Surface-grafted Hyperbranched Polymers by Self- Condensing Vinyl (co)polymerization via Atrp

Introduction Highly branched polymers play an increasingly important role in interface and surface sciences, since their distinctive chemical and physical properties can be used advantageously as functional surfaces and as interfacial materials. Hyperbranched polymers grafted onto surfaces have also become a field of growing interest. Depending upon the substrates, it can be divided into 3D, 2D, and 1D hybrids, which correspond to products grafted on spherical particles, planar surfaces, and linear polymers, respectively. Previously, synthesis of dendrimers and hyperbranched polymers grafted onto surfaces has been mainly conducted by “grafting to” techniques.1,2 A series of repeated "grafting from" steps have been also employed.3 However, both approaches have the disadvantage that many tedious synthetic steps are necessary to reach the defined surface structures. We describe here a novel synthetic concept for preparing hyperbranched (meth)acrylates on 2D and 3D surfaces in which a silicon wafer or silica nanoparticles grafted with an initiator layer composed of an -bromoester fragment were used for self-condensing vinyl polymerization (SCVP) via atom transfer radical polymerization (ATRP) (Scheme 1). Surface-initiated self-condensing vinyl copolymerization (SCVCP) was also applied as a method for the synthesis of highly branched polymers grafted from surfaces. In contrast, surface-initiated ATRP resulted in the preparation of linear polymer brushes.