Direct visualization of the formation of single-molecule conjugated copolymers.

Electrochemical polymerization of two different kinds of thiophene monomers on an iodine-covered gold surface created highly assembled conjugated copolymers with different electronic structures. A scanning tunneling microscope revealed images of several linkage types: diblock, triblock, and multiblock. The single strand of conjugated copolymers exhibited an anomalous swinging motion on the surface. This technique presents the possibility of understanding the copolymerization process from the different monomers on the single-molecular scale and of building single-molecule superlattices on a surface through controlled electropolymerization.