Polymer brush-assisted microcontact printing: using a tailor-made polydimethylsiloxane (PDMS) stamp for precise patterning of rough surfaces

Abstract

Rough, capillary-active surfaces remain demanding substrates for microcontact printing (μCP), as the diffusive mobility of the ink thereon drastically limits the printing resolution. To reduce ink smearing, we developed polymer-supported μCP, which includes a stamp with a polymer brush-decorated surface. The ink molecules are thereby bound to the stamp-bound brush matrix, from where they may be transferred to the substrate, which exclusively occurs during the contact of both interfaces. Conventionally, Sylgard 184-based polydimethylsiloxane (PDMS) stamps are used for μCP. The material's surface must be functionalized in a multi-step procedure for the protocol. In addition, Sylgard comes along with the drawback of a persistent leakage of oligomeric PDMS (oPDMS), which can contaminate the substrate. To circumvent these problems, we developed a novel stamp material that (i) enables a straightforward polymer grafting and (ii) shows a low tendency for oPDMS leakage. We prepared the stamp with a commercially available amino-functionalized PDMS prepolymer and a polymeric crosslinker that can be used for a controlled photoiniferter reversible addition and fragmentation chain transfer (PI-RAFT) polymerization. The prepared stamp shows elastic properties in the relevant strain region, is compatible with brush formation, and has been demonstrated to be suitable for transferring precise patterns on rough capillary-active oxide surfaces.