Facile, efficient routes to diverse protected thiols and to their deprotection and addition to create functional polymers by thiol-ene coupling

Carbazole, dinitrobenzoate, phenol, pyridine, and 4-cyano-4 '-alkoxybiphenyl side groups were grafted onto pendant vinyl groups of polybutadiene (PB) by thiol-ene addition to yield functional polymer of polydispersity equal to that of the precursor material. Synthesis protocols that are clean (> 90% conversion to desired product) and scalable were developed to incorporate a protected thiol group into functional precursors. The resulting acetyl or benzoyl thioesters are suitable for long-term storage, and are conveniently deprotected and added to polymer in a matter of hours in a straightforward procedure that does not require isolation of the thiol intermediate. Alternatively, PB functionalization could be achieved with equal success by reaction with P-mercaptoethanol (BME), and subsequent esterification of the incorporated hydroxyl groups with a suitable acyl halide. The chemistry described can potentially be applied to add any side group onto any polymer, copolymer, or block copolymer displaying pendant vinyl groups.