Anodic grafting of organic groups on the silicon surface

Anodic treatment in an organic anhydrous electrolyte has been explored as a route for grafting organic groups on the hydrogenated silicon surface. Substitution of the hydrogen by organic groups first requires breaking of the SiH bonds. This breaking may be realised, either through direct potential activation, or more often through anodic generation of organic radicals followed by reaction of the radicals with the surface, leading to hydrogen abstraction from the SiHs. A second radical may then be grafted on the remaining silicon dangling bond. This method has been explored for alkyl, alkenyl, alkynyl, and aryl radicals by starting from Grignard electrolytes, and also for halogeno and cyano radicals by starting from anhydrous acetonitrile electrolytes. Fast grafting is generally obtained. However, the reaction is self-limiting only for the most inert radicals such as alkyl and ethynyl. In the case of more reactive radicals, side reactions, such as electropolymerisation on the silicon surface, may be observed.