential for SAMs of 1 upon polymerization, which is attributed to the formation of multiple attachment points, decreased solubility and possibly increased resistance against permeation of the electrolyte.