Structured polymer brushes on silicon carbide

A straightforward method is presented for the preparation of homogeneous as well as structured polymer brushes on SiC substrates. The self-initiated photografting and photopolymerization (SIPGP) of styrene and N,N-dimethylaminoethyl methacrylate (MAEMA) allows the preparation of polymer brush layers directly and selectively onto C-OH terminated (0001) 6H-SiC surfaces in a single step reaction. In contrast, the analogous reaction on Si-OH terminated (0001) 6H-SiC does not occur. The reactivity contrast between Si-OH and C-OH terminated crystal faces for SIPGP was studied using the density functional theory method which showed a higher SiO-H bond dissociation energy for hydrogen abstraction on the Si-polar relative to the C-polar crystal face. Furthermore, structured polymer brushes on the submicrometer scale could be prepared by the carbon templating (CT) technique on Si-OH terminated (0001) 6H-SiC surfaces. First, an ultrathin template layer was formed by electron beam induced carbon deposition (EBCD) on SiC by means of a focused electron beam. Amplification of the template by SIPGP resulted in polymer brush structures with controlled three-dimensional shapes. The effect of the applied electron dose as well as the initial lateral structure size on the brush layer morphology was investigated.