Norbornenyl-Substituted Thiophenes and Terthiophenes: Novel Doubly Polymerizable Monomers

The synthesis and polymerization of norbornenyl-substituted thiophenes ( 2 and 4 ) and terthiophenes ( 3 and 5 ) are reported. All monomers readily undergo ring-opening metathesis polymerization (ROMP) using the ruthenium catalyst, Cl 2 (PPCy 3 ) 2 Ru CHPh ( 1 ). The terthienyl monomers 3 and 5 were directly polymerized onto the surface of a gold electrode via electrochemical oxidation of the capping terthienyl units, while the direct electrochemical homopolymerization of 2 was not achievable, which is consistent with previous literature reports for similarly substituted thiophenes. Chemical polymerization of the terthienyl segments of 3 and 5 using FeCl 3 yielded insoluble materials. Finally, polymers obtained from the ROMP procedure were further cross-linked using the oxidative techniques described above, yielding highly networked materials which displayed an increase in thermal stability and electrical conductivity relative to their single-chain polymeric precursors.