Taddei Sara

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Supervisors: Prof. Giancarlo Galli; Dr. Elisa Martinelli

Title: Macromolecular engineering of nanostructured polymer film surfaces

Lithography of directed self-assembly of diblock copolymers offers a unique route to generate nanoscale periodically structured materials.
Three synthetically controlled variables determine the morphology: the overall degree of polymerization, the block−block interaction parameter (X), and the relative volume fraction of each block. For pattern transfer applications, the interfacial interaction with the substrate should be taken into account as a fourth variable to effect orientation of the nanoscopic structures in thin block copolymer films.
Following the above rationale, in this PhD work dual-purpose block copolymers were prepared via ATRP. These copolymers are constituted by a polystyrene first block and a second block consisting of a gradient sequence of methyl methacrylate and 2-(perfluorohexyl)ethyl acrylate units. In addition, a hydroxyl group is placed at one polymer terminus.
Consequently, from one hand these materials can be grafted to an activated silicon surface, using a simple thermal treatment involving the Rapid Thermal Processing (RTP) approach, thus providing control over the substrate surface nature. On the other hand, they can be employed as high-self-assembling materials once a neutral layer is deposited on the silicon surface to fully mask the underlying substrate.
Both uses will be presented with reference to the influence of the composition and molar mass of the two blocks