Search Results - (Author, Cooperation:M. A. Winnik)
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1Latest Papers from Table of Contents or Articles in PressP. A. Rupar ; L. Chabanne ; M. A. Winnik ; I. Manners
American Association for the Advancement of Science (AAAS)
Published 2012Staff ViewPublication Date: 2012-08-04Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: *Micelles ; Microscopy, Electron, Transmission ; Nanoparticles/*chemistry/ultrastructure ; Nanotechnology/*methods ; Polymers/*chemistryPublished by: -
2Latest Papers from Table of Contents or Articles in PressH. Qiu ; Z. M. Hudson ; M. A. Winnik ; I. Manners
American Association for the Advancement of Science (AAAS)
Published 2015Staff ViewPublication Date: 2015-03-21Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsPublished by: -
3Latest Papers from Table of Contents or Articles in PressH. Qiu ; Y. Gao ; C. E. Boott ; O. E. Gould ; R. L. Harniman ; M. J. Miles ; S. E. Webb ; M. A. Winnik ; I. Manners
American Association for the Advancement of Science (AAAS)
Published 2016Staff ViewPublication Date: 2016-05-07Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsPublished by: -
4Articles: DFG German National LicensesStaff View
ISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: A theoretical model for excitation trapping in poly-(N-vinylcarbazole) in the presence of excimer dissociation is presented. We assume a time-dependent trapping coefficient in the form k(t)=b+ct−1/2, which reflects both the diagonal disorder and quasi-one-dimensionality of carbazole hopping sites [Kauffmann et al., J. Chem. Phys. 85, 3566 (1986)]. The equations obtained for monomer and excimer fluorescence decays are given in terms of Laplace transforms. Respective equations for fluorescence decays have been obtained also in the case when excimer formation is time dependent. Equations for monomer and excimer quantum yields are also given.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesStaff View
ISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: A theoretical model for diffusion-controlled excimer formation in the presence of excimer dissociation is presented. We assume that the rate coefficient for excimer formation k1(t) has the form k1(t)=a+bt−1/2. The equations obtained for monomer and excimer fluorescence decays are given in terms of Laplace transforms. Numerical analysis of monomer and excimer fluorescence decays are given in order to show the influence of dissociation, diffusion, and solution concentration on fluorescence decays. It has been shown that dissociation leads to exponentialization of decay curves. Two different methods of calculation quantum yields of monomer and excimer fluorescence are given in the case of time-dependent excimer formation and dissociation.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1435-1536Keywords: Polymerblends ; fluorescence decay ; polymer colloids ; energy migrationSource: Springer Online Journal Archives 1860-2000Topics: Chemistry and PharmacologyMechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision MechanicsNotes: Abstract Fluorescence polarization measurements have been carried out in hydrocarbon solvents on non-aqueous colloidal polymer dispersions labelled with anthracene [A] groups. The polymer particles are composed (dry volume) of 9% polyisobutylene and 91% poly(methyl methacrylate) [PMMA]. The A groups were introduced during particle synthesis using 9-anthrylmethyl methacrylate as a comonomer with MMA. The extent of polarization decreases with increasing A content of the PMMA phase and increasing temperature increases the steady state fluorescence polarization. These results can be explained in terms of immobile A groups which are sufficiently close that some energy transfer [A*+A→A+A*] contributes to fluorescence depolarization.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesBuback, M. ; Gilbert, R. G. ; Russell, G. T. ; Hill, D. J. T. ; Moad, G. ; O'Driscoll, K. F. ; Shen, J. ; Winnik, M. A.
Bognor Regis [u.a.] : Wiley-Blackwell
Published 1992Staff ViewISSN: 0887-624XKeywords: polymerization ; kinetics ; free radical ; transfer ; photolysis ; propagation ; rate coefficients ; termination ; EPR ; copolymerization ; initiation ; Chemistry ; Polymer and Materials ScienceSource: Wiley InterScience Backfile Collection 1832-2000Topics: Chemistry and PharmacologyNotes: The problems of determining reliable, well-characterized values of kinetic parameters in free-radical polymerizations are discussed. The origins of the fact that experimental determinations of rate coefficients of ostensibly identical systems often result in quite different values being reported can be ascribed to subtle mechanistic assumptions made in data interpretation, which are considered in detail. A series of recommendations to assist in overcoming these problems, and to highlight their origins, are presented, with emphasis placed on new techniques including those employing laser photolysis and EPR.Additional Material: 5 Ill.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesBuback, M. ; Garcia-Rubio, L. H. ; Gilbert, R. G. ; Napper, D. H. ; Guillot, J. ; Hamielec, A. E. ; Hill, D. ; O'Driscoll, K. F. ; Olaj, O. F. ; Shen, Jiacong ; Solomon, D. ; Moad, G. ; Stickler, M. ; Tirrell, M. ; Winnik, M. A.
New York : Wiley-Blackwell
Published 1988Staff ViewISSN: 0887-6258Keywords: Chemistry ; Polymer and Materials ScienceSource: Wiley InterScience Backfile Collection 1832-2000Topics: Chemistry and PharmacologyAdditional Material: 1 Ill.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesFarinha, J. P. S. ; Martinho, J. M. G. ; Xu, H. ; Winnik, M. A. ; Quirk, R. P.
Bognor Regis [u.a.] : Wiley-Blackwell
Published 1994Staff ViewISSN: 0887-6266Keywords: cyclization ; fluorescence ; polystyrene ; hydrogen bonding ; Chemistry ; Polymer and Materials ScienceSource: Wiley InterScience Backfile Collection 1832-2000Topics: Chemistry and PharmacologyPhysicsNotes: Cyclization of a polystyrene chain (Mn = 10,600; Mw/Mn = 1.09) both ends labeled with 4-(1-pyrenyl)butanoamide groups was studied in cyclohexane between 25 and 95°C. The amide groups (peptide bonds) at both ends can form an intrachain hydrogen bond between the amide hydrogen at one chain end and the carbonyl oxygen at the other. The presence of two sets of conformers, random coils, and chains cyclized through hydrogen bonding, complicates the data analysis. The pyrene excimer kinetics of this polymer is well described by a model composed of two monomers (hydrogen bonded and nonbonded chains) and one excimer, in equilibrium. The cyclization rate constant for hydrogen-bonded chains is larger than the one for nonhydrogen-bonded chains. The pyrene excimer binding energy (ca. 1.6 kcal/mol) is lower than the published value for nonhydrogen-bonded chains (∼ 9 kcal/mol), suggesting that intrachain hydrogen bonding hinders the stabilization of the excimer. © 1994 John Wiley & Sons, Inc.Additional Material: 8 Ill.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesStaff View
ISSN: 0030-493XKeywords: Chemistry ; Analytical Chemistry and SpectroscopySource: Wiley InterScience Backfile Collection 1832-2000Topics: Chemistry and PharmacologyNotes: A review of the literature indicates compelling evidence that: (1) loss of ROH from esters requires protonation of the alkoxy oxygen; (2) the (symmetry forbidden) [1,3] hydrogen migration from protonated carbonyl to alkoxy oxygen does not occur in the mass spectra of esters; (3) hydrogen abstraction in esters occurs almost exclusively to the carbonyl oxygen. Mechanisms are proposed which account for all examples of ROH loss from esters. Alkanol loss from molecular ions in esters requires the presence of a second functional group to act as an intramolecular catalyst, either as a general acid in transferring a proton to the alkoxy oxygen, or as a general base in assisting the [1,3] carbonyl oxygen to alkoxy oxygen proton transfer. Loss of ROH from fragment ions requires proton transfer from an atom α to the positive charge to the alkoxy oxygen. These mechanisms are generalized to include a wide class of bifunctional esters and a selection of natural products.Type of Medium: Electronic ResourceURL: