Fluorescence lifetime studies of labelled polystyrene latices

Hofstraat, Johannes W.; Verhey, Herman J.; Verhoeven, J. W.; Kumke, Michael U.; Li, G.; Hemmingsen, Sherry L.; McGown, Linda B.

doi:10.1016/s0032-3861(96)01063-4

Cited by 15 publications

(7 citation statements)

References 9 publications

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“…In these systems, an aniline type donor and an arylethylene acceptor are held in a rod-shaped conformation by a piperidine bridge. The extremely solvatochromic CT fluorescence of 1 and related systems has been studied in liquid solution, ,,− in polymeric matrixes, − on solid surfaces, and even in the gas phase under supersonic jet cooled conditions . Because of the very large dipole moment of the CT fluorescent state inferred from various measurements, ,, it has been assumed that the extended geometry of these molecules is maintained after charge separation and does not give way to the “crunch” of the electrostatic attraction that is known to lead to large conformational changes in more flexibly bridged systems …”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Charge-Transfer Fluorescence from Extended and U-shaped Donor−Bridge−Acceptor Systems in Glass-Forming Solvents

et al. 2001

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The behavior is reported of three fluorescent D-bridge-A systems that display a fascinating temperature dependence in glass forming solvents over the temperature range between 77 and 293 K. In two of these systems, a rigid, saturated alkane bridge maintains an extended conformation, and as a result, the chargetransfer (CT) state is of giant dipolar nature. This causes the position of the CT fluorescence to be an extremely sensitive probe for the reorientation polarization of the surrounding medium. As a result, the thermochromism of the continuous CT fluorescence maximum in 2-methyltetrahydrofuran (MTHF) covers the full visible region. In the higher temperature domain (above ca. 145 K), this thermochromism can be quantitatively described via the Lippert-Mataga relation. At lower temperatures, solvent relaxation slows down sufficiently to detect exceptionally large dynamic Stokes shifts of the fluorescence maximum on time scales up to g40 ns. The third D-bridge-A system studied features a U-shaped ground state conformation. Remarkably, this system displays a significant thermochromic shift over a narrow temperature region around 175 K in the nonpolar methylcyclohexane (MCH) in which the other systems display only very minor thermochromism. In this U-shaped system therefore, one monitors the temperature dependence of an internal reorganization instead of a medium relaxation. Extensive ab initio calculations indicate that this internal reorganization must be related to an electrostatically driven conformational collapse of the U-shaped system in the CT state. † Part of the special issue "Noboru Mataga Festschrift".

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Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Charge-Transfer Fluorescence from Extended and U-shaped Donor−Bridge−Acceptor Systems in Glass-Forming Solvents

et al. 2001

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“…This let us consider that there was no a homogeneous encapsulation of dots by polymer particles and that there were dots which were not encapsulated by polymer particles. These results allowed us to emphasize two facts: a) that the dots, which were not encapsulated into polymer particles, underwent degradation during polymerization because they were in direct interaction with the water, and the presence of solved oxygen produces fluorescence quenching by oxidation [13]. And b) dots agglomeration, which favors intimate particle contact causes quenching due to electronic coupling [25].…”

Section: Photoluminescencementioning

confidence: 79%

“…Those methods offer important variations which should be considered before selecting the most suitable. Miniemulsion polymerization displays diverse advantages in contrast with other methods [8,13].…”

Section: Introductionmentioning

confidence: 99%

Effect of synthesis variables on the fluorescence properties of CdSe-polystyrene latexes

et al. 2012

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The development of photoluminescent materials based on the incorporation of quantum dots (QDs) into polymeric latexes has gained importance due to the multiple potential applications. Through the process of miniemulsion polymerization it is possible to encapsulate quantum particles into polymer matrix to provide both chemical stability and to maintain emission properties. The polymerization process was achieved with continuous magnetic stirring and nitrogen atmosphere. Cetyl trimethylammonium bromide (CTAB) was used as surfactant at concentration levels of 1.3×10 -3 , 3.2×10 -3 and 5.4×10 -3 M. The initiator 2,2-azobisisobutyronitrile (AIBN) was used at 0.50 and 0.75 wt % and CdSe QDS were used at 0.075, 0.15 and 0.225 wt%, both in relation to monomer content. A STEM study on the composite latexes and later a statistical study on the measurement of polymer particle diameter let us corroborate that the increment in surfactant concentration produces a decrement in polymer particle size. The obtained composite latexes were stable and showed fluorescence by excitation with UV light. The spectrofluorometry studies indicated that in composite latexes fluorescent emission was a function of polymer particle size, showing higher intensity those formulations with smaller surfactant concentrations and bigger polymer particle size.

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“…This is well known for its sharp sensitivity to the polarity and mobility of the medium. 26,33-37, 38 Compound 1 was covalently attached in the backbone of the co-polymer by co-feeding it in a small quantity together with the monomer mixture. Addition of n-butylamine to 1 provided compound 2, which was used as a low-molecular weight model of co-polymerized 1 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

Raja

Brouwer

Biemans³

et al. 2010

Photochem Photobiol Sci

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In this paper we report the determination of partitioning of coalescing agents (organic co-solvents) in water-borne latex emulsions by means of a fluorescence method. An environment-sensitive fluorescent probe was copolymerized via emulsion polymerization. The presence of organic co-solvents inside the polymer particles is revealed by the photophysical properties of the probe. In particular, the position of the fluorescence emission maximum of co-polymerized can be used to measure the amount of coalescing agent present in the polymer particles. The spectral shifts are shown to be due to the softening of the matrix, rather than to solvation of the probe by the added co-solvent.

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Fluorescence lifetime studies of labelled polystyrene latices

Cited by 15 publications

References 9 publications

Temperature Dependence of Charge-Transfer Fluorescence from Extended and U-shaped Donor−Bridge−Acceptor Systems in Glass-Forming Solvents

Temperature Dependence of Charge-Transfer Fluorescence from Extended and U-shaped Donor−Bridge−Acceptor Systems in Glass-Forming Solvents

Effect of synthesis variables on the fluorescence properties of CdSe-polystyrene latexes

Detection of coalescing agents in water-borne latex emulsions using an environment sensitive fluorescent probe

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