Two different methods of surface modification of cotton fabrics are compared: direct fluorination using elemental fluorine and admicellar polymerization, which uses a surfactant and fluoromonomer system. Sample characterization includes infrared spectroscopy, analysis of mechanical properties, analysis of wetting times, contact angle measurements, scanning electron microscopy, elemental analysis, and atomic force microscopy analysis. Fourier transform infrared spectroscopy and elemental analysis showed the presence of fluorine moieties. For direct fluorinated cotton fabric, the static contact angle was found to be 117°, and for cotton fabric modified by admicellar polymerization, the contact angle was 125°. In all cases, the presence of a very thin fluorocarbon layer on the surface was confirmed, but differences in terms of the amount of fluorochemical formed and in surface structure were also found.

Here we report an unconventional colloidal lithography approach for fabricating a variety of periodic polymer nanostructures with tunable geometries and hydrophobic properties. Wafer-sized, double-layer, non-close-packed silica colloidal crystal embedded in a polymer matrix is first assembled by a scalable spin-coating technology. The unusual non-close-packed crystal structure combined with a thin polymer film separating the top and the bottom colloidal layers render great versatility in templating periodic nanostructures, including arrays of nanovoids, nanorings, and hierarchical nanovoids. These different geometries result in varied fractions of entrapped air in between the templated nanostructures, which in turn lead to different apparent water contact angles. Superhydrophobic surfaces with >150° water contact angles and <5° contact angle hysteresis are achieved on fluorosilane-modified polymer hierarchical nanovoid arrays with large fractions of entrapped air. The experimental contact angle measurements are complemented with theoretical predictions using the Cassie's model to gain insights into the fundamental microstructure-dewetting property relationships. The experimental and theoretical contact angles follow the same trends as determined by the unique hierarchical structures of the templated periodic arrays.

Based on MR imaging the development and fusion of the acromion and distal clavicle in children occur earlier than previously reported. They follow a sequential pattern and can serve as a blueprint for evaluating imaging studies of pediatric shoulders.