Ceramic encapsulation with controlled layering by use of functionalized silanes
This invention relates to a method for forming hollow silica-based particles suitable for containing one or more active ingredients or for containing other smaller particles which may include one or more active ingredients. The method comprises preparing an emulsion including a continuous phase that is polar or non-polar and a dispersed phase comprising droplets including (i) a polar active ingredient when the continuous phase is non-polar or (ii) a non-polar active ingredient when the continuous phase is polar; and adding a silica precursor to the emulsion such that the silica precursor can be emulsion templated on the droplets to form hollow silica-based particles. The silica precursor has the general formula (I): R 1 x —Si—(OR 2 ) y , wherein R 1 is selected from substituted and unsubstituted alkyl, substituted and unsubstituted aryl, alcohols, amines, amides, aldehydes, acids, esters, and functional groups having an unsaturated carbon-carbon bond, R 2 is an alkyl group, x+y=4, and y=1, 2 or 3. The —OR 2 group is a hydrolyzable organic group that exhibits an ability to form a silicon-oxygen bond chain as a result of hydrolysis and condensation.
1. A method for forming silica-based particles, the method comprising:
(a) preparing an emulsion including a cationic polymer and having a continuous phase that is polar or nonpolar, and a dispersed phase comprising droplets including (i) one or more polar active ingredients when the continuous phase is non-polar or (ii) one or more non-polar active ingredients when the continuous phase is polar;
(b) adding a first silica precursor to the emulsion such that the silica precursor is emulsion templated at a basic pH of between 8-12 onto the surface of the droplets to form a silica-based first shell layer around the droplets, wherein the first silica precursor has the general formula (I):
R 1 x —Si—(OR 2 ) y (I)
wherein R 1 is a substituted or unsubstituted C 12 -C 24 alkyl or a substituted or carboxylate or an alkyl quaternary amine, and R 2 is an alkyl group, x+y=4, and y=1, 2 or 3; and
(c) adding a second silica precursor to the emulsion such that the second silica precursor can be emulsion templated onto the surface of the droplets or deposited on the silica-based first shell layer, wherein the second silica precursor has the general formula (II):
R 3 m —Si—(OR 4 ) n (II)
wherein R 2 is selected from substituted and unsubstituted alkyl, substituted and unsubstituted aryl, alcohols, amines, amides, aldehydes, acids, esters, and functional groups having an unsaturated carbon-carbon bond, R 4 is an alkyl group, m+n=4, and m=0, 1, 2 or 3,
wherein the method produces silica-based particles having a silica-based shell surrounding a liquid core comprising the one or more polar active ingredients or the one or more non-polar active ingredients, wherein the silica-based particles have an overall size of 10 nanometer to 250 microns.
2. The method of claim 1 further comprising;
(d) adding a third silica precursor to the emulsion such that the third silica precursor can be emulsion templated onto the surface of the droplets or droplets or deposited on the silica-based first and/or second shell layers, wherein the third silica precursor has the general formula (III):
R 5 a —Si—(OR 6 ) b (III)
wherein R 5 is selected from substituted and unsubstituted alkyl, substituted and unsubstituted aryl, alcohols, amines, amides, aldehydes, acids, esters, and functional groups having an unsaturated carbon-carbon bond, R 6 is an alkyl group, a+b=4, and a=0, 1, 2 or 3.
3. The method of claim 1 wherein the first silica-based shell layer is a continuously formed shell or a partially formed shell.
4. The method of claim 1 wherein the first shell layer has a first shell layer thickness of from sub-nanometer ranges to 500 nanometers when the first silica precursor and the second silica precursor are templated onto the surface of the droplets, and wherein the first shell layer and the second shell layer together have a thickness in the range of 1 nanometer to 1 micron when the second silica precursor bonds to the first shell layer.
5. The method of claim 1 wherein the R 1 groups are capable of attaching a coating by covalent bonding, noncovalent bonding, ionic bonding, electrostatic attraction, or any other attachment mechanism which allows for coating proximity within sub-nanometer ranges to 500 microns.
6. The method of claim 5 wherein the coating comprises a polymeric material.
7. The method of claim 1 wherein step (a) comprises adding a surfactant selected from cationic, anionic, nonionic and amphoteric surfactants to a first material comprising the continuous phase and a second material comprising the dispersed phase to form the emulsion.
8. The method of claim 7 wherein the surfactant is cationic.
9. The method of claim 7 wherein step (a) comprises adding a second surfactant.
10. The method of claim 7 wherein the R 1 group has a net charge to attract towards an opposite charge of the surfactant at interfaces between the droplets and the continuous phase.
11. The method of claim 1 , wherein the cationic polymer is located in the continuous phase.
12. The method of claim 1 , wherein the cationic polymer is located in the dispersed phase.
13. The method of claim 1 , wherein the basic pH is between 9-11.
14. The method of claim 1 , wherein the first and second silica precursors form templated silica particles has a Zeta potential ranging from −80 mV to 150 mV.
15. The method of claim 1 , wherein the silica-based particles include an oil droplet having a size of 1 nanometer to 200 microns.
16. The method of claim 1 , wherein the ratio of the one or more polar active ingredients or the one or more non-polar active ingredients to the cationic polymer is from 1:1 to 30:1, 1:1 to 20:1, 1:1 to 10:1, or 1:1 to 5:1.
17. The method of claim 1 , wherein the ratio of the first silica precursor to the second silica precursor is from 1:99 to 99:1, 1.50 to 50:1, 1:25 to 25:1, 1:10 to 10:1, 1:5 to 5:1, or 1.2 to 2:1.
18. The method of claim 1 , wherein the ratio of the first silica precursor to the third silica precursor is from 1:99 to 99:1, 1:50 to 50:1, 1:25 to 25:1, 1:10 to 10:1, 1:5 to 5:1, or 1:2 to 2:1.
19. The method of claim 1 , wherein the one or more polar active ingredients or the one or more non-polar active ingredients is a cosmetic product, a detergent product, or oral hygiene product.
20. The method of claim 19 , wherein the cosmetic product is a skin cream or a sunscreen formulation.
21. The method of claim 19 , wherein the detergent product is a laundry wash product, a household cleaner, a shampoo, a hair conditioner or a bleach.
22. The method of claim 19 , wherein the oral hygiene products toothpaste.
23. The method of claim 1 , wherein the one or more polar active ingredients or the one or more non-polar active ingredients is a pharmaceutical or a nutraceutical, or mixtures and combinations thereof.
24. The method of claim 1 , wherein the one or more polar active ingredients or the one or more non-polar active ingredients is a pharmaceutical or a nutraceutical.
25. The method of claim 1 , wherein the one or more polar active ingredients or the one or more non-polar active ingredients is a sunscreen, a steroidal anti-inflammatory active, an analgesic active, an antifungal, an antibacterial, an antiparasitic, an anti-viral, an anti-allergenic, an anti-cellulite additive, a medicinal active, a skin rash medication, a skin disease medication, a dermatitis medication, an insect repellant active, an antioxidant, a hair growth promoter, a hair growth inhibitor, a hair bleaching agent, a deodorant compound, a sunless tanning active, a skin lightening active, an anti-acne active, an anti-skin wrinkling active, an anti-skin aging active, a vitamin, a nonsteroidal anti-inflammatory active, an anesthetic active, an anti-pruritic active, an anti-microbial active, a dental care agent, a personal care agent, a fragrance, an antifouling agent, a pesticide, a lubricant, an etchant, or mixtures and combinations thereof.