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Ultrasmall Nanocapsules Obtained by Controlling Ostwald Ripening
Author(s) -
DoanNguyen Thao P.,
Jiang Shuai,
Koynov Kaloian,
Landfester Katharina,
Crespy Daniel
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202103444
Subject(s) - ostwald ripening , nanocapsules , miniemulsion , chemical engineering , microemulsion , pulmonary surfactant , materials science , chemistry , nanoparticle , nanotechnology , polymerization , organic chemistry , polymer , engineering
Abstract We describe here a method to synthesize ultrasmall nanocapsules with a diameter of 6 nm, exhibiting a well‐defined core–shell morphology. Remarkably, the nanocapules are synthesized in a miniemulsion process without the need of large amounts of surfactant as commonly used in the microemulsion process. Ultrasmall nanocapsules with an oil core and a silica shell are formed by the concurrent processes of a sol–gel reaction and Ostwald ripening. Using solvents with different water solubilities and alkoxysilanes with different reactivities, we demonstrate that sizes of obtained nanocapsules depend on the ripening rate and alkoxysilane conversion rate. The method can be also used for encapsulating natural oils such as peppermint oil and limonene. This work shows that the Ostwald ripening phenomenon can be employed beneficially for the preparation of very small colloids.