To improve this polymerization procedure, we first changed the initiator layer. While use of norbornene-based SAM pre-initiator layers has become common for SI-ROMP since a seminal Whitesides paper, we were concerned that this technique might give unpredictable results based on the deposition of the norbornene trichlorosilane layer. Small amounts of water can dramatically affect the nature of the deposited trichlorosilane layer for all trichlorosilane-Scheme 2: An improved scheme for preparing pCOT films using a vinyl initiator layer and GG2 catalyst. based thin films, giving highly variable results from batch to batch. Silanes lacking a long, straight chain to drive self-assembly are also poorer at forming a reproducible monolayer, increasing the variability of the initiator films. As an alternative, vinyl-terminated films have been shown to be effective initiator layers for SI-ROMP. We therefore moved to a simpler vinyl-based initiator monolayer based on p-styrenethiol, which can immobilize the catalyst by simple cross-metathesis. Rather than Grubbs' generation 1 catalyst, we used the more reactive generation 2 catalyst, hoping that the higher rate of initiation would help compensate for the lower ring strain of COT. (Scheme 2) Attempts to use the much more reactive 3bromopyridine-ligated version of the Grubbs catalyst, now officially known as GG3, actually gave films no thicker on average than GG1. We speculated that this surprising result was due to the catalyst being reactive enough to rapidly backbite the growing chain, cleaving it from the surface. AFM imaging of surfaces at various time points (Figure ) revealed a time regime during which growth was still active. Quenching of the surface-initiated polymerization at the 1 h time point with vinylferrocene gave a strong surface-bound ferrocene signal in cyclic voltammetry, corresponding to roughly 20% of the maximum theoretical coverage possible for a smooth close-packed monolayer on gold. (Figure ) Varying the scan rate in the cyclic voltammetry of the pCOT film allows analysis of the kinetics of electron transfer between the electrode and the endgroup via Laviron's formalism and the plot of (E a,c -E f ) vs. ln(scan rate), Figure . The critical scan rates a and c of the system are determined by extrapolation of the linear portion of the curve to (E a,c -E f ) = 0, and the electron-transfer coefficient is assumed to be 0.5. The average rate constant for electron transfer were cal-culated from the electron-transfer coefficient and the critical scan rates. The inset shows peak currents as a function of scan rate, which display the linearity expected of a species permanently bound to an electrode. The estimated rate constant of 2-3 s -1 (Figure ) is comparable to the values obtained by other workers 23 using the same electrochemical technique for single monolayers of oligo(phenylenevinylene) and oligo(phenyleneethynylene), an impressive result considering that the average thickness of the pCOT film is six to eight times that of the reported monolayers. This result suggests that charge transfer through the pCOT film is rapid, with the limiting factor possibly being transfer through the gold-thiol linkage and aryl ring to the pCOT film. This interpretation also implies that the electron-transfer characteristics of this system might be improved by changing the nature of the linker molecule used to immobilize the ruthenium metathesis catalyst; it has been suggested that the thiol-gold linkage presents a significant barrier to electron transfer, with thiocyanate-gold, among others, having a lower barrier. of the redox couple can be obtained, as well as the surface coverage of the electroactive ferrocene species. The surface coverage of 1x10 -10 mol/cm 2 is only around 20% of that of a closely packed monolayer. Figure : Cyclic voltammetry of ferrocene-terminated, iodine-doped pCOT films at (top to bottom) 15m, 30m, and 60m polymerization times. The irreversible oxidation peak may be due to ruthenium catalyst not fully removed from the film.