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ABSTRACT
This article describes a new synthesis pathway based on emulsions allowing for the preparation of narrow size distributed thermo-responsive microcapsules constituted of a wax core, i.e. a crystallized oil, surrounded by a silica shell obtained through the mineralization of the oil-water interface. Under heating, the inner wax expands during the liquefaction process and the shell breaks allowing for the liquid oil release. Such capsules, the rupture of which is provoked by an external stimulus, belong to the class of smart materials. The temperature, at which the shell breaks and the content released, is fixed by the choice of oil whereas the capsules’ size is determined by the formulation of the so-called Pickering or solid-stabilized emulsion.
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Read the articleAUTHORS
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Véronique SCHMITT: Doctorate in physical sciences from the University of Strasbourg - Director of Research at the Centre National de la Recherche Scientifique (CNRS) Centre de Recherche Paul Pascal (CRPP) – UPR 8641 Bordeaux
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Mathieu DESTRIBATS: Doctoral student at Bordeaux University - Engineer, École nationale supérieure de chimie et de physique de Bordeaux - Doctoral student at the Centre de recherche Paul Pascal (UPR CNRS 8641) et Transferts Écoulements Fluides Énergétiques (TREFLE) – UMR 8508 Bordeaux
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Rénal BACKOV: Doctorate in chemical sciences from the University of Montpellier - Professor, University of Bordeaux – Centre de recherche Paul Pascal (CRPP) UPR 8641 Bordeaux
INTRODUCTION
These microcapsules consist of a core of wax, i.e. crystallized oil, surrounded by a silica shell obtained by mineralization of the water-oil interface. On heating, the oil becomes liquid, and this change of state is accompanied by a volumetric expansion that causes the rigid, brittle shell to break, releasing the oil. These capsules, whose rupture is triggered by an external stimulus, belong to the class of so-called "intelligent" materials. The temperature at which the shell ruptures, and thus the contents are released, is determined by the melting temperature of the oil, while the size of the capsules is set by the formulation of so-called Pickering emulsions, i.e. stabilized by colloidal particles.
These microcapsules are made of a wax core, that is to say a crystallised oil, surrounded by a silica shell obtained by mineralization of the oil-water interface. Under heating, the inner wax expands during the liquefaction and the shell breaks leading to the liquid oil release. Such capsules, that allow triggered deliverance provoked by an external stimulus, belong to the class of smart materials. The temperature, at which the shell breaks and the content is released, is fixed by the oil choice whereas the capsule size is determined by formulation of the so-called Pickering or solid-stabilized emulsion.
Pickering emulsions, crystallizable oil, mineralization, sol-gel chemistry, capsules, induced release.
solid-stabilized or Pickering emulsions, crystallisable oil, mineralization, sol-gel chemistry, capsules, thermotriggered release.
Field: psycho-chemistry, soft matter, soft chemistry
Degree of technology dissemination: emerging Technologies involved: emulsion, mineralization
Applications: pharmaceuticals, cosmetics, agri-food, phytosanitary, stationery...
Main French players: CNRS, Université de Bordeaux
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Unit operations. Chemical reaction engineering
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Core-shell microcapsules with thermally stimulated release
Context
Bibliography
Events
World Emulsion Congress 2010 (October 12-14, Lyon) http://www.cme-emulsion.com
European Colloid and Interface Society conference (September 4-9, 2001, Berlin) http://www.ecis2011.org
Directory
Laboratories – Design offices – Schools – Research centers (non-exhaustive list)
Paul-Pascal Research Center http://www.crpp-bordeaux.cnrs.fr/
Particular Vectorization Engineering (Inserm) http://www.gepea.fr/
Biogalenic Pharmacy...
Patents
Pressure sensitive record material US 2712507.
New core-shell objects with thermostimulated delivery and method of preparation FR 0955417
Crystallizable oil compositions stabilized by colloidal particles WO 2005/082507A1.
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