02793nas a2200229   4500008004100000022001400041245017300055210006900228260007100297300001600368490000600384520184200390653003002232653001802262653002902280653003102309653002102340653002902361100002602390700001702416856013002433       2013                        eng d  a1944-824400aFluorescent cross-linked polystyrene perylenebisimide/oligo(p-phenylenevinylene) microbeads with controlled particle size, tunable colors, and high solid state emission0 aFluorescent crosslinked polystyrene perylenebisimideoligopphenyl  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV  a12205-122140 v53 a<p>A series fo cross-linked fluorescent polystyrene (PS) microbeads with narrow size distribution and intense solid state emission was developed. Fluorophores based on perylene bisimide (PBI) and oligo(p-phenylenevinylene) (OPV) designed as acrylic cross-linkers were introduced into the polymerization recipe in a twostage dispersion polymerization, carried out in ethanol in the presence of poly(vinylpyrrolidone) (PVP) as stabilizer. The structural design permitted introduction of up to 10(-5) moles of the fluorophores into the polymerization medium without fouling of the dispersion. The particle size measured using dynamic light scattering (DLS) indicated that they were nearly monodisperse with size in the range 2-3 mu m depending on the amount of fluorophore incorporated. Fluorescence microscope images of ethanol dispersion of the sample exhibited intense orange red emission for PS-PBI-X series and green emission for PS-OPV-X series. A PS incorporated with both OPVX and PBIX exhibited dual emission upon exciting at the OPV wavelength of 350 nm and PBI wavelength of 490 nm, respectively. The low incorporation of fluorophore resulted in almost complete absence of aggregation induced reduction in fluorescence as well as red-shifted aggregate emission. The solid state emission quantum yield measured using integrating-sphere setup indicated a very high quantum yield of phi(powder) = 0.71 for PSOPV-X and phi(powder) = 0.25 for PS-PBI-X series. The cross-linked PS microbeads incorporating both OPV and PBI chromophores had a phi(powder) = 0.33 for PBI emission and phi(powder) = 0.20 for OPV emission. This strategy of introducing fluorophore as crosslinkers into the PS backbone is very versatile and amenable to simultaneous addition of different suitably designed fluorophores emitting at different wavelengths.</p>10adispersion polymerization10adual emission10afluorescent cross-linker10aoligo(p-phenylenevinylene)10aPerylenebisimide10asolid state fluorescence1 aSonawane, Swapnil, L.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/fluorescent-cross-linked-polystyrene-perylenebisimideoligop-phenylenevinylene-microbeads-001704nas a2200157   4500008004100000022001400041245012100055210006900176260007100245300001400316490000800330520103800338100002601376700001701402856012701419       2014                        eng d  a1520-610600aBlue, green, and orange-red emission from Polystyrene microbeads for solid-state white-light and multicolor emission0 aBlue green and orangered emission from Polystyrene microbeads fo  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAUG  a9467-94750 v1183 a<p>Solid-state white-light emission was achieved from polystyrene (PS) microbeads incorporated with fluorophores based on perylene bisimide (PBITEG) and oligo(p-phenylenevinylene) (OPV) as acrylic cross-linkers. The PS beads incorporated with only PBITEG gave intense orange-red emission; PS incorporated with OPV exhibited blue-emission, whereas a series of polymers incorporating both cross-linkers exhibited varying shades of white-light emission. One of the PS samples, PS-PBITEG-6.25-OPV-4.28 (PBITEG incorporation: 6.25 X 10(-7) mole; OPV incorporation: 4.28 x 10(-7) mol), exhibited pure white-light emission in the powder form with CIE coordinates (0.33, 0.32). The rigid aromatic cross-linkers were incorporated into the PS backbone in a two-stage dispersion polymerization to afford PS beads in the size range 2 to 3 mu m. The incorporation of fluorophores as cross-linkers enabled covalent attachment of the dye to the polymer backbone, avoiding dye leakage besides avoiding aggregation-induced fluorescence quenching.</p>1 aSonawane, Swapnil, L.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/blue-green-and-orange-red-emission-polystyrene-microbeads-solid-state-white-light-and-002535nas a2200217   4500008004100000022001400041245010900055210006900164260007100233300001600304490000600320520170900326653003002035653002702065653002102092653001102113653002602124100002602150700001702176856012402193       2016                        eng d  a1944-824400aFluorescent polystyrene microbeads as invisible security ink and optical vapor sensor for 4-nitrotoluene0 aFluorescent polystyrene microbeads as invisible security ink and  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR  a10590-105990 v83 a<p>Color-tunable solid-state emitting polystyrene (PS) microbeads were developed by dispersion polymerization, which showed excellent fluorescent security ink characteristics along with sensitive detection of vapors of nitro aromatics like 4 nitro toluene (4-NT). The fluorophores pyrene and perylenebisimide were incorporated into the PS backbone as acrylate monomer and acrylate cross-linker, respectively. Solid state quantum yields of 94 and 20% were observed for the pyrene and perylenebisimide, respectively, in the PS/Py and PS/PBI polymers. The morphology and solid state fluorescence was measured by SEM, fluorescence microscopy, and absorbance and fluorescence spectroscopy techniques. The ethanol dispersion of the polymer could be used directly as a fluorescent security ``invisible'' ink, which became visible only under ultraviolet light. The color of the ink could be tuned depending on the amounts of the pyrene and perylenebisimide incorporated with blue and orange-green for pyrene alone or perylenebisimide alone beads respectively and various shades in between including pure white for beads incorporating both the fluorophores. More than 80% quenching of pyrene emission was observed upon exposure of the polymer in the form of powder or as spin-coated films to the vapors of 4-NT while the emission of perylenebisimide was unaffected. The limit of detection was estimated at 10(-5) moles (2.7 ppm) of 4-NT vapors. The ease of synthesis of the material along with its invisible ink characteristics and nitro aromatic vapor detection opens up new opportunities for exploring the application of these PS-based materials as optical sensors and fluorescent ink for security purposes.</p>10adispersion polymerization10ainvisible security ink10aPerylenebisimide10apyrene10asolid state detection1 aSonawane, Swapnil, L.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/fluorescent-polystyrene-microbeads-invisible-security-ink-and-optical-vapor-sensor-401904nas a2200145   4500008004100000245012900041210006900170260000800239300001400247490000700261520132400268100002601592700001701618856012301635       2017                        eng d00aProbing cavity versus surface preference of fluorescent template molecules in molecularly imprinted polystyrene microspheres0 aProbing cavity versus surface preference of fluorescent template  cMAY  a1558-15650 v553 aFunctional polystyrene (PS) crosslinked microbeads were developed by dispersion polymerization as fluorescent molecularly imprinted polymers (MIPs) having cavities with specific recognition sites. The functional azobenzene molecule modified with pyridine was self-assembled with Pyrenebutyric acid (template molecules), and introduced during the second stage of dispersion polymerization of polystyrene. The template molecule was removed from MIP by Soxhlet using acetonitrile as solvent. Non imprinted polymer (NIP) having no template was also synthesized for comparative study. Fluorescence spectroscopy could be used as a tool to derive insight into the location of the template molecules on the MIP or NIP. The template molecules were adsorbed on the surface of the NIPs during binding studies, which was evidenced from the pyrene excimeric emission observed at 440 nm. The template binding efficiency of the NIPs were much lower compared to MIPs. Pyrene emission from MIP upon rebinding showed typical monomeric emission in the 375-395 nm range, confirming its location in isolated cavities. In rebinding studies of the template molecules, the MIPs selectively took up the template for which the cavity was designed, which demonstrated their selectivity towards template molecules. (C) 2017 Wiley Periodicals, Inc.1 aSonawane, Swapnil, L.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/probing-cavity-versus-surface-preference-fluorescent-template-molecules-molecularly