(162af) A Branched Hybrid: Inducing Fatty Acid Nanorods from Cdse-Mua Nanoparticles

The assembly and integration of nanocrystals is recommended as the ultimate step while considering their applications in the future nano-electronic fabrication. The synthesis of nanocrystals with a higher structure complexity such as branched architecture also became very attractive after the successful synthesis of various nanoparticles, nanorods, and nanowires. In our work, we disclose a novel strategy to achieve a nano-hybrid with a branched structure on graphite surface through seeded nucleation, which is built up by an inorganic nanoparticle and fatty acid nanorods. 11-mercaptoundecanoic acid capped cadmium selenide (MUA-CdSe) nanoparticles are introduced as nucleation centers. An alcoholic mixture of MUA-CdSe and fatty acid is spin coated onto graphite surface. Crystallization of fatty acids is restrained by nanoparticles according to both growing phase and growing direction. Nucleation occurs at the interface between nanoparticles and solution. The high curvature and small size of nanoparticle inhibit the growth on tangential direction and thus the fatty acid nanorods are achieved along the radial direction of MUA-CdSe nanoparticle. In order to get a better understanding on the nucleation, fatty acids with different chain lengths are studied. Nanorods consisting of behenic acid (C22), arachidic acid (C20), and stearic acid (C18) are successfully obtained. Fatty acids usually form B-form fatty acid crystal on graphite surface, which exhibits a nanostripe structure, and AFM images can show their similar structure with different periodicities depending on carbon chain lengths. However, all of the induced nanorods with the same characteristic height belong to C-form crystal and have only one unit cell in their cross-section. This illustrates our strategy to synthesize a nano-hybrid is somehow universal. AFM, TEM and EDS are conducted to characterize the hybrid.