Center for Functional Nanomaterials Seminar

In the first part of this talk, a design of inorganic/organic hybrid nanoparticles is discussed. We synthesized zero-dimensional spherical gold nanoparticles (AuNPs), one-dimensional silver nanowires (AgNWs), and two-dimensional silver nanoplates (AgNPls) to represent the inorganic component. Three-arm star polymer and polyelectrolyte represent the organic component. When we assembled alkyne-functionalized zero-dimensional AuNPs onto carboxyl-functionalized one-dimensional AgNWs by a combination of click-chemistry and estertification with the three-arm (COOH-polyethylene oxide)1-(polystyrene-N3)2 star polymer linker, we observed that the Raman scattering due to aromatic ring in the polystyrene is greatly enhanced. Furthermore, we noticed red-shift and broadening in the respective plasmon resonance peak due to AuNPs and AgNWs. This indicates intra-nanoparticle plasmon resonance coupling. Alternatively, the inorganic/organic hybrid nanoparticles was achieved by electrostatically binding positively charged dimethylaminopyridine-functionalized gold nanoparticles onto negatively charged carboxylated one-dimensional AgNWs and two-dimensional AgNPls. The enhanced electromagnetic field as a result of silver-gold intra-particle interaction allows it to serve as a single-nanoparticle surface enhanced Raman (SER) substrate for chemical sensing.

In the second part of this talk, the surface behavior of carboxylic acid functionalized conjugated bithiophenesilane monodendrons is discussed. The film-forming ability of nth generation bithiophenesilane monodendrons is of interest because they possess bright photoluminescence in solution. This study involved mono- and multi-layer Langmuir-Blodgett assembly of the bithiophenesilane monodendrons. UV-Vis absorption and steady state fluorescence measurements on the bithiophenesilane monodendrons, along with surface topographies were correlated with the molecular packing within the mono- and multi-layer films.