Aspect-Ratio Effect of Nanorod Compatibilizers in Conducting Polymer Blends

Nanoparticles (NPs) at the interface between two different polymer blends or fluid mixtures can function as compatibilizers, thereby dramatically improving the interfacial properties of the blends or the fluid mixtures. Their compatibilizing ability is strongly dependent on their size, shape, and aspect ratios (ARs), which determines their adsorption energy to the interface as well as their entropic penalty when they are being strongly segregated at the interface. Herein, we investigated the effect of the ARs of nanorod surfactants on the conducting polymer blend of poly(triphenylamine) (PTPA) templated by polystyrene (PS) colloids. The lengths of the polymer-coated CuPt nanorods (CuPt NRs) were 5, 15, and 32 nm with a fixed width of 5 nm, thus producing three different AR values of 1, 3, and 6, respectively. For quantitative analysis, the morphological and electrical behaviors of the polymer blends were investigated in terms of the volume fraction and AR of the NRs. The dramatic change in the morphological and electrical properties of the blend film was observed for all three NR surfactants at the NR volume fraction of approximately 1 vol %. Therefore, NR surfactants with larger ARs had better compatibilizing power for a given number of NRs in the blends. Also, they exhibited a stronger tendency to be aligned parallel to the PS/PTPA interface. Also, we demonstrated the successful use of the NR surfactants in the fabrication of conducting polymer blend film that requires only minimal concentrations of conducting polymers. To the best of our knowledge, this is the first report of an experiment on the AR effect of NR compatibilizers in polymer blends.