Structure and properties of functionalized bithiophenesilane monodendrons

Structured layer of rhenium dye on SiO₂ and TiO₂ surfaces by Langmuir-Blodgett technique

We demonstrate the Langmuir-Blodgett assembly of two rhenium-bipyridine complexes containing a flexible or an aromatic bridge, and transfer of the monolayer to SiO2 and single crystal TiO2 substrates. Both of the complexes (ReEC and Re2TC) have a hydrophilic carboxylic acid group, which preferentially anchors into the water subphase, and forms stable monolayers at surface pressures up to 40 mN/m. The optimum conditions for the formation of complete monolayers of both ReEC and Re2TC were identified through characterization of the morphology by atomic force microscopy (AFM), the thickness by ellipsometry, and the surface coverage by X-ray photoelectron spectroscopy (XPS). X-ray reflectivity measurements (XRR) are consistent with the orientation of the molecules normal to the substrate, and their extension to close to their calculated maximum length. Parameters derived from XRR analysis show that there is a higher packing density for Re2TC monolayers than for ReEC monolayers, attributable to the more rigid bridge in the Re2TC molecule.

Unimolecular micelles composed of inner coil-like blocks and outer rod-like blocks crafted by combination of living polymerization with click chemistry

Star-shaped PS-b-P3HT was synthesized via a combination of ATRP, GRIM polymerization, and click reaction. They possessed different properties as compared to their linear analogues

pH-controlled assembly and properties of LbL membranes from branched conjugated poly(alkoxythiophene sulfonate) and various polycations

We report on multilayer layer-by-layer (LbL) films of the conjugated polymer sodium poly[2-(3-thienyl)ethyloxy-4-butylsulfonate] (PTH) assembled with polycations: poly(diallyldimethylammonium chloride) (PDDA), 20% quaternized poly(N-ethyl-4-vinylpyridinium bromide) (Q20), poly(ethylene imine) (PEI), and poly(allylamine hydrochloride) (PAH). These films were prepared through spin-assisted LbL assembly under various pH conditions. We demonstrated a crucial role of the deposition pH in formation of PTH/polycation films and showed that decrease in the deposition pH from 7.5 to 2.5 limits the PTH multilayer formation to Q20/PTH and PDDA/PTH films due to reduced charge density in the poly(thiophene) chains. We show that optical and surface properties of the resulting PTH/polycation films can be tuned by varying a polycation component and/or by varying the deposition pH. The fluorescence properties of the Q20/PTH, PEI/PTH, and PDDA/PTH films are pH-dependent, and the films exhibit the drastic changes in photoluminescent intensity when transferred into solutions with different pH values, which may find useful in optical sensing applications.