0000000000636922
AUTHOR
Amit Halevi
Hierarchical Structuring in Block Copolymer Nanocomposites through Two Phase-Separation Processes Operating on Different Time Scales
Tailoring the size and surface chemistry of nanoparticles allows one to control their position in a block copolymer, but this is usually limited to one-dimensional distribution across domains. Here, the hierarchical assembly of poly(ethylene oxide)-stabilized gold nanoparticles (Au-PEO) into hexagonally packed clusters inside mesostructured ultrathin films of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is described. A close examination of the structural evolution at different nanoparticle filling fractions and PEO ligand molecular weights suggests that the mechanism leading to this structure-within-structure is the existence of two phase separation processes operating on differe…
Co-Assembly of A–B Diblock Copolymers with B′-type Nanoparticles in Thin Films: Effect of Copolymer Composition and Nanoparticle Shape
The coassembly of A–B diblock copolymers with B′-type nanoparticles (i.e., nanoparticles that are slightly incompatible with the B domain) leads to hierarchical structures, where the block copolymer phase separates first and the nanoparticles create close-packed arrays within the B domains due to a slower, secondary phase separation process. Here we report the results of a comprehensive study, which focused on two aspects: the influence of the nanoparticle shape (spherical vs rod-like) and the effect of the volume composition of the blocks. Three polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers featuring similar molecular weights but differing in PS volume fraction were mi…