Following its resolution by diastereomeric complexation, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI) was used to synthesize a chiral ladder polymer, (+)-PIM-CN. (+)-PIM-COOH was also synthesized by the acid hydrolysis of (+)-PIM-CN. Following characterization, both (+)-PIM-CN and (+)-PIM-COOH were solvent cast directly into semipermeable membranes and evaluated for their ability to enable the selective permeation of a range of racemates, including mandelic acid (Man), Fmoc-phenylalanine, 1,1'-bi-2-naphthol (binol), and TTSBI. High ee values were observed for a number of analytes, and both materials exhibited high permeation rates. A selective diffusion-permeation mechanism was consistent with the results obtained with these materials. Their high permeability, processability, and ease of chemical modification offer considerable potential for liquid-phase membrane separations and related separation applications.
Water-soluble silsesquioxane nanoparticles (NPs) incorporating viologen groups (PXV; 1,1'-bis[3-(trimethoxysilyl)propyl]-4,4'-bipyridinium iodide) have been synthesized by sol-gel polymerization. The electrochromic properties of the bulk film fabricated by layer-by-layer (LbL) assembly have been examined, along with their incorporation into solid-state devices. The orange LbL films show high thermal stability and exhibit a maximum UV-vis absorption at 550 nm. Electrochromic switching of the NPs in liquid electrolyte as well as in the solid state was evaluated by a kinetic study via measurement of the change in transmission (% T) at the maximum contrast. Cyclic voltammograms of the PXV NP LbL films exhibit a reversible reduction at -0.6 V vs Ag/AgCl in a 0.1 M NaClO4(aq) solution, revealing good electrochromic stability, with a color change from orange to dark purple-blue at applied potentials ranging from -0.7 to -1.3 V. Cathodically coloring PXV NP solid-state devices exhibit a switching time of a few seconds between the purple-blue reduced state and the orange oxidized state, showing a contrast of 50% at 550 nm and a coloration efficiency of 205 cm2/C. Their solubility and fairly fast electrochromic switching ( approximately 3 s) at low switching voltages (between 0 and 3.0 V), along with their stability under atmospheric conditions, make PXV NPs good candidates for electrochromic displays.
A method for the synthesis of chemically and thermally robust sulfonic-acid-containing hybrid membrane
materials has been established. These polyelectrolyte membranes are prepared by oxidation of the
corresponding disulfide-bridged polysilsesquioxanes. This strategy allows for high acid-group loading.
Their microstructure is determined by nitrogen adsorption porosimetry, solid-state NMR spectroscopy,
and atomic force microscopy. Application of these hybrid materials as proton-exchange membranes for
fuel cells is investigated by measuring their proton conductivity, which increases linearly with increasing
sulfonic acid content to 6.2 mS/cm.
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