Structural study of polymer blends by fluorescence spectroscopy

Atvars, Teresa Dib Zambon; Esteban, Irène; Illera, B.; Serrano, Berna; Vigil, M Reyes; Piérola, Inés F.

doi:10.1016/s0022-2313(96)00146-9

Cited by 20 publications

(33 citation statements)

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“…11,12 The polymer local dynamics as well as the structural properties and relaxation processes of polymer and blends were studied by steady state and dynamic fluorescence using anthranyl and pyrenyl groups. [13][14][15] Fluorescence studies of polymethacrylic acid (PMAA) and polyacrylic acid (PAA) containing aromatic fluorescent probes such as naphthalene, anthracene and pyrene have been carried out by many authors to elucidate the properties of those polyelectrolytes in different solvents, pH, and surfactant addition. [16][17][18][19][20] Fluorescence anisotropy reflects the microviscosity and the solubilization dynamics of the probe molecule in solutions of polyelectrolytes.…”

Section: Introductionmentioning

confidence: 99%

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Oliveira¹,

Gehlen²

2003

J. Braz. Chem. Soc.

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Soluções de poli(ácido metacrílico) atático, PAMA com peso molecular na faixa de (1,6 a 3,4) x 10 5 g mol -1 , e com corantes fluorescentes 9-aminoacridina ou azul do nilo ligados à cadeia, foram estudados por medidas fotofísicas em função da viscosidade e polaridade do solvente. O comportamento dos segmentos da cadeia do PAMA nas vizinhanças da sonda fluorescente foi descrito pela mudança na rotação difusional dos corantes. O etilenoglicol expande a cadeia polimérica quando comparada com a forma mais compactada do corante-PAMA em 50% água/etilenoglicol. A variação do tempo de relaxação rotacional do corante ligado ao PAMA indica uma expansão progressiva da cadeia polimérica para uma forma aberta em etilenoglicol.Solutions of atactic poly(methacrylic acid), PMAA, with molecular weights in the range of (1.6 to 3.4) x 10 5 g mol -1 , and labeled with the fluorescent dyes 9-aminoacridine or Nile blue were studied by photophysical measurements as a function of solvent viscosity and polarity. The conformational behavior of the PMAA chain segments around the fluorescent probe was reported by the change in the rotational diffusion of the dyes. Ethylene glycol swells the polymer chain compared with the more contracted conformation of PMAA in 50% water/ethylene glycol. The change in the rotational relaxation time of the dye bound to PMAA with the decrease of water content in the solvent mixture indicates a progressive expansion of polymer chain to a more open coil form in solution.Keywords: dyes, polyelectrolytes, PMAA, rotational diffusion, solvent friction IntroductionPhotophysical studies of polymers in solution have been extensively reported in recent years. 1,2 Time resolved fluorescence spectroscopy (TRFS) was found to be particularly useful in the study of several types of polymers in solution, and in the presence of additives. 3-10 Time resolved anisotropy decay of a fluorescent probe attached to a polymer chain reflects the rotational relaxation of the probe, and the local dynamics of the polymer segments in solution. 2 The dependence of the segmental dynamics as a function solvent viscosity was studied by TRFS using anthracene attached to 1,2 polybutadiene. 11,12 The polymer local dynamics as well as the structural properties and relaxation processes of polymer and blends were studied by steady state and dynamic fluorescence using anthranyl and pyrenyl groups. [13][14][15] Fluorescence studies of polymethacrylic acid (PMAA) and polyacrylic acid (PAA) containing aromatic fluorescent probes such as naphthalene, anthracene and pyrene have been carried out by many authors to elucidate the properties of those polyelectrolytes in different solvents, pH, and surfactant addition. [16][17][18][19][20] Fluorescence anisotropy reflects the microviscosity and the solubilization dynamics of the probe molecule in solutions of polyelectrolytes. Reports in the literature using polarization and anisotropy of rhodamine 6 G in ethylene glycol demonstrate that the depolarization properties of the probe have relations with the solv...

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Section: Introductionmentioning

confidence: 99%

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Oliveira¹,

Gehlen²

2003

J. Braz. Chem. Soc.

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“…Among those physical properties of the environment only some of them may control the photophysics of An groups: local viscosity or rigidity. [5][6][7] It is known that in amorphous polymers some flexible-like or liquid-like sites where side chain motions are allowed, may coexist, far below the T g , with solid-like domains. From the analysis of the fluorescence decay of a probe (malachite green) in several polymer matrices, with biexponential functions, it was concluded 17 that the fast decay component arises from sites where phenyl or ester side groups freely rotate in the matrix with relatively small activation energy and therefore small changes with decreasing temperature with respect to T g .…”

Section: Resultsmentioning

confidence: 99%

“…2 As a consequence of the probe-polymer matrix interaction the fluorescence intensity changes with temperature following and revealing polymer relaxation processes. 5 Matrix effects on the radiationless deactivation of substituted anthracenes were also observed in films of poly(methylmethacrylate) (PMMA) and they were attributed to competing intersystem crossing and very fast internal conversion. 6 For 9-methylanthracene, 7 the radiationless deactivation rate coefficients are dominated by Franck Condon factors in two types of coordinates: those of small groups such as protons with solvent independent dynamics and those of larger groups whose rate constants are inversely proportional to the viscosity showing relevant matrix effects.…”

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confidence: 99%

“…Time resolved fluorescence measurements, may also provide useful information on the microstructure of polymer samples in bulk. 13,16,17,27 Common fluorescent molecules in non-viscous homogeneous dilute solution and in the absence of excimer or exciplex formation give single exponential decays in the nanosecond time range. Such is the case of 9-anthrylmethylmethacrylate (MMA-An) in dioxane dilute solution which yields a fluorescence lifetime of 4.56 ns, 13 a very close value to that previously reported for the model compound, 9-methylanthracene, 4.6 ns.…”

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Fluorescence Lifetime Distributions of Labeled Amorphous Polymers in Bulk

Serrano¹,

Baselga²,

Piérola³

2002

Polym J

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ABSTRACT:Polystyrene, poly(methylmethacrylate), poly(cyclohexyl methacrylate) and poly(1-butylmethacrylate) were labeled with anthryl groups by copolymerization. Films of labeled polymers as well as blends of them with unlabeled polystyrene samples of different polydispersity and molecular weight, were prepared by solvent casting. The time resolved emission of anthryl groups in those films was measured by Single Photon Counting with front face excitation at the standard 30• incident angle and with much lower incident angles to photoselect chromophores on the polymer-air surface. Fluorescence decays were fitted with bimodal fluorescence lifetime distributions, which were analyzed taking into consideration some polymer characteristics and the compatibility of polymer blends. It was thus concluded that solid-like and liquid-like environments are both in the bulk and in the surface of the film although liquid-like domains are more frequent on the surface than in bulk. Polymer T g determines the position of the two modes and polydispersity justify the broadness of the modes in the fluorescence lifetime distribution. KEY WORDS Fluorescence Lifetime Distribution / Fluorescence Decay / Poly(1-butylmethacrylate) / Poly(methylmethacrylate) / Poly(cyclohexylmethacrylate) / Polystyrene / Steady state or time-resolved fluorescence measurements of chromophores added to polymers as probes or labels can yield valuable information on the structural or dynamic properties of the system. 1 Anthryl groups have been broadly employed as polymer labels due to its well known photophysical behavior as well as to its relatively small size and high fluorescence quantum yield. 2, 3 Nevertheless, it was found 4 that the chain mobility of polystyrene (PS) is slightly reduced by the steric hindrance of the anthryl group with phenyl rings and therefore, minimum proportions of labeling groups must be introduced in the polymer to preserve unmodified the macroscopic polymer characteristics. Fortunately, due to the very high sensitivity of this technique, only very low chromophore concentrations are needed, which does not disturb the system properties. But even such low concentrations still report on its environment and on processes occurring in the nanosecond time range.It was shown 2 for anthracene dissolved in PS that rigidity and dimension of the matrix free volume are related with the vibronic structure of the fluorescence spectrum. The non-radiative deactivation processes, which involve out of plane vibrational modes and intermolecular interactions, are inhibited in polymer matrices. 2 As a consequence of the probe-polymer matrix interaction the fluorescence intensity changes with temperature following and revealing polymer relaxation processes. 5 Matrix effects on the radiationless deactivation of substituted anthracenes were also observed in films of poly(methylmethacrylate) (PMMA) and they were attributed to competing intersystem crossing and very fast internal conversion. 6 For 9-methylanthracene, 7 the radiationless deactivation rate coe...

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“…54,55 Moreover, because the donor and acceptor emissions are of distinct colors (blue and red, respectively), epifluorescence microscopy (EFM) is a very useful tool for both morphological characterization and in situ chemical analysis for identifying every domain of the polymer blend by differences in the color. [48][49][50][51] The morphological studies were further detailed by scanning electron microscopy (SEM). …”

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confidence: 99%

Probing interchain interactions in emissive blends of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] with polystyrene and poly(styrene-co-2-ethylhexyl acrylate) by fluorescence spectroscopy

Andrade¹,

Atvars²

2006

J. Braz. Chem. Soc.

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Nesse trabalho foram realizados estudos dinâmicos e estáticos de fotoluminescência de blendas poliméricas do poli[2-metóxi-5-(2'-etilexiloxi)-p-fenileno vinileno] (MEH-PPV) com poliestireno-co-2-co-metacrilato de metila1-1-pirenila e seu copolímero poli(estireno-co-acrilato de 2-etilexila-co-1-metacrilato de metila1-1-pirenila) (com 9 mol% e 19 mol% de unidades acrilato de 2-etilexila unidades e 0,06 mol% de 1-pirenila). O poliestireno marcado com pirenilo e alguns de seus copolímeros foram sintetizados por polimerização em emulsão e caracterizados por 13 C e 1 H NMR, FTIR, GPC, DSC e UV-Vis. Os filmes foram preparados por deposição centrífuga a partir de soluções em clorofórmio, sendo a composição das blendas de 0,1, 0,5, 1,0, e 5,0 m/m% de MEH-PPV. A miscibilidade desses sistemas foi estudada através dos processos de transferência não-radiativa de energia entre o grupo 1-pirenila (doadores de energia) e o MEH-PPV (receptor de energia). A intensidade relativa de emissão e os tempos de decaimento de fluorescência do doador mostraram que a miscibilidade do MEH-PPV e dos copolímeros e maior do que entre o MEH-PPV e o poliestireno o que foi confirmado por microscopia óptica de epifluorescência e por microscopia eletrônica de varredura.We present dynamic and static photoluminescence studies on polymer blends of conjugated poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) with polystyrene-co-1-pyrenyl methyl methacrylate and its copolymer poly(styrene-co-2-ethylhexyl acrylate-co-1-pyrenylmethyl methacrylate) (with 9 mol% and 19 mol% of 2-ethylhexyl acrylate units and 0.06 mol% of 1-pyrenyl). Pyrenyl-labeled polystyrene and its copolymers were synthesized by emulsion polymerization and characterized by 13 C and 1 H-NMR, FTIR, GPC, DSC, and UVVis. Spin-coating films of the blends were prepared from chloroform solutions with 0.1, 0.5, 1.0, and 5.0 wt% of MEH-PPV. The miscibility of these systems was studied by non-radiative energy transfer processes between the 1-pyrenyl moieties (the energy donor) and MEH-PPV (the energy acceptor). The relative emission intensities and the fluorescence lifetimes of the donor showed that the miscibility of MEH-PPV and the copolymers is greater than that of MEH-PPV and polystyrene and this was confirmed by epifluorescence optical microscopy and scanning electron microscopy.Keywords: poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV), blends, miscibility, copolymer poly(styrene-co-2-ethylhexyl acrylate-co-1-pyrenylmethyl methacrylate), fluorescence, energy transfer IntroductionConjugated polymers are the subject of considerable scientific attention because they constitute attractive components for application as emissive materials in electroluminescent devices and, in particular, as organic light-emitting diodes (OLED).1 Such interest is attributed to their superior processability and flexibility relative to inorganic compounds, greater possibility of preparation of materials with distinct emission colors, electroluminescence emission with low turn-on volt...

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Structural study of polymer blends by fluorescence spectroscopy

Cited by 20 publications

References 1 publication

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

Fluorescence Lifetime Distributions of Labeled Amorphous Polymers in Bulk

Probing interchain interactions in emissive blends of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] with polystyrene and poly(styrene-co-2-ethylhexyl acrylate) by fluorescence spectroscopy

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