Patent ID: 8632816

Claim:
A method for modifying or treating solid particles, comprising: (a) forming a gelled mixture by mixing either simultaneously or sequentially in any order (1) hollow microspheres each comprising a deformable polymeric shell having entrapped therein an expandable fluid, (2) a first organic solvent which is present in an amount sufficient to swell and implode the microspheres but not dissolve the polymeric shells of the hollow microspheres, and (3) solid particles, wherein molecules of the first solvent enter between polymeric chains of the polymeric shell and disrupt intermolecular bonds between the chains, forming micro-channels in the swelled polymer shells which substantially simultaneously allow entry of the solid particles into the hollow microspheres and exit of a first portion of the expandable fluid therefrom, thereby collapsing the microspheres and entrapping the solid particles therein; (b) introducing a second solvent which is miscible with the first solvent into the gelled mixture with sufficient agitation to quench the gelled mixture, thereby diluting the first solvent and permitting exit of a second portion of expandable fluid from the microspheres so as to form separated microspheres, each comprising a collapsed polymeric shell, having an average particle size in the range of from about 1 to about 50 microns, and having one or more of said solid particles entrapped therein; and (c) removing the expandable fluid and solvents to result in a dry, free-flowing powder.