A reactive fine particle includes one or more functional compounds A or its precursors having a maximal size of less than 2 microns, adapted for synthesis, modification, curing, cross-linking, secession and/or initiating of polymerization of polymers; and one or more inert particles B having at least the maximal size of 2 microns and carrying said functional compounds A at its outer surface and/or in its inner portion. The compounds A to inert particles B weight ratio is ranging from 0.01A:100B to 50A:100B.