Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 64: Oxides and Interfaces: Adsorption II

O 64.2: Talk

Wednesday, March 9, 2016, 15:15–15:30, H6

Effects of Flexibility and Entropy on the Adsorption and Growth of Functional Molecules — •David Gao¹, Julian Gaberle¹, Matthew Watkins², Filippo Federici Canova³, Christian Loppacher⁴, Laurent Nony⁴, Ania Amrous⁴, Franck Bocquet⁴, Franck Para⁴, and Alexander Shluger^{1, 5} — ¹University College London, London, UK — ²University of Lincoln, Lincoln, UK — ³Aalto University, Espoo, Finland — ⁴Aix-Marseille University CNRS, Marseille, France — ⁵WPI-AIMR Tohoku University, Sendai, Japan

In this work we combined noncontact atomic force microscopy (NCAFM) experiments and theoretical calculations to study the effects of molecular flexibility on the adsorption and self-assembly of organic molecules on KCl(001).

Rigid 1,3,5-tri-(4-cyano-4,4 biphenyl)-benzene (TCB) and flexible 1,4-bis(cyanophenyl)-2,5-bis(decyloxy)benzene (CDB) molecules were synthesized, deposited onto a KCl (110) surface, and imaged using NCAFM. Both molecules were observed to form ordered monolayer structures at room temperature. However, the dewetting properties and growth modes of these two molecules were qualitatively different. We performed density functional theory (DFT) and classical molecular dynamics (MD) calculations to consider both enthalpic and entropic contributions to adsorption energy. Our results show that entropic effects are significant for flexible molecules (such as CDB) and can have a pronounced effect on the mechanisms of self-assembly and structural stability.