Coherent Random Lasing Realized in Polymer Vesicles

We have demonstrated the realization of a coherent vesicle random lasing (VRL) from the dye doped azobenzene polymer vesicles self-assembled in the tetrahydrofuran-water system, which contains a double-walled structure: a hydrophilic and hydrophobic part. The effect of the dye and azobenzene polymer concentration on the threshold of random laser has been researched. The threshold of random laser decreases with an increase in the concentration of the pyrromethene 597 (PM597) laser and azobenzene polymer. Moreover, the scattering of small size group vesicles is attributed to providing a loop to boost the coherent random laser through the Fourier transform analysis. Due to the vesicles having the similar structure with the cell, the generation of coherent random lasers from vesicles expand random lasers to the biomedicine filed

SANS study of multilayer nanoparticles based on block copolymer micelles

A novel type of three-layer nanoparticles was studied using small-angle neutron scattering (SANS). The particles were prepared by adding methyl methacrylate monomer to a polystyrene-block-poly(methacrylic acid) micellar solution in aqueous buffer and subsequent polymerization by gamma -irradiation. The contrast-matching SANS experiments revealed that upon polymerization, the PMMA chains form a layer on the surface of the PS cores of the original micelles. This is in agreement with the finding that at room temperature, MMA monomer molecules do not penetrate into the micelle core in detectable amounts. In the presented example, the mean core radius of original micelles and the layer thickness were determined to be 99 and 17 Angstrom, respectively. Both characteristics are expected to be controllable by the choice of block copolymer micelles and the parameters of the polymerization process. (C) 2001 Elsevier Science Ltd. All rights reserved

Dependence of structure of polyelectrolyte/micelle complexes upon polyelectrolyte chain-length and micelle size

ABSTRACT: Static light scattering and dynamic light scattering were used to investigate the effect of polyelectrolyte chain length and micelle size on the complex formation between a strong polyelectrolyte, poly(dimethyldiallylammonium chloride) (PDMDAAC), and oppositely charged mixed micelles of Triton X-100 (TX100) and sodium dodecyl sulfate (SDS). Although an increase in the molecular weight of PDMDAAC led to high molar mass of the complex, the degree of binding, defined as the mass ratio of micelle to PDMDAAC in the complex, decreased with increasing PDMDAAC molecular weight. The relation between the molar mass and hydrodynamic size indicated that the complex was compact. With increasing micelle size, the structure of the complex changed from one in which a PDMDAAC molecule binds several micelles to one in which large micelles adsorb one or more low molecular weight PDMDAAC molecule(s). Complexes formed from high molecular weight PDMDAAC fractions and large micelles showed a tendency for coacervation

Micelles of a Diblock Copolymer of Styrene and Ethylene Oxide in Mixtures of 2,6-Lutidine and Water

We studied the micelle formation of a diblock copolymer of styrene and ethylene oxide in mixtures of 2,6- dimethylpyridine (2,6-lutidine) and water. Micelles are formed in a broad solvent composition range with a volume fraction of water ranging from 0.05 to 0.85, where neither polystyrene nor polyethylene oxide homopolymers are soluble. The diffusion behavior of pure solvent mixtures and in solutions of copolymer micelles is reported. In LTD/water mixtures, two diffusive processes corresponding to self-difusion and two modes belonging to mutual diffusion and diffusion of solvent clusters have been found. In copolymer solutions, the mode of copolymer micelle diffusion replaces the mode of solvent cluster diffusion. Quasielastic light scattering, small-angle neutron scattering, and pulsed-field gradient NMR have been employed in our study