Surface-initiated living radical polymerization with organotellurium compounds

Organotellurium-mediated living radical polymerization (TERP) was for the first time adopted to surface-initiated graft polymerization. An alkyl iodide-based initiator was immobilized on silicon surface, and the graft polymerization of methyl methacrylate was carried out in the presence of dimethyl ditelluride (catalyst) and an unimobilized alkyl iodide (free initiator) to control the polymerization. The number-average molecular weight M_n for the free polymer (produced from the free initiator) linearly increased with conversion, and the polydispersity index was about 1.3, suggesting good control in the molecular weight and the polydispersity for the graft polymer. The thickness of the graft layer was approximately proportional to the M_n of the free polymer, suggesting a constant graft density during the polymerization. The graft density was about 0.6 chains/nm ², which is similar to the highest ever achieved density (0.8 chains/nm² achieved by other living radical polymerizations), being in the so-called concentrated polymer brush regime. Thus, a well-defined concentrated polymer brush was successfully synthesized by adopting TERP to the graft polymerization.