Fabrication of Nanoparticle/Nanorod Hybrid Structure Using Nanoparticles as Nucleation Seeds

Inorganic nanoparticles with various size and surface functionality are used as nucleation seeds for the crystallization of nano-sized organic crystals. This presentation describes the synthesis, characterization, and immobilization of gold nanoparticles (AuNPs) as well as their capability as nucleation seeds. AuNPs capped with 11-mercaptoundecanoic acid (MUA) and oleylamine (OA) were synthesized by one phase reaction. The NPs were characterized by AFM, TEM, XRD, FTIR, and TGA. MUA-AuNPs and OA-AuNPs were used to induce nanorod formation of carboxylic acids including eicosanoic acid (C20A). The presence of the nanoparticles strongly perturbs the self-assembled patterns of carboxylic acids on graphite. We hypothesize that the curvature of nanoparticles prevents tangential crystallization and results in narrow rod-shaped crystals. The MUA-AuNPs with an average size of 5 nm were effective in inducing C20A nanorods. The OA-AuNPs have a higher degree of size variation, 3-30 nm. The smaller OA-AuNPs, 3-15 nm in size, favored the nanorod formation while OA-AuNPs larger than 15 nm were ineffective nucleation agents. The carboxylic chain length effect was also investigated. We demonstrate that the nanoparticle-induced nanorod formation can be widely applies beyond the initial MUA-capped nanoparticle/C20A combination. AuNPs are the most studied nanoparticles. MUA-AuNPs exhibit higher stability than their cadmium selenide counterparts. Nanoparticle-induced nanorod formation promises a new approach for making organic-based nanorods, nanorod patterns, and interconnects for nanoparticle array devices.