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Mahmoudvand M, Vatanparast H, Javadi A, Kantzas A, Burns S, Dolgos M, Miller R, Bahramian A. Evaluation of Interfacial Structure of Self-Assembled Nanoparticle Layers: Use of Standard Deviation between Calculated and Experimental Drop Profiles as a Novel Method. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:2130-2145. [PMID: 38214546 DOI: 10.1021/acs.langmuir.3c03081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
The self-assembly of nanoparticles (NPs) at interfaces is currently a topic of increasing interest due to numerous applications in food technology, pharmaceuticals, cosmetology, and oil recovery. It is possible to create tunable interfacial structures with desired characteristics using tailored nanoparticles that can be precisely controlled with respect to shape, size, and surface chemistry. To address these functionalities, it is essential to develop techniques to study the properties of the underlying structure. In this work, we propose an experimental approach utilizing the standard deviation of drop profiles calculated by the Laplace equation from experimental drop profiles (STD), as an alternative to the Langmuir trough or precise microscopic methods, to detect the initiation of closely packed conditions and the collapse of the adsorbed layers of CTAB-nanosilica complexes. The experiments consist of dynamic surface/interfacial tension measurements using drop profile analysis tensiometry (PAT) and large-amplitude drop surface area compression/expansion cycles. The results demonstrate significant changes in STD values at the onset of the closely packed state of nanoparticle-surfactant complexes and the monolayer collapse. The STD trend was explained in detail and shown to be a powerful tool for analyzing the adsorption and interfacial structuring of nanoparticles. Different collapse mechanisms were reported for NP monolayers at the liquid/liquid and air/liquid interfaces. We show that the interfacial tension (IFT) is solely dependent on the extent of interfacial coverage by nanoparticles, while the surfactants regulate only the hydrophobicity of the self-assembled complexes. Also, the irreversible adsorption of nanoparticles and the increasing number of adsorbed complexes after the collapse were observed by performing consecutive drop surface compression/expansion cycles. In addition to a qualitative characterization of adsorption layers, the potential of a quantitative calculation of the parameter STD such as the number of adsorbed nanoparticles at the interface and the distance between them at different states of the interfacial layer was discussed.
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Affiliation(s)
- Mohsen Mahmoudvand
- Department of Chemical and Petroleum Engineering, University of Calgary, T2N 1N4 Calgary, Alberta, Canada
| | - Hamid Vatanparast
- Chemical Engineering Department, College of Engineering, University of Tehran, 1417614411 Tehran, Iran
| | - Aliyar Javadi
- Chemical Engineering Department, College of Engineering, University of Tehran, 1417614411 Tehran, Iran
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - Apostolos Kantzas
- Department of Chemical and Petroleum Engineering, University of Calgary, T2N 1N4 Calgary, Alberta, Canada
| | - Stuart Burns
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T2N 1N4 Calgary, Alberta, Canada
| | - Michelle Dolgos
- Department of Chemistry, University of Calgary, 2500 University Drive NW, T2N 1N4 Calgary, Alberta, Canada
| | - Reinhard Miller
- Technical University Darmstadt, Institute of Condensed Matter Physics, Hochschulstraße 8, D-64289 Darmstadt, Germany
| | - Alireza Bahramian
- Chemical Engineering Department, College of Engineering, University of Tehran, 1417614411 Tehran, Iran
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