a method for making biocompatible polymeric matrices , particularly polymeric particles , that have functional groups on the surface thereof are provided . the method comprises : providing a biocompatible base polymer ; providing a surface - active , functional polymer , hereinafter referred to as an “ safp ”; entangling chains of the base polymer with chains of the safp , both of which are in a mobile state ; and then demobilizing the base polymer chains to form a polymeric particle or matrix having a specific geometry . polymeric particles having functional groups on the surface thereof are also provided . the particles comprise a biocompatible base polymer and an safp . the safp comprises one or more interactive regions for physically cross - linking with the base polymer , and one or more hydrophilic regions . the particles have a core region and an outer region having a an outer surface . the core region contains a plurality of biocompatible base polymer chains . the outer region of the particle contains a plurality of biocompatible base polymer chains and the interactive regions of the safp . the hydrophilic functional region or regions of the safp chains extend from the surface of the particle when the particle is placed in an aqueous solution .