title: Dynamic perspective on the function of thermoresponsive nanopores from in situ AFM and ATR-IR investigations.
abstract: This article describes the morphological and chemical characterization of stimuli-responsive functionalized silicon surfaces provided in parallel by atomic force spectroscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) enhanced by the single-beam sample reference attenuated total reflection method (SBSR-ATR). The stimuli-responsive behavior of the surfaces was obtained by grafting-to in melt carboxyl-terminated poly-N-isopropylacryl amides (PNIPAAM) with different degree of polymerization (DP) on epoxide-functionalized silicon substrates. The unprecedented real time and in situ physicochemical insight into the temperature-triggered response of the densely packed superficial brushes allowed for the selection of a PNIPAAM with a specific DP as a suitable polymer for the fabrication of silicon membranes exhibiting switchable nanopores. The fabrication process combines the manufacture of nanoporous silicon surfaces and their subsequent chemical functionalization by the grafting-to in melt of the selected polymer. Then, relevant information was obtained in what concerns the chemical modifications behind the topographical changes that drive the functioning of PNIPAAM-based hybrid nanovalves as well as the timescale on which the opening and closing of the nanopores occur.
authors.affiliation: Centre Suisse d'Electronique et de Microtechnique SA, Rue Jaquet Droz 1, CH-2000 Neuchâtel, Switzerland. ana-maria.popa@empa.ch
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Popa
authors.forename: Silvia
authors.initials: S
authors.lastname: Angeloni
authors.forename: Thomas
authors.initials: T
authors.lastname: Bürgi
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hubbell
authors.forename: Harry
authors.initials: H
authors.lastname: Heinzelmann
authors.forename: Raphaël
authors.initials: R
authors.lastname: Pugin
mesh_terms: D018625:Microscopy, Atomic Force / Q000379:methods*; D058608:Nanopores; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013499:Surface Properties