Comb and dendrigraft polystyrenes with ferrocenyl units at the periphery: Synthesis and electrochemical properties

Polystyrene (PS) combs and dendrigrafts bearing di(hydroxymethyl) group termini at each branch end were used as starting materials for the preparation of branched and hyperbranched polymer structures with ferrocenyl moieties at their periphery. Quantitative acetalization of the 1,3-propanol ends using carboxaldehyde ferrocene yields polymers with one ferrocenyl moiety per branch terminus. By varying the size of the different macromolecular building blocks used in the preparation of the hyperbranched polymers, in particular the (DPn) over bar of the PS blocks forming the external branches, a series of ferrocenyl-functionalized polystyrene combs and dendrigrafts was prepared. Their electrochemical properties were studied by cyclic voltammetry in organic solution and compared with the corresponding alpha-functional linear PS. Results show that all ferrocenyl groups in dendrigrafts are available and participate to the oxidation-reduction cycles while only a small fraction of the ferrocene groups is active in combs and linear PS.