The chromonic liquid-crystalline properties of bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride in an aqueous solution were investigated by polarized light microscopy and 2H NMR spectroscopy. Both techniques indicate a narrow I + N biphasic region and a broad N phase region at concentrations ranging from approximately 6.9 to approximately 30 wt % at room temperature. Optical microscopy indicates that a hexagonal M phase exists at higher concentrations. The variation of the I --> N + I and N + I --> N transition temperatures with concentration was studied by 2H NMR spectroscopy. Finally, the effects of temperature and concentration on the order parameter of the N phase were investigated by 2H NMR using a tetra-deuterated derivative. A value of 0.97 was obtained for the N phase at its upper concentration limit.

Ionic perylenebis(dicarboximide)s 1-5 were synthesized. The aggregation and liquid-crystalline properties of these compounds in aqueous solutions were investigated. In the concentration range of approximately 5 x 10-7-5 x 10-4 M, the structures of the ammonium side chains and counterions did not have a significant effect on the electronic transition properties and H-aggregate formation of these compounds. However, the liquid-crystalline phase properties varied with the structure of the side chains and the counterions. Ionic perylenebis(dicarboximide)s 1, 3, and 5 with chloride ions formed nematic (N) phases from the isotropic (I) phase, while 2 and 4 with p-methylbenzenesulfonate ions formed chromonic ribbons from the I phase. Studies by polarized light microscopy and 2H NMR spectroscopy indicated that the N phase of 5 (with gem dimethyl groups) formed at higher concentrations than those observed for 1 and 3 at the same temperature. Furthermore, the N phase of 5 was less ordered compared to those of 1 and 3 at a similar concentration and temperature, presumably due to the bulkiness of the side chains of 5 that hindered the stacking and pi-interactions of the aromatic rings.

We have developed an approach to generate micropatterns of anisotropic organic materials which exploits the self-organization, driven by pi-stacking and hydrophobic interactions, of an ionic perylenebis(dicarboximide) in aqueous solutions.

Nanoparticle infused personal care products are becoming more common as consumer products. One example is a hair-dryer marketed as emitting silver nanoparticles (Ag NPs). The purpose of the silver nanoparticles (Ag NPs) is to give hair a sleek, shiny look while also promoting antimicrobial effects. This study investigates release of Ag NPs from hair-dryers and the effects associated with Ag NPs to the human epidural flora. To give an estimation of consumer exposure to Ag NPs with these products, three brands of hair-dryers were selected and particle samples from the hair-dryers were collected based on size fractionation. Collected particles underwent elemental analysis. Silver was not detected in any of the samples. The Kirby-Bauer assay was used to detect a toxicity dose response relationship over a range of silver nanoparticles and silver nitrate (AgNO 3) concentrations using four model bacteria species. This portion of work simulated the microbial response to skin exposure with emitted Ag NPs. Findings from this study such as the recorded release of nanoparticles from the hair-dryers and the potential microbial effects to nanoparticle exposure will help consumers make more informed decisions regarding nanoparticle infused products.

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