The defined assembly of functional nanoparticles in polymer matrices is highly desirable for the development of next-generation electrical, optical, memory, and energy conversion devices. Currently, the lack of a precise control of nanoparticle positions, distances, and ordering in polymeric matrices is a severe barrier for many nanotechnology applications. Furthermore, the controlled and stable incorporation of nanoparticles into block polymer matrices remains difficult, because nanoparticles are thermodynamically immiscible with polymers leading to problems of macrophase separation already at small nanoparticle volume fractions. We systematically investigated PbS-, ZnO-, Fe2O3-, and Cu2ZnSnS4-nanoparticles coated with PS-PI block copolymer ligands of different molecular weights. We show that the direct self-assembly of block copolymer coated nanoparticles leads to thermodynamically stable, highly loaded and highly ordered nanocomposites. It enables the incorporation of exactly one nanoparticle per unit domain, and allows precise control of the inter-particle distance at the nanometer scale. We find that the direct coupling of nanoparticle and block copolymer self-assembly leads to new ordered morphologies with locally 2-, 3- and 6-fold rotational symmetry, that have not been reported and are otherwise difficult to access. Our studies demonstrate that the nanoparticle/domain size ratio and the grafting density are the two most important factors that control the type of block copolymer domain structure and the inter-particle distance. The method opens the way to the controlled preparation of well-defined complex nanoparticle arrays in polymer matrices with domain-selective localization such that ordered binary or ternary nanoparticle arrays can be achieved as would be necessary e.g. for scintillation materials.

Controlled assembly of block copolymer coated nanoparticles in 2D-arrays

2019 Fall National Meeting

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