Microcapsules adapted to rupture in a magnetic field

Patent metadata

Field	Value
Publication number	US-9307692-B2
Application number	US-201414244921-A
Country	US
Kind code	B2
Filing date	Apr 4, 2014
Priority date	Oct 28, 2011
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Controlled release of one or more agricultural chemicals is provided by microcapsules adapted to rupture in a magnetic field. The microcapsules, which may be applied to soil, seeds and/or plants, each have a shell that encapsulates an agricultural chemical, such as a fertilizer, herbicide or insecticide. One or more organosilane-coated magnetic nanoparticles is/are covalently bound into the shell of each microcapsule. For example, (3-aminopropyl)trimethylsilane-coated magnetite nanoparticles may be incorporated into the shell of a urea-formaldehyde (UF) microcapsule during in situ polymerization. In one embodiment, microcapsules encapsulating a fertilizer are applied during seed planting. Controlled release is subsequently triggered after an appropriate period of dormancy by positioning a magnetic field generating device proximate the microcapsules to generate a magnetic field sufficient to rupture the microcapsule shells through magnetic stimulation of the organosilane-coated magnetic nanoparticles. The ruptured microcapsule shells release the fertilizer.

First claim

What is claimed is:

1. A method of preparing microcapsules adapted to rupture in a magnetic field for controlled release of one or more agricultural chemicals, comprising the steps of:
providing organo trialkoxysilane-coated magnetic nanoparticles;
incorporating one or more of the organo trialkoxysilane-coated magnetic nanoparticles into a shell of each of a plurality of urea-formaldehyde (UF) microcapsules while encapsulating an agricultural chemical into a core of each of the plurality of UF microcapsules, wherein the step of incorporating one or more of the organo trialkoxysilane-coated magnetic nanoparticles into a shell of each of a plurality of UF microcapsules while encapsulating an agricultural chemical into a core of each of the plurality of UF microcapsules includes the step of incorporating one or more organosilane-coated magnetic nanoparticles into the shell of each of the UF microcapsules during in situ polymerization of the UF microcapsules.

2. The method as recited in claim 1 , wherein the step of incorporating one or more of the organo trialkoxysilane-coated magnetic nanoparticles into the shell of each of the plurality of UF microcapsules while encapsulating an agricultural chemical into a core of each of the plurality of UF microcapsules includes the steps of:
preparing an aqueous solution by mixing water, ethylene maleic anhydride (EMA) copolymer, urea, ammonium chloride, resorcinol and the organo trialkoxysilane-coated magnetic nanoparticles;
preparing a core formulation containing the agricultural chemical;
preparing an emulsion by adding the core formulation to the aqueous solution;
adding an aqueous solution of formaldehyde to the emulsion.

3. The method as recited in claim 2 , wherein the agricultural chemical is selected from a group of active ingredients consisting of fertilizers, herbicides, insecticides, and combinations thereof.

4. The method as recited in claim 1 , wherein the step of incorporating one or more of the organo trialkoxysilane-coated magnetic nanoparticles into the shell of each of the plurality of UF microcapsules while encapsulating an agricultural chemical into a core of each of the plurality of UF microcapsules includes the steps of:
preparing an aqueous solution by mixing water, ethylene maleic anhydride (EMA) copolymer, urea, ammonium chloride and resorcinol;
preparing a core formulation containing the agricultural chemical;
preparing an emulsion by adding the core formulation to the aqueous solution;
adding an aqueous solution of formaldehyde and the organo trialkoxysilane-coated magnetic nanoparticles to the emulsion.

5. The method as recited in claim 4 , wherein the agricultural chemical is selected from a group of active ingredients consisting of fertilizers, herbicides, insecticides, and combinations thereof.

6. The method as recited in claim 1 , wherein the step of providing organo trialkoxysilane-coated magnetic nanoparticles includes the steps of:
forming a hydrolyzed silane by reacting an organo trialkoxysilane with a mild acid in an aqueous solution of a solvent;
adding magnetic nanoparticles to the aqueous solution.

7. The method as recited in claim 6 , wherein the mild acid is selected from a group consisting of acetic acid, hydrochloric acid, formic acid, and combinations thereof, and wherein the solvent is selected from a group consisting of tetrahydrofuran, ethanol, methanol, and combinations thereof.

8. The method as recited in claim 7 , wherein the organo trialkoxysilane is aminopropyltriethoxysilane.

9. The method as recited in claim 8 , wherein the magnetic nanoparticles include magnetite nanoparticles.

10. The method as recited in claim 1 , wherein the step of providing organo trialkoxysilane-coated magnetic nanoparticles includes the step of preparing (3-aminopropyl) trimethoxysilane-coated magnetite nanoparticles, and wherein the step of incorporating one or more of the organo trialkoxysilane-coated magnetic nanoparticles into the shell of each of the plurality of UF microcapsules while encapsulating an agricultural chemical into a core of each of the plurality of UF microcapsules includes the step of incorporating one or more of the (3-aminopropyl) trimethoxysilane-coated magnetite nanoparticles into the shell of each of microcapsules during in situ polymerization of the UF microcapsules.

Assignees

• IBM

Inventors

• Boday Dylan J
• Kuczynski Joseph
• Meyer Iii Robert E

Classifications

• A01C21/00 Primary

  Methods of fertilising {, sowing or planting} · CPC title

• A01N25/28 Primary

  Microcapsules {or nanocapsules} · CPC title

• C05G5/35

  Capsules, e.g. core-shell · CPC title

• A01N25/00

  Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application {, e.g. seed treatment or sequential application}; Substances for reducing the noxious effect of the active ingredients to organisms other than pests · CPC title

• C05G5/38

  layered or coated with wax or resins · CPC title