Structured polymer brushes by AFM lithography.

Structured polymer surfaces have gained increased attention in various research fields during the past few years. By structuring of polymer surfaces, in particular of polymer brushes, functional surfaces with defined properties, for example for the study of cell adhesion and of cell alignment, have been prepared. Moreover, patterning of polymer brushes allows the alteration and control of their wetting properties. Patterned polymer brushes can be obtained by different methods including top–down approaches such as electron beam chemical lithography (EBCL), photolithography, dip-pen lithography, and microcontact printing (mCP) and bottom–up methods such as Langmuir–Blodgett (LB) lithography. These methods mainly rely on a ‘‘grafting from’’ approach in which lithography is used to site-selectively initiate a polymerization process or to site-selectively install a polymerization initiator. In the latter case, subsequent polymerization eventually leads to structured polymer brushes. In addition, studies on the mechanical manipulation (nanoscratching/nanoshaving) of polymer films prepared by spin-coating, as well as selfassembled monolayers (SAMs) and the nanowear of different polymer film architectures, have been performed, and even heated atomic force microscopy (AFM) tips have been used for lithographic processes on polymer films. Herein, we present an alternative approach to obtain structured polymer brushes by mechanical nanoscratching