Solvothermal synthesis of hierarchical Eu₂O₃ nanostructures templated by PS-b-PMAA: Morphology control via simple variation of water contents

A new method to synthesize hierarchical Eu₂O₃ nanostructures via a solvothermal process in N,N′-dimethyl formamide (DMF) templated by an ionic amphiphilic diblock copolymer polystyrene-block-poly (methacrylic acid) (PS-b-PMAA) has been developed. By simply varying the mass ratio of H₂O over DMF from 0 to 20 wt% in the polymer-salt mixed solution, a series of Eu₂O₃ morphologies including worm-like nanoparticles, nanoparticulate mesoporous microspheres, staggered sheets, and sheet-built microspheres are synthesized. The mechanism of the morphology control is the combined effect of both, guiding the europium salt in the PMAA domains of the micro-phase separated/self-assembled PS-b-PMAA, and the hydrolysis-condensation process associated with the solvothermal treatment step.