Adsorption of photoresponsive surfactants at solid-liquid interfaces
- We report on the adsorption kinetics of azoben-zene-containing surfactants on solid surfaces of different hydrophobicity. The understanding of this processes is of great importance for many interfacial phenomena that can be actuated and triggered by light, since the surfactant molecules contain a photoresponsive azobenzene group in their hydrophobic tail. Three surfactant types are studied, differing in the spacer connecting the headgroup and the azobenzene unit by between 6 and 10 CH2 groups. Under irradiation with light of a suitable wavelength, the azobenzene undergoes reversible photoisomerization between two states, a nonpolar trans-state and a highly polar cis-state. Consequently, the surfactant molecule changes its hydrophobicity and thus affinity to a surface depending on the photoisomerization state of the azobenzene. The adsorption behavior on hydrophilic (glass) and hydrophobic (TeflonAF) surfaces is analyzed using quartz crystal microbalance with dissipation (QCM-D) and zeta-potential measurements. At equilibrium, theWe report on the adsorption kinetics of azoben-zene-containing surfactants on solid surfaces of different hydrophobicity. The understanding of this processes is of great importance for many interfacial phenomena that can be actuated and triggered by light, since the surfactant molecules contain a photoresponsive azobenzene group in their hydrophobic tail. Three surfactant types are studied, differing in the spacer connecting the headgroup and the azobenzene unit by between 6 and 10 CH2 groups. Under irradiation with light of a suitable wavelength, the azobenzene undergoes reversible photoisomerization between two states, a nonpolar trans-state and a highly polar cis-state. Consequently, the surfactant molecule changes its hydrophobicity and thus affinity to a surface depending on the photoisomerization state of the azobenzene. The adsorption behavior on hydrophilic (glass) and hydrophobic (TeflonAF) surfaces is analyzed using quartz crystal microbalance with dissipation (QCM-D) and zeta-potential measurements. At equilibrium, the adsorbed surfactant amount is almost twice as large on glass compared to TeflonAF for both isomers. The adsorption rate for the trans-isomers on both surfaces is similar, but the desorption rate of the trans-isomers is faster at the glass-water interface than at the Teflon-water interface. This result demonstrates that the trans-isomers have higher affinity for the glass surface, so the trans-to-cis ratios on glass and TeflonAF are 80/1 and 2/1, respectively, with similar trends for all three surfactant types.…
Author details: | Maren Umlandt, David FeldmannORCiDGND, Emanuel SchneckORCiDGND, Svetlana SanterORCiDGND, Marek BekirORCiDGND |
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DOI: | https://doi.org/10.1021/acs.langmuir.0c02545 |
ISSN: | 0743-7463 |
ISSN: | 1520-5827 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/33182998 |
Title of parent work (English): | Langmuir |
Publisher: | American Chemical Society |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Date of first publication: | 2020/11/13 |
Publication year: | 2020 |
Release date: | 2023/06/28 |
Volume: | 36 |
Issue: | 46 |
Number of pages: | 10 |
First page: | 14009 |
Last Page: | 14018 |
Funding institution: | Priority Program 1726 "Microswimmers-From Single Particle Motion to; Collective Behaviour", Germany; DFGGerman Research Foundation; (DFG)European Commission [SA1657/8-2]; Helmholtz Graduate School on; Macromolecular Bioscience (Teltow, Germany) |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Peer review: | Referiert |