Orientational Control of Polymer Grafted Nanorods

Controllable end-to-end alignment of nanorods in polymer films would enable new applications, especially for metallic nanorods, where coupling of surface plasmon resonances can lead to enhanced electric fields (hot spots) between nanorod ends. To achieve end-to-end alignment, we investigate the dispersion and aggregation behavior of polymer brush-coated nanorods in a chemically identical homopolymer matrix using self-consistent field theory (SCFT). We find good agreement with previous DFT calculations and experiments for side-by-side alignment. However, we also find that thermodynamic aggregation of uniformly grafted nanorods in a polymer matrix will preferentially occur side-by-side rather than end-to-end. To achieve preferential end-to-end linking, we propose using different grafting molecular weights (relative to the length of the matrix chains) on the sides and the ends of the nanorods. We demonstrate this idea with an example system in which the side brush length is chosen so that the side-by-side in...