A critical bottleneck for the widespread use of single layer graphene is the absence of a facile method of chemical modification which does not diminish the outstanding properties of the two-dimensional sp(2) network. Here, we report on the direct chemical modification of graphene by photopolymerization with styrene. We demonstrate that photopolymerization occurs at existing defect sites and that there is no detectable disruption of the basal plane conjugation of graphene. This method thus offers a route to define graphene functionality without degrading its electronic properties. Furthermore, we show that photopolymerization with styrene results in self-organized intercalative growth and delamination of few layer graphene. Under these reaction conditions, we find that a range of other vinyl monomers exhibits no reactivity with graphene. However, we demonstrate an alternative route by which the surface reactivity can be precisely tuned, and these monomers can be locally grafted via electron-beam-induced carbon deposition on the graphene surface.

The self-initiated photografting and photopolymerization (SIPGP) of styrene, methyl methacrylate, and tert-butyl methacrylate on structured self-assembled monolayers (SAMs) of electron beam cross-linked omega-functionalized biphenylthiols SAMs on gold was investigated. Polymer brushes with defined thickness can be prepared on crosslinked benzyl-, phenyl-, hydroxyl-, and amino-functionalized SAMs, whereas non-cross-linked SAM regions desorb from the surface during the SIPGP process. By the preparation of brush gradients on different functionalized SAMs, it was demonstrated that the resulting polymer brush layer thickness is determined by the locally applied electron beam dosage. Defined micro-nanostructured polymer brush patterns can be prepared down to a size of 50 nm. Finally, it was shown that polymer brushes obtained by the SIPGP process have a branched architecture.

The surface-initiated photopolymerization (SIPP) of vinyl monomers on structured self-assembled monolayers, as defined by two-dimensional (2D) initiator templates for polymer growth, is investigated. The 2D templates are prepared by electron-beam chemical lithography (EBCL) of 4'-nitro-4-mercaptobiphenyl (NBT) and chemical conversion to an asymmetric azo initiator (4'-azomethylmalonodinitrile-1,1'-biphenyl-4-thiol). Ex situ kinetic studies of the SIPP process reveal a linear increase in the thickness of the polymer layer with the irradiation/polymerization time. The effect of the applied electron dosage during the EBCL process upon the final thickness of the polymer layer is also studied. The correlation between the electron-induced conversion of the 4'-nitro to the 4'-amino group and the layer thickness of the resulting polymer brush indicates that the polymer-brush grafting density can be directly controlled by the EBCL process. NBT-based template arrays are used for the combinatorial study of the influence of the lateral structure size and the irradiation dosage on the morphology of the resulting polymer-brush layer. Analysis of the array topography reveals the dependence of the thickness of the dry polymer layer on both electron dosage and structure size. This unique combination of EBCL as a lithographic technique to locally manipulate the surface chemistry and SIPP to amplify the created differences allows the preparation of defined polymer-brush layers of controlled morphologies.