AFM characterization of micro-contact printed self-assembled monolayers of alkanethiols

May 18, 2016, 2:45 PM
8h 15m
Pand

Pand

Speaker

Mrs ShovaHasselt University NEUPANE

Description

Self-assembled thiol monolayers (SAMs) are molecular assemblies of organic constituents formed spontaneously by the adsorption process of thiol molecules in liquid or vapor phase on metal or metal oxide surfaces [1]. On the one hand, chemisorption of the adsorbate head group onto metal surfaces at the metal-SAM nano-interface leads to a strong sulfur-metal bond, on the other hand, interactions including van der Waals and hydrophobic forces exist among backbone chains, ensuring an efficient packing of the monolayer and contributing to stabilize the structures with increasing chain length. Thiol SAMs can be prepared with a wide variety of terminal groups (i.e. the group opposite to the sulfur moiety) yielding surfaces with tailored hydrophilic- or hydrophobic properties that can be used as compact platforms for bio- or chemo-sensors [2] or for corrosion inhibition [3,4]. In this work we present a systematic atomic force microscopy (AFM) characterization of well-defined thiol SAM patterns formed onto an ultraflat Au (111) by micro-contact printing [5]. We assess the difference in thickness of different chain length alkanethiol monolayer patterns and evaluate how molecules behave when more complex configurations are used. Concretely, we analyze the organization of alkanethiol molecules in overlapped double patterns, as well as the changes of simple monolayer micropatterns when exposed to a different alkanethiol solution. The work prepares further alloy corrosion studies using well-controlled molecular inhibitor films [1] Love, J. C.; Estroff, L. A.; Kriebel, J. K.; Nuzzo, R. G.; Whitesides, G. M. Self-Assembled Monolayers of Thiolates on Metals as a Form of Nanotechnology, Chem. Rev. 2005, 105, 1103. [2] Jans, K. Stability of mixed PEO-thiol SAMs for biosensing applications, Langmuir 2008, 24, 3949. [3] Pareek, A.; Ankah, G. N.; Cherevko, S.; Ebbinghaus, P.; Mayrhofer, K. J. J.; Erbe, A.; Renner, F. U. Effect of thiol self-assembled monolayers and plasma polymerfilms on dealloying of Cu–Au alloys, RSC Adv. 2013, 3, 6586. [4] Renner, F. U.; Ankah, G. N.; Bashir, A.; Ma, D.; Biedermann, P.; Shrestha, B. R.; Nellessen, M.; Khorashadizadeh, A.; Losada-Pérez, P.; Duarte, M. J.; Raabe, D.; Valtiner, M. Star-shaped crystallographic cracking of localized nanoporous defects, Adv. Mat. 2015, 33, 4877. [5] Whitesides, G. M.; Kumar, K. Features of gold having micrometer to centimeter dimensions can be formed through a combination of stamping with an elastomeric stamp and an alkanethiol “ink” followed by chemical etching, App. Phys. Lett. 1993, 63, 2002.

Primary author

Co-authors

Dr Asif BASHIR (Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany) Frank Uwe RENNER (Hasselt University, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek, Belgium) Patricia LOSADA-PÉREZ (Hasselt University, Institute for Materials Research, Wetenschapspark 1, 3590 Diepenbeek, Belgium) Mr Sébastien VIVEGNIS (Université de Namur)

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