TY - JOUR
T1 - Investigation of the Mechanism of SiO2Particle and Capsule Formation at the Oil-Water Interface of Dye-Stabilized Emulsions
AU - Sihler, Susanne
AU - Amenitsch, Heinz
AU - Lindén, Mika
AU - Ziener, Ulrich
N1 - Funding Information:
We gratefully acknowledge financial support by the German Science Foundation DFG through the project ZI567/9-1 and the opportunity to perform the SAXS measurements at the German Synchrotron Radiation Facility DESY, Hamburg. We thank A. Chumakov for assistance in using beamline P03 at the light source PETRA III.
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/8/16
Y1 - 2022/8/16
N2 - In a previous contribution we described the formation of silica nanostructures in dye-stabilized nanoemulsions from tetraethyl orthosilicate droplets in water. Depending on the type of dye, either capsules (crystal violet, CV) or nanoparticles (congo red, CR) are formed. The thorough study of the sol-gel process uses a combination of time- and/or temperature-resolved small-angle X-ray scattering, transmission electron microscopy, and 1H NMR spectroscopy to elucidate the detailed kinetics and mechanism of structure formation. In both cases, small nuclei of 1.5-2 nm are formed, followed by either a fast cluster-cluster (CV) or a much slower monomer-cluster aggregation (CR). The former leads to a cross-linked network and finally to patchy capsules, while the latter leads to individual nanoparticles (SNPs). From an Avrami plot it can be deduced that the SNPs are formed by an interface-controlled one-dimensional growth process. The mechanisms are based on the different local environments at the oil-water interface, which is either slightly acidic (CV) or fairly basic (CR). The kinetics differ by a factor between 3 and 20 and are presumably caused by the different mobility of the catalyzing species H+ or OH-.
AB - In a previous contribution we described the formation of silica nanostructures in dye-stabilized nanoemulsions from tetraethyl orthosilicate droplets in water. Depending on the type of dye, either capsules (crystal violet, CV) or nanoparticles (congo red, CR) are formed. The thorough study of the sol-gel process uses a combination of time- and/or temperature-resolved small-angle X-ray scattering, transmission electron microscopy, and 1H NMR spectroscopy to elucidate the detailed kinetics and mechanism of structure formation. In both cases, small nuclei of 1.5-2 nm are formed, followed by either a fast cluster-cluster (CV) or a much slower monomer-cluster aggregation (CR). The former leads to a cross-linked network and finally to patchy capsules, while the latter leads to individual nanoparticles (SNPs). From an Avrami plot it can be deduced that the SNPs are formed by an interface-controlled one-dimensional growth process. The mechanisms are based on the different local environments at the oil-water interface, which is either slightly acidic (CV) or fairly basic (CR). The kinetics differ by a factor between 3 and 20 and are presumably caused by the different mobility of the catalyzing species H+ or OH-.
UR - http://www.scopus.com/inward/record.url?scp=85136047175&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.2c00304
DO - 10.1021/acs.langmuir.2c00304
M3 - Article
C2 - 35925782
AN - SCOPUS:85136047175
VL - 38
SP - 9741
EP - 9750
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 32
ER -