PREPARATION AND PROPERTIES OF COLLOIDAL CORE-SHELL RODS WITH ADJUSTABLE ASPECT RATIOS

Colloidal boehmite (AlOOH) rods were used as cores for the preparation of rods with a silica shell. Via a three-step coating procedure silic a rods with adjustable aspect ratios up to 20 were obtained by varying the amount of the added silica precursor tetraethoxysilane (TES). Sil ica rods are stable in various solvents such as water, ethanol, propan ol, and dimethylformamide (DMF). Moreover, polymer-grafted silica rods can be dispersed in ethanol/toluene mixtures and cyclohexane. Incorpo ration of fluorescein isothiocyanate (FITC) in the silica shell enable s the study of long-time self-diffusion processes in dispersions of ro dlike particles with fluorescence recovery after photobleaching (FRAP) . Fluorescent silica rods also may be used in direct imaging studies w ith confocal scanning laser fluorescence microscopy (CSLM).