Defect Repair of Polyelectrolyte Bilayers Using SDS: The Action of Micelles Versus Monomers.

Defects within single, double, and triple polyelectrolyte bilayers derived from poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethyammonium chloride) (PDDA) have been repaired using aqueous solutions of sodium dodecyl sulfate (SDS), as evidenced by a reduction in their permeability and an increase in their permeation selectivity. In contrast to the use of monomer solutions of SDS, which were moderately effective in repairing only double and triple bilayers, micellar solutions proved highly effective for all three assemblies. Evidence for intact micelles or micellar fragments being deposited on the surface of single bilayers of PSS/PDDA has been obtained from a combination of atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle measurements.

Clicking the Surface of Poly[1-(trimethylsilyl)propyne] (PTMSP) via a Thiol-Ene Reaction: Unexpected CO/N Permeability.

The surface modification of poly[1-(trimethylsilyl)propyne] (PTMSP) film via a thiol-ene click reaction with sodium 3-mercapto-1-propanesulfonate has yielded membranes having a CO permeance as high as 530 GPU with a CO/N selectivity of 21. This level of performance, together with the simplicity of this surface modification, suggests that such materials could become viable alternatives to some of the most promising membrane materials that are currently being explored for the practical capture of CO from flue gas.

Hyperthin Membranes for Gas Separations via Layer-by-Layer Assembly.

Thin film formation via the Layer-by-Layer method is now a well-established and broadly used method in materials science. We have been keenly interested in exploiting this technique in the area of gas separations. Specifically, we have sought to create hyperthin (<100 nm) polyelectrolyte-based membranes that have practical potential for the separation of CO from N (flue gas) and H from CO (syngas).

Layer-by-layer assembly of a polymer of intrinsic microporosity: targeting the CO/N separation problem.

A polymer of intrinsic microporosity, 1, has been incorporated into a series of polyelectrolyte multilayers via the layer-by-layer deposition method. One of these assemblies [a 6 nm multilayer derived from 1 plus poly(diallyldimethylammonium chloride)] showed exceptional permeation properties with respect to CO2 and N2. Specifically, this film exhibited a CO2 permeance of 130 GPU and a CO2/N2 selectivity of 33.

Radiation-Responsive Esculin-Derived Molecular Gels as Signal Enhancers for Optical Imaging.

Recent interest in detecting visible photons that emanate from interactions of ionizing radiation (IR) with matter has spurred the development of multifunctional materials that amplify the optical signal from radiotracers. Tailored stimuli-responsive systems may be paired with diagnostic radionuclides to improve surgical guidance and aid in detecting therapeutic radionuclides otherwise difficult to image with conventional nuclear medicine approaches. Because light emanating from these interactions is typically low in intensity and blue-weighted (i.