In this work, a supramol. approach, based on mol. recognition, was used to direct the blending of immiscible polymers toward compatibility and even mol. miscibility.  A slight modification of the two immiscible polymers polystyrene (PS) and poly(Bu methacrylate) (PBMA), with the introduction of the two recognition groups tetraphosphonate cavitand (HOST) and methylpyridinium (GUEST), resp., led to the formation of compatible mixts. between them, characterized by a single Tg and by an homogeneous texture at the surface level, as evidenced by AFM measurements.  The energetically favorable host-guest interactions among polymeric chains overcome their repulsive interfacial energy, leading to the suppression of phase segregation at the level of material.  The complexation between PS-HOST and PBMA-GUEST copolymers has been demonstrated to be reversible by the action of a specific external stimulus in the form of guest exchange with the competitive N-methylbutyl ammonium chloride