Luminescence techniques in polymer colloids. 1. Energy-transfer studies in nonaqueous dispersions

Pekcan, Önder; Winnik, Mitchell A.; Egan, Luke S.; Croucher, Melvin D.

doi:10.1021/ma00238a038

Cited by 73 publications

(49 citation statements)

References 3 publications

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“…The densities of the cores can be estimated to be essentially equivalent PMMA polymer with either a small amount of solvent penetration (∼ 0.03) or a slight expansion. Fluorescence energy-transfer studies have shown that small molecules can distribute throughout the cores [103][104][105]. Other small molecules, such as residual hexane solvent [106] or surfactant charging agents [74,76], can also be distributed throughout the cores of the latexes.…”

Section: Discussionmentioning

confidence: 99%

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Smith

Finlayson

Gillespie

et al. 2016

Journal of Colloid and Interface Science

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Section: Discussionmentioning

confidence: 99%

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Smith

Finlayson

Gillespie

et al. 2016

Journal of Colloid and Interface Science

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“…20-40 A by a Forster energy transfer mechanism), we observed that quenching occurred within minutes of sample preparation, even for N groups deep within the core of the particle (8,10). Quite different behavior was concentration is significant, static quenching can contribute to the radiationless decay rate.…”

mentioning

confidence: 83%

“…The synthesis and characterization of the particles have been reported previously (8)(9)(10)(11). The particles, 2 pm in diameter, have compositions containing monomer units in mole ratios of isobutylene/ methyl methacrylate/naphthylmethyl methacrylate of 13: 100:2 and 13: 100: 10.…”

Section: Methodsmentioning

confidence: 99%

Phosphorescence of naphthalene-labelled colloidal polymer particles. The α-methyl relaxation of one microphase in a multicomponent material

Winnik¹,

Pekcan²,

Croucher³

1985

Can. J. Chem.

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Chem. 63, 129 (1985). Nonaqueous dispersions of poly(methy1 methacrylatc) (PMMA) particles, stcrically stabilized with polyisobutylenc (PIS), were prepared with naphthalene (N) groups covalently incorporated into the PMMA chains. These materials have a complcx morphology of phase-separated PMMA and PIS microdomains, with the N groups in the PMMA microphases. The phosphorescence intensity and decay times of the N groups were measured as a function of temperature ovcr the rangc 77-295 K for dispersions in methylcyclohexanc and for freeze-dried powder samples. An Arrhenius treatment of the radiationlcss decay rate showed a changc in slope at -35°C. The activation energy for the radiationlcss decay process is 3.8 kcal/mol in the -35 -+22"C temperature region, identical to that found for pure PMMA by nmr for chain motion associated with the a-methyl relaxation process. We believe that the phosphorcsccnce experiment is sensitive to the diffusion of oxygen and other impurities in the sample. These rates increase as the tempcrature is raised, enhancing the rate of phosphoresccnce quenching. These experiments indicate that phosphorescence measurements on labellcd samples are suitablc for studying relaxation proccsscs within individual microphases of a polyphasic composite material. Phosphorescence measurements on polymer samples doped or labelled with appropriate dye molecules provide powerful means for studying properties of polymers in the solid state. Over the past 20 years various research groups have used these techniques to study the dynamics of gas permeability (I-3), and to detect various relaxation processes (4-7) in polymer films. A careful reading of these papers suggests that both the phosphorescence intensity of a dye and its phosphorescence decay time are sensitive to many of the processes which occur in the glassy state of polymers. One can observe the glass transition (at temperature T,), the p transition (T&, and in some instances the a' transition due to local mode relaxation of the main polymer chain. Examples of sensitivity to sample history including hysteresis effects are known. Activation energies for polymer relaxation pathways can be determined, and these are comparable to those obtained by solid state nmr techniques.o n e of the curious featuresof these experiments is that ' Luminescence of Polymer Colloids 6.'Author to whom correspondence should be dirccted. 'Current address. Department of Physics. Haccttepc University, Ankara, Turkey. nearly all of them have been reported by research groups specializing in luminescence spectroscopy or photochemistry. Either the usefulness of these methods is not appreciated by the polymer community in general or they consider the techniques to be difficult, complex, or arcane. Perhaps it is felt that one needs optically transparent samples and sophisticated equipment. Our results reported here may serve as an incentive to others contemplating such experiments. We report phosphorescence intensity and decay measurements, obtained with rather primitive equipment...

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“…D m was calculated from eq. (23) 3,4 and is an order of magnitude larger than is the averaged desorption coefficient, D (5.4 ϫ 10 Ϫ6 cm 2 /s). This result is expected, because desorption of An together with polymer chains from a swollen gel is always slower than the Brownian motion of An in a liquid environment.…”

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confidence: 89%

Fast transient fluorescence technique (FTRT) for studying dissolution of polymer glasses

Pekcan

Uǧur²

1999

J. Appl. Polym. Sci.

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ABSTRACT:The fast transient fluorescence technique (FTRT) was used for studying the swelling and dissolution of a glassy polymer formed by free-radical polymerization of methyl methacrylate (MMA). Anthracene (An) was introduced during polymerization as a fluorescence probe to monitor swelling and dissolution. Swelling and dissolution processes of disc-shaped poly(methyl methacrylate) (PMMA) glasses in a chloroformheptane mixture were monitored by measuring the fluorescence lifetimes of An from its decay traces. A method is developed for low quenching efficiencies for measuring lifetimes, , of An, and it was observed that values decreased as the dissolution process proceeded. Desorption, D, and mutual diffusion, D m , coefficients of An molecules were measured during dissolution of PMMA and found to be around 5.4 ϫ 10 Ϫ6 (cm 2 /s) and 2.2 ϫ 10 Ϫ5 (cm 2 /s), respectively.

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Luminescence techniques in polymer colloids. 1. Energy-transfer studies in nonaqueous dispersions

Cited by 73 publications

References 3 publications

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Phosphorescence of naphthalene-labelled colloidal polymer particles. The α-methyl relaxation of one microphase in a multicomponent material

Fast transient fluorescence technique (FTRT) for studying dissolution of polymer glasses

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