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Nano-Structure Formation Driven By Local Protonation Of Polymer Thin Films, Carsten Maedler, Harald Graaf, Mingdi Yan, Andres H. La Rosa
Nano-Structure Formation Driven By Local Protonation Of Polymer Thin Films, Carsten Maedler, Harald Graaf, Mingdi Yan, Andres H. La Rosa
Physics Faculty Publications and Presentations
We report the creation of nano-structures via Dip Pen Nanolithography by locally exploiting the mechanical response of polymer thin films to an acidic environment. Protonation of cross linked poly(4-vinylpyridine) (P4VP) leads to a swelling of the polymer. We studied this process by using an AFM tip coated with a pH 4 buffer. Protons migrate through a water meniscus between tip and sample into the polymer matrix and interact with the nitrogen of the pyridyl group forming a pyridinium cation. The increase in film thickness, which is due to Coulomb repulsion between the charged centers, was investigated using Atomic Force Microscopy. …