Surface-Grafted Polymers from Electropolymerized Polythiophene RAFT Agent

The synthesis of grafted homopolymer and block copolymer films is reported using a surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization from electropolymerized polythiophene on indium tin oxide (ITO) and Au electrode surfaces. The polythiophene macro-RAFT agent was electrodeposited by cyclic voltammetry (CV) from thiobenzoate-functionalized terthiophene monomers. The ultrathin films on Au surfaces were investigated using atomic force microscopy (AFM), static contact angle, X-ray photoelectron spectroscopy (XPS), and ellipsometry. On the other hand, the RAFT agent-modified ITO substrate was monitored by UV-vis to track the electropolymerization of the RAFT agent and formation of pi-conjugated polymer. Molecular weight (MW) and polydispersity index (PDI) were determined from sacrificial polymerization in solution. AFM imaging revealed typical polymer layer morphology for the films. Investigation of film thicknesses by ellipsometry and A FM profilometry gave comparable results. XPS showed atomic percentages close to expected values, accounting for variations based on component thickness and XPS sensitivity. Diblock copolymer brush formation revealed capabilities of a conventional SI-RAFT procedure using a polythiophene macroinitiator film.