Reduced Domain Size and Interfacial Width in Fast Ordering Nanofilled Block Copolymer Films by Direct Immersion Annealing

Block copolymers (BCPs) can function as nanoscale templates to organize nanoparticles within selective domains. Most functional applications of nanofilled BCPs generally require a high loading of nanoparticles, which is difficult to achieve due to particle aggregation, slow kinetics of ordering, and disruption of block copolymer order. A key parameter is the periodic domain spacing, L0, which is important for tuning functional properties. We demonstrate direct immersion annealing (DIA) as a promising directed self-assembly (DSA) method to overcome these problems. DIA is shown to fully order highly filled (10.5 vol % Au-PSrPMMA nanoparticles) lamellar poly(styrene-b-methyl methacrylate) (PS–PMMA) BCP films, whose lamellar ordering is practically unimpeded by filler loading. Neutron reflection (NR) further confirms that DIA sharpens the interfacial width between PS–PMMA domains by ∼20%. In situ NR studies further reveal that DIA predominantly induced film ordering in a 5 wt % anisotropic organoclay (C93A) f...