Synthesis and Photophysical Properties of Some PEG Substitued Titanyl Phthalocyanine Derivatives

Summary: Polyethylene glycol substituted titanyl phthalocyanine was prepared in two steps starting from phthalonitrile and characterized by FT-IR, UV-vis spectrophotometry, and fluorescence spectrophotometry. The titanyl phthocyanine derivatives (TiOPcs) showed high solubility in common organic solvents, such as, CH₃Cl and DMF. These compounds decreased in absorbance intensity with increase of molecular weight of polyethylene glycol at maxima wavelength of visible range. The fluorescence spectra showed a fluorescence emission near 690 nm with a quantum yield of 0.05–0.32 (λ_ex = 625 nm).     

Fluorescence sensing of ammonium and organoammonium ions with tripodal oxazoline receptors

A new class of fluorescence sensors for ammonium and organoammonium ions has been disclosed. One of the sensors, an alaninol-derived tripodal oxazoline (1a) shows significant fluorescence enhancement upon binding NH(4)(+) but little response toward K(+), Na(+), and Mg(2+) ions. Owing to its chiral environment, a phenylglycinol-derived tripodal oxazoline (1b) shows chiral discrimination in fluorescence upon binding enantiomeric guests. [reaction: see text]     

Biodegradable aliphatic polyester ionomers

A series of polyester-based ionomers containing dimethyl 5-sulfoisophthalate sodium salt (DMSI) with up to 5 mol-% diacid units was synthesized by two-step polycondensation. Furthermore a polylactic acid (PLA) was modified by introducing poly(ethylene-co-methacrylic acid) ionomers with different ion groups, such as Na, Li, and Zn, using the melt blending method. This review examines the effect of the ionic group on the dynamic mechanical properties, melt rheology, crystallization behavior, degradation behavior, and biocompatibility with human dermal cells, as well as the nucleating effect of poly(ethylene-co-methacrylic acid) ionomer in PLA.     

Synthesis of polystyrene brush on multiwalled carbon nanotubes treated with KMnO4 in the presence of a phase‐transfer catalyst

Multiwalled carbon nanotubes (MWNTs) were effectively functionalized with KMnO₄ in the presence of a phase‐transfer catalyst at room temperature. The hydroxyl functionalized MWNTs were reacted with a vinyl‐group carrying silane‐coupling agent and the terminal vinyl groups were used to fabricate polystyrene (PS) brushes by solution polymerization. Finally, PS‐encapsulated MWNTs were obtained. The synthesis results were verified from FT‐Raman, thermal gravimetric analysis, energy dispersive X‐ray analysis, and transmission electron microscope. PS‐encapsulated MWNTs had much improved dispersion stability in hydrophobic medium, toluene since grafted hydrophobic PS interacts with media and has improved compatibility. This functionalization technique would provide a facile route to prepare various polymer brushes on the surface of MWNTs to improve the dispersion of MWNTs for potential applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4413–4420, 2007     

Effect of pressure and temperature on chromophore reorientation in a new syndioregic main‐chain hydrazone nonlinear optical polymer

Second harmonic generation (SHG) was used to measure the temperature dependence of the reorientation activation volume (ΔV*) of a syndioregic main‐chain hydrazone (SMCH) nonlinear optical polymer. The decay of the SHG signal from poled films of SMCH was recorded at hydrostatic pressures up to 2924 atm and at temperatures between 25 °C below the glass‐transition temperature (T_g) to 20 °C above it. ΔV* for pressures less than 500–1000 atm and T > T_g decreased as the temperature was increased. For pressures greater than 1000 atm, ΔV* was essentially constant for all temperatures. In addition, the size of ΔV* indicated that the chromophore in this main chain was internally flexible. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 895–900, 2001     

Evaluation of inhibitory effect of coptisine on protein kinase C activity using a RI detection-assisted biochip

Journal of Radioanalytical and Nuclear Chemistry - In this study, a radioisotope (RI) detection-assisted biochip was developed for the evaluation of the inhibitory effects of natural products on...     

Preparation and electrorheological characteristic of CdS/Polystyrene composite particles

Cadmium sulfide/polystyrene (CdS/PS) hybrid particles were synthesized and their physical characteristics including electrorheology were examined. Monodisperse CdS/PS nanocomposite particles with diameters of 2 μm were obtained via dispersion polymerization. To form cadmium sulfide nanoparticles onto the PS surface, 2-(dimethylamino)ethyl methacrylate was used as a functional monomer for coordinating with Cd²⁺ ions. Finally, cadmium sulfide nanoparticles with size < 10 nm were formed with the release of S²⁻ ions from thioacetamide. The morphology of the as-prepared CdS/PS nanocomposite particles clearly showed that the CdS particles are present on the surface of the PS. The optical properties were also studied. In addition, their electrorheological characteristics were confirmed by using optical microscopy with applied electrical field. Recently, dielectric properties of CdS nanoparticles were already reported; however, electrorheological characteristics of CdS/PS nanocomposite particles were investigated for the first time.     

Improvement of thermal conductivity of poly(dimethyl siloxane) using silica-coated multi-walled carbon nanotube

In order to enhance the thermal conductivity of MWCNT filled poly(dimethyl siloxane) (PDMS) composites, the MWCNT was coated with silica layer by three step reactions. The composites filled with raw and silica-coated MWCNTs were prepared and the properties were investigated in terms of the curing characteristics, mechanical properties, and thermal conductivity. Due to the poor compatibility between raw MWCNT and PDMS, raw MWCNT showed poor dispersion uniformity and wettability in PDMS. On the other hand, due to the chemical affinity between silica/MWCNT and PDMS throughout the hydrogen bonding, the silica-coated MWCNT filled PDMS showed improved mechanical properties in terms of tensile strength and 100% modulus, and good interfacial compatibility than raw MWCNT incorporated PDMS. Finally, the good wettability of silica/MWCNT in PDMS resulted in higher thermal conductivity caused from the facile phonon movement at the interface even with the smaller MWCNT contents.