Abstract: A method for the encapsulation and triggered-release of water-soluble or water-dispersible materials. The method comprises a) providing an amount of electrolyte having a charge, b) providing an amount of counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form aggregates, d) adding a compound to be encapsulated, and e) adding nanoparticles to the solution such that nanoparticles arrange themselves around the aggregates. Release of the encapsulated species is triggered by disassembly or deformation of the microcapsules though disruption of the charge interactions. This method is specifically useful for the controlled viscosity reduction of the fracturing fluids commonly utilized in the oil field.

Abstract: A method for the encapsulation and triggered-release of water-soluble or water-dispersible materials. The method comprises a) providing an amount of electrolyte having a charge, b) providing an amount of counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form aggregates, d) adding a compound to be encapsulated, and e) adding nanoparticles to the solution such that nanoparticles arrange themselves around the aggregates. Release of the encapsulated species is triggered by disassembly or deformation of the microcapsules though disruption of the charge interactions. This method is specifically useful for the controlled viscosity reduction of the fracturing fluids commonly utilized in the oil field.

Abstract: A method for making inhomogeneous microparticles comprises a) providing an amount of each of at least two polyelectrolytes having a charge, b) providing an amount of a counterion having a valence of at least 2, c) combining the polyelectrolytes and the counterion in a solution such that the polyelectrolyte self-assembles to form inhomogeneous aggregates, and d) adding nanoparticles to the solution such that nanoparticles arrange themselves around the inhomogeneous aggregates to form inhomogeneous particles. The polyelectrolyte may have a positive or negative charge. The charge ratio R of total charge of the counterions to the total charge of the polyelectrolyte may be greater than 1.0.

Abstract: A method for making hollow nanoparticles, comprises a) providing an amount of a polyelectrolyte having a charge, b) providing an amount of a counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form spherical aggregates, and d) adding nanoparticles to the solution such that nanoparticles arrange themselves around the spherical aggregates. The polyelectrolyte may have a positive or negative charge. The charge ratio R of total charge of the counterions to the total charge of the polyelectrolyte is greater than 1.0.

Abstract: A method for the encapsulation and triggered-release of water-soluble or water-dispersible materials. The method comprises a) providing an amount of electrolyte having a charge, b) providing an amount of counterion having a valence of at least 2, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form aggregates, d) adding a compound to be encapsulated, and e) adding nanoparticles to the solution such that nanoparticles arrange themselves around the aggregates. Release of the encapsulated species is triggered by disassembly or deformation of the microcapsules though disruption of the charge interactions. This method is specifically useful for the controlled viscosity reduction of the fracturing fluids commonly utilized in the oil field.

Abstract: A method for making composite nanoparticles comprises a) providing an amount of a polyelectrolyte having a charge, b) providing an amount of a counterion having a valence of at least 2, the counterion having a charge opposite the charge of the polyelectrolyte, c) combining the polyelectrolyte and the counterion in a solution such that the polyelectrolyte self-assembles to form a plurality of polymer aggregates, the plurality of polymer aggregates having an average diameter less than about 100 nm, d) adding a precursor to the solution, wherein the precursor has a charge opposite the charge of the polyelectrolyte, and e) allowing the precursor to infuse each polymer aggregate and polymerize so as to produce composite nanoparticles. The composite nanoparticles comprise a polymer aggregate containing at least one polyelectrolyte and at least one counterion and a polymer network crosslinked throughout the polymer aggregate. The polymer network may be inorganic, e.g silicon-containing.