Scanning Thermal Lithography for Nanopatterning of Polymers: Transient Heat Transport and Thermal Chemical Functionalization Across the Length Scales

The research described in this Thesis comprises the development of Scanning Thermal Lithography (SThL) as an alternative approach for the spatially controlled, highly localized thermal chemical surface modification of polymer films for the development of e.g. (bio)sensors. In the Thesis, the range of thermal transport from heated AFM probes in contact with polymer surfaces is assessed. Proximity effects of thermally conductive substrates for supported thin polymer films on the calibrated probe tip-sample interface temperature for heated AFM probes are elaborated. Having established the basic needs for the development of SThL in terms of heatable AFM probes, the well established polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) polymer film platform was explored for utilization in thermochemical surface activation reactions, starting with Reactive Imprint Lithography (RIL) at the macroscopic length scale. RIL comprises the topographical patterning and the simultaneous thermal deprotection of the tert-butyl ester protected carboxylic acid groups in the PtBA block. The successful thermal chemical functionalization followed by the wet chemical surface derivatization with e.g. poly(ethylene glycol), was followed by the introduction of SThL on the PS-b-PtBA film platforms to enable thermal chemical surface functionalization at the sub-micrometer length scale. Disadvantage of the block copolymer film platform were the observed thermomechanical surface deformations, exceeding 400 nm in diameter, after SThL. Therefore crosslinked tert-butyl (meth)acrylate polymer films were prepared and their thermal decomposition mechanism was analyzed in detail followed by their utilization in SThL. Overall SThL is shown to be a promising nanotechnology tool for the thermal chemical surface modification with sub 50 nm spatial resolution.