Reaction-induced ordering phenomena in binary polymer mixtures

Mesoscopic ordering processes have been found in binary polymer mixtures where only one polymer component was selectively cross-linked by irradiation with ultraviolet light. Depending upon the competitions between the reaction and the phase separation, the mixture can be destabilized and exhibits a wide range oi mesoscopic structures such as spatially modulated. concentric (target) and/or labyrinthine patterns in the micrometer range. Our results suggest the existence of a pattern selection process driven by photochemical reactions in polymeric materials.