SAMs functionalised by α-quaterthiophene as model for polythiophene grafting

A model of polythiophene grafting on a SAM functionalised by α-quaterthiophene is presented. The elaboration and characterisation of the dodecanethiol monolayer terminated by α-quaterthiophene are reported. Blocking level of substrates, structure of the alkyl chains and organisation of the quaterthiophene units as well as their chemical behaviour are analysed. HREELS spectra showed that the extreme surface of the monolayers is entirely covered by quaterthiophene units after typical adsorption times of 12 h. PM-IRRAS spectra allow to follow the orientation of molecules within the monolayer versus adsorption time. It is shown that the long axis of quaterthienyl groups stand slightly tilted with respect to the perpendicular. In addition, interfacial reactions of the SAM layer with a model molecule, the end-capped terthiophene, were electrochemically induced via the formation of radical cations. The number of grafted molecules that depends on the 4T film structure is discussed in regard to the 4T moiety reactivity.