NOVELTY - A porous particle comprises a water-insoluble polymer that provides a continuous polymeric solid phase including an external particle surface, and at least one discrete cavity having inner walls and that are dispersed within the continuous polymeric solid phase; and further comprises a cavity stabilizing hydrocolloid on the inner walls of the discrete cavities, and amphiphilic (low hydrophilic-lipophilic balance (HLB)) block copolymer that is disposed at the interface of the discrete cavities and the continuous polymeric solid phase.    USE - In drug delivery devices, cosmetic formulations, pharmaceuticals, and as chemical or enzymatic reactors used for biological and organic syntheses or other chemical processes, fuel cells, convertors, or any other application where a catalytically active metallic material is needed for a chemical reaction; in chromatographic columns, ion exchange and adsorption resins, paints, adhesives, and security systems for detection of counterfeits, document authentication, and labeling of consumer goods; in paper and plastic cards e.g. passports and drivers licenses, and other identification cards; into labels, fabrics, tapes, staples, foils, paperboard, and cardboard packaging, varnishes and other coating compositions.    ADVANTAGE - The discrete cavities have inner walls and are dispersed within the continuous polymeric solid phase. The particle can stabilize the water-in-oil emulsions in conjunction with the pore stabilizing hydrocolloids for oil phases that do not have the ideal properties to provide interface stabilization. The porous particles with discrete cavities can be prepared using a water-in-oil-in-water system in a manner that can accommodate a broad spectrum of polymer precursors (ethylenically unsaturated polymerizable monomers) and polymer materials. The random copolymer used in place of the amphiphilic block copolymer, have a much less propensity to effectively assembly and stay at the interface of the first water and oil phases due to its random architecture. The porous particles can be used directly without removing the water from discrete cavities, that is, as aqueous slurries.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparing (M1) a porous particle involving: providing: first aqueous phase comprising a cavity stabilizing hydrocolloid, and oil phase comprising a water-insoluble polymer or polymer precursor, amphiphilic (low HLB) block copolymer and optionally an organic solvent, dispersing the first aqueous phase in the oil phase to form a water-in-oil emulsion, dispersing the water-in-oil emulsion in a second aqueous phase containing a surface stabilizing material to form a water-in-oil-in-water emulsion containing droplets of the water-in-oil emulsion, removing the organic solvent of the oil phase from the water-in-oil-in-water emulsion, or polymerizing a polymer precursor if present, to form a solidified precursor porous particle comprising a water-insoluble polymer that provides a continuous polymeric solid phase including an external particle surface, and the discrete cavities having inner walls and that are dispersed within the continuous polymeric solid phase, where the solidified precursor porous particle further comprises the cavity stabilizing hydrocolloid on the inner walls of the discrete cavities, and the amphiphilic (low HLB) block copolymer that is disposed at the interface of the discrete cavities and the continuous polymeric solid phase, and isolating the solidified precursor porous particle to provide a porous particle.