Photochromic Molecular Materials for the Controlled Organization of Nanoparticles

The displacement of polystyrene nanoparticles promoted by bulk azo mass transfer using interferential light illumination will be discussed. For this a variety of different push pull small azo molecules were synthesis and characterized, changing the polarity, hydrophobicity and bulky groups around the azo moiety. These small dyes appear to orientate quicker than similarly report azo polymers, of entanglement of the azobenzene group in the polymeric backbone. These dyes were used to form surface relief grating on the thin films due to the bulk mass transfer. This mass transfer was exploited to align polystyrene nanoparticles in the crests and troughs of the gratings. Secondly, the fabrication of azo nano objects will be discussed, here the photochromic studies showed the azo nanospheres had a larger photochemical conversion then their corresponding thin films. These nanoobjects were then successfully coated with gold nanoparticles by using azo compounds with dithiane or thioacetate ligands that are known to complex gold. The hybrid structure was proved by Raman spectroscopy where surface enhanced resonance effects have been evidenced upon excitation in the gold localized surface plasmon bands. Such assemblies, following a reverse architecture as the azo is situated in the core and not on the periphery, represents the first example of high-payload photochromic nanoparticles