Endgroup and Sidechain Functionalization of Surface-Initiated ROMP Thin Films: Progress Towards ROMP-Based Molecular Wires

Abstract

We report functionalized thin films based on endgroup and sidechain modification of polymer films prepared using surface-initiated ring-opening metathesis polymerization (SI-ROMP). Poly(norbornene) can be readily end-functionalized by cross-metathesis with various vinyl chain-transfer agents; however, polyacetylene prepared from cyclooctatetraene (pCOT) is inefficiently end-functionalized (ca. 20% of monolayer surface coverage), while a fused norbornene-teraryl monomer was not successfully endfunctionalized. While these techniques can be used to tune the wettability of a surface or to coat a surface with a thin film of conjugated polymer, efficient "molecular wire" architectures, where a conjugated, intrinsically conducting polymer connects a surface and a molecular species, have still not been constructed using ROMP. We propose a systematic strategy for doing so using the active ester-bearing monomer NbNHS, and demonstrate this strategy's feasibility by preparing SI-ROMP films of poly-NbNHS up to 45 nm in thickness and demonstrating these films' reactivity with a primary amine.