This invention is directed to a composition comprising crosslinked expandable polymeric microparticles comprising structured polymers having labile crosslinks or having a labile core and non-labile crosslinks. The starting configuration of the structured polymers constrains the microparticle to an unexpanded volume average particle size diameter of from about 0.05 to about 5,000 microns. Labile crosslinks or the labile core of the structured polymers are subject to degradation which results expansion of the microparticle. The invention is further directed to the use of the composition for modifying the permeability of subterranean formations and increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.