Abstract: In some embodiments, the present invention provides novel methods of preparing porous silicon films and particles for lithium ion batteries. In some embodiments, such methods generally include: (1) etching a silicon material by exposure of the silicon material to a constant current density in a solution to produce a porous silicon film over a substrate; and (2) separating the porous silicon film from the substrate by gradually increasing the electric current density in sequential increments. In some embodiments, the methods of the present invention may also include a step of associating the porous silicon film with a binding material. In some embodiments, the methods of the present invention may also include a step of splitting the porous silicon film to form porous silicon particles. Additional embodiments of the present invention pertain to anode materials derived from the porous silicon films and porous silicon particles.

Abstract: Methods of fabricating porous silicon by electrochemical etching and subsequent coating with a passivating agent process are provided. The coated porous silicon can be used to make anodes and batteries. It is capable of alloying with large amounts of lithium ions, has a capacity of at least 1000 mAh/g and retains this ability through at least 60 charge/discharge cycles. A particular pSi formulation provides very high capacity (3000 mAh/g) for at least 60 cycles, which is 80% of theoretical value of silicon. The Coulombic efficiency after the third cycle is between 95-99%. The very best capacity exceeds 3400 mAh/g and the very best cycle life exceeds 240 cycles, and the capacity and cycle life can be varied as needed for the application.

Abstract: An improved process for converting an oil suspension of nanoparticles (NPs) into a water suspension of NPs, wherein water and surfactant plus salt is used instead of merely water and surfactant, leading to greatly improved NP aqueous suspensions.

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: New methods for the synthesis of nanocrystals/quantum dots are disclosed. The methods comprise use of reasonably-priced and commercially available heat transfer fluids (such as Dowtherm® A) as solvents to synthesize CdSe nanocrystals. Separation of nucleation and growth is achieved by quenching the reaction solution with relatively cold (room temperature) solvent to lower the solution temperature. Quenching may be followed by raising the solution temperature, to allow controlled growth to take place.

Abstract: Methods of nanoencapsulation are described herein. Embodiments of the method utilize the coacervation of a cationic polyelectrolyte with an anionic polyelectrolyte to form a novel capsular matrix. In particular, the novel methods may be used to encapsulate a suspension of a hydrophobic material such as a carotenoid. The disclosed methods do not require lengthy pH adjustments nor do they require the use of any toxic crosslinking agents. In one embodiment, a method of encapsulation comprises dispersing a hydrophobic compound in an organic solvent to form a solution. The method also comprises admixing an anionic polyelectrolyte and a cationic polyelectrolyte with the suspension to form a mixture. In addition, the method comprises quiescently cooling the mixture so as to cause self-crosslinking of a capsular matrix encapsulating the hydrophobic particles.

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 process for making a porous catalyst, comprises a) providing an aqueous solution containing a nanoparticle precursor, b) forming a composition containing nanoparticles, c) adding a first catalytic component or precursor thereof and a pore-forming agent to the composition containing nanoparticles and allowing the first catalytic component, the pore-forming agent, and the nanoparticles form an organic-inorganic structure, d) removing water from the organic-inorganic structure; and e) removing the pore-forming agent from the organic-inorganic structure so as to yield a porous catalyst.

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.

Abstract: Self-healing copolymeric materials comprising a plurality of intermediate strength crosslinks are provided. The copolymeric materials comprise a silicon component and a plurality of crosslinking components. The crosslinking components comprise a polymeric structure forming a structure held together by ionic and/or hydrogen bonding with a net intermediate strength. The plurality of intermediate strength crosslinks provide toughness to the material, and allow for rehealing by allowing reforming of the crosslinks after a disruptive stress incidence. The material is also suited for recasting, and can be used as an active matrix by incorporating additional substances. Articles of manufacture incorporating such materials, and methods of recasting such materials are also provided.

Abstract: Self-healing copolymeric materials comprising a plurality of intermediate strength crosslinks are provided. The copolymeric materials comprise a silicon component and a plurality of crosslinking components. The crosslinking components comprise a polymeric structure forming a structure held together by ionic and/or hydrogen bonding with a net intermediate strength. The plurality of intermediate strength crosslinks provide toughness to the material, and allow for rehealing by allowing reforming of the crosslinks after a disruptive stress incidence. The material is also suited for recasting, and can be used as an active matrix by incorporating additional substances. Articles of manufacture incorporating such materials, and methods of recasting such materials are also provided.