Reactive block copolymers for patterned surface immobilization with sub-30 nm spacing
Phase-segregating block copolymers are powerful platforms for nanofabrication, particularly when employed as lithographic mask precursors. Surface-reactive polymeric films with distinct sub-30 nm domains are also proposed as covalent docking platforms for scalable, high-resolution molecular patterned immobilization. Here, the well-known self-assembling polystyrene-block-polyisoprene system is the starting point to produce a small library of derivatives with distinct reactive pendant groups (halide, azide, pentafluorophenylalkyl) by nitroxide-mediated radical polymerization. We find that controlling film thickness is crucial to obtain a perpendicular lamellar morphology and that the presence of the functional groups has a limited impact on self-assembly, yet may influence characteristic domain dimensions. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM) are utilized in concert to assess the phase behavior of the polymers and the surface features of the nanostructures. As a proof-of-concept for the surface reactivity, click chemistry-driven immobilization of a model water-soluble polymer is evidenced by X-ray photoelectron spectroscopy (XPS) and preservation of the underlying morphology is investigated by AFM.