TY - DATA T1 - Single-Molecule Spectroscopic Imaging Studies of Polarity Gradients Prepared by Infusion-Withdrawal Dip-Coating PY - 2014/03/27 AU - Dipak Giri AU - Chelsea N. Hanks AU - Maryanne M. Collinson AU - Daniel A. Higgins UR - https://acs.figshare.com/articles/media/Single_Molecule_Spectroscopic_Imaging_Studies_of_Polarity_Gradients_Prepared_by_Infusion_Withdrawal_Dip_Coating/2311354 DO - 10.1021/jp412508c.s004 L4 - https://ndownloader.figshare.com/files/3948991 KW - TMOS KW - PTMOS KW - IWDC KW - organosilane gradients KW - material polarity KW - SMS data KW - wettability gradient KW - gradient formation KW - polarity gradient KW - micrometer length scales KW - macroscopic length scales KW - recording fluorescence videos KW - Raman maps KW - Sessile drop water contact angle measurements KW - Nonpolar phenyltrimethoxysilane KW - Polarity Gradients KW - phase separation KW - SMS imaging KW - fluorescence spots KW - macroscale polarity gradient KW - Nile Red KW - film polarity KW - Polarity data KW - precursor silanes KW - nonpolar film components N2 - Sol–gel-derived thin films incorporating a one-dimensional polarity gradient are prepared by infusion-withdrawal dip-coating (IWDC) and characterized by single-molecule spectroscopic (SMS) imaging. Nonpolar phenyltrimethoxysilane (PTMOS) and polar tetramethoxysilane (TMOS) are used as precursor silanes during IWDC. Sessile drop water contact angle measurements demonstrate the presence of a wettability gradient in the resulting films, on macroscopic length scales. Raman maps of the phenyl C–H stretch at 3059 cm–1 confirm gradient formation. Material polarity is assessed by SMS imaging, using Nile Red as a polarity-sensitive probe. Polarity data are obtained by recording fluorescence videos of single-molecule emission simultaneously in two spectral bands (590 ± 20 and 640 ± 20 nm). The pairs of fluorescence spots produced by each molecule are identified and analyzed using automated spot-tracking software. The local film polarity is quantified via the Clausius–Mossotti factors calculated from the single-molecule emission data. Histograms prepared from the SMS data confirm the presence of a macroscale polarity gradient. These same data reveal that the gradients are heterogeneous on nanometer to micrometer length scales. In some regions, the data are consistent with phase separation of the polar and nonpolar film components. These studies afford a better understanding of organosilane gradients prepared by sol–gel methods and will aid in the development of new materials for stationary-phase-gradient chemical separations, and for directed transport of liquids, macromolecules, vesicles, and cells. ER -