Surface-relief gratings in halogen-bonded polymer-azobenzene complexes

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2017-11-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
1-11
Series
Molecules, Volume 22, issue 11
Abstract
In recent years, supramolecular complexes comprising a poly(4-vinylpyridine) backbone and azobenzene-based halogen bond donors have emerged as a promising class of materials for the inscription of light-induced surface-relief gratings (SRGs). The studies up to date have focused on building supramolecular hierarchies, i.e., optimizing the polymer-azobenzene noncovalent interaction for efficient surface patterning. They have been conducted using systems with relatively low azobenzene content, and little is known about the concentration dependence of SRG formation in halogen-bonded polymer-azobenzene complexes. Herein, we bridge this gap, and study the concentration dependence of SRG formation using two halogen-bond-donating azobenzene derivatives, one functionalized with a tetrafluoroiodophenyl and the other with an iodoethynylphenyl group. Both have been previously identified as efficient molecules in driving the SRG formation. We cover a broad concentration range, starting from 10 mol % azobenzene content andgoing all the way up to equimolar degree of complexation. The complexes are studied as spin-coated thin films, and analyzed by optical microscopy, atomic force microscopy, and optical diffraction arising during the SRG formation. We obtained diffraction efficiencies as high as 35%, and modulation depths close to 400 nm, which are significantly higher than the values previously reported for halogen-bonded polymer-azobenzene complexes.
Description
Keywords
Azobenzene, Halogen bonding, Photoresponsive, Supramolecular, Surface-relief grating
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Citation
Stumpel , J E , Saccone , M , DIchiarante , V , Lehtonen , O , Virkki , M , Metrangolo , P & Priimagi , A 2017 , ' Surface-relief gratings in halogen-bonded polymer-azobenzene complexes : A concentration-dependence study ' , Molecules , vol. 22 , no. 11 , 1844 , pp. 1-11 . https://doi.org/10.3390/molecules22111844