Nanoparticle-Regulated Phase Behavior and Morphological Development in an Ordered Block Copolymer

Although microphase-ordered block copolymer motifs are employed to template inorganic nanoparticles, only recently has the effect of nanoparticles on copolymer self-assembly been explored. In this work, we examine the influence of nanoparticles on the copolymer order-disorder transition (ODT) temperature. Theoretical results from a hybrid self-consistent field/density functional theory -- supported by experimental observations of a model copolymer/nanoparticle system -- confirm that judicious selection of nanoparticle size and selectivity can be used to increase the ODT temperature at constant concentration. For a given nanoparticle size and selectivity, we show that there likewise exists a critical nanoparticle concentration beyond which the ODT temperature decreases. The ability of nanoparticles to increase the ODT temperature is a unique consequence of their size and is not expected for small-molecule additives. At high concentrations, the nanoparticles form percolated colloidal networks that represent highly confined environments for the copolymer molecules.