Hydrophobic-core microcapsules and their formation
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsLuz M. Calle, Wenyan Li, Jerry W. Buhrow, Scott T. Jolley
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Abstract
Hydrophobic-core microcapsules and methods of their formation are provided. A hydrophobic-core microcapsule may include a shell that encapsulates a hydrophobic substance with a core substance, such as dye, corrosion indicator, corrosion inhibitor, and/or healing agent, dissolved or dispersed therein. The hydrophobic-core microcapsules may be formed from an emulsion having hydrophobic-phase droplets, e.g., containing the core substance and shell-forming compound, dispersed in a hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell.
Claims23
A method of forming hydrophobic-core microcapsules comprising:
- forming a hydrophobic phase including a pre-polymer or monomer, a cross-linking agent, at least one active substance, wherein said at least one active substance is a corrosion indicator, a corrosion inhibitor, or combination thereof, an optional co-solvent, and a hydrophobic substance;
- forming a hydrophilic phase;
- mixing the hydrophobic phase with the hydrophilic phase to create and disperse droplets of the hydrophobic phase within the hydrophilic phase to form an emulsion;
- initiating a reaction at an interface of the hydrophilic phase and the hydrophobic phase to form a solid shell encapsulating the hydrophobic phase forming hydrophobic-core microcapsules, wherein said solid shell includes a shell wall comprising a compound having one or more chemical bonds that are broken down when contacted with an alkali produced during a corrosion reaction causing the release of the hydrophobic phase, wherein said alkali has a pH above about 8.
A method of forming hydrophobic-core microcapsules comprising:
- forming a first hydrophobic phase including at least one active substance and at least one surfactant in the absence of a cross-linking agent and in the absence of a pre-polymer;
- forming a hydrophilic phase;
- mixing the first hydrophobic phase with the hydrophilic phase to form an emulsion comprising droplets of the first hydrophobic phase dispersed in the hydrophilic phase;
- forming a second hydrophobic phase including a cross-linking agent comprising one or more ester groups and a pre-polymer in the absence of any active substance;
- mixing the second hydrophobic phase to said emulsion to form droplets including the first hydrophobic phase and the second hydrophobic phase dispersed in the hydrophilic phase;
- and
- initiating a reaction at an interface of the hydrophilic phase and droplets including the first and second hydrophobic phases to form a single shell encapsulating the first and second hydrophobic phases forming hydrophobic-core microcapsules, wherein said single shell includes a shell wall comprising a compound having one or more chemical bonds that are broken down when contacted with an alkali produced during a corrosion reaction causing the release of the first and second hydrophobic phases, wherein said alkali has a pH above about 8.
Dependencies are inferred from the claim text.