Synthesis of surface‐initiated polymer brushes using macro‐initiators

The synthesis of polymer brushes using surface‐adsorbed macro‐initiators is briefly reviewed, with particular emphasis being placed on the combination of atom transfer radical polymerisation with polyelectrolytic macro‐initiators. The latter contain 2‐bromoester initiator groups and can be readily prepared with either cationic or anionic character from (co)polymer precursors. Such macro‐initiators offer convenient functionalisation of a wide range of colloidal and planar charged surfaces such as silica, mica, alumina or tin(IV) oxide, since electrostatic adsorption occurs rapidly from aqueous solution at room temperature. A wide range of hydrophilic methacrylic polymer brushes have been grown from these macro‐initiators, offering potential applications in surface lubricity and tribology, tuneable surface (de)wetting and cell detachment. In some cases surface degrafting can occur if thicker polymer brushes are targeted. However, this problem can be circumvented if pairs of oppositely charged polyelectrolytic macro‐initiators are used to build up ionically crosslinked multilayers via layer‐by‐layer self‐assembly. This facile approach to surface functionalisation appears to be steadily growing in popularity and has now been adopted by a number of research groups in several countries.