Energy Transfer in Restricted Geometry:  Polyisoprene−Poly(methyl methacrylate) Block Copolymer Interfaces

The use of nonaqueous emulsions to synthesize particles by ROMP is described. The applied emulsions – consisting of two immiscible, organic, aprotic solvents – are versatile reaction systems for the preparation of polymer particles from moisture sensitive monomers and catalysts. Whereas up to now only polycondensations or polyadditions have been utilized in nonaqueous emulsions, catalytic polymerizations are now presented. Four different functionalized norbornene derivatives were applied for ROMP by a second‐generation Grubbs catalyst to form polymer nanoparticles. Furthermore, core/shell and surface functionalized nanoparticles applicable to “click” reactions were prepared to demonstrate the use of different polymerization procedures in one pot.magnified image

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“…[19,20] The critical micelle concentration (CMC) was determined to be 9 Á 10 --7 mol Á L À1 (5 Á 10 À2 g Á L À1 ).…”

Section: Experimental Partmentioning

confidence: 99%

Nanoparticles by ROMP in Nonaqueous Emulsions

Haschick¹,

Klapper²,

Wagener³

et al. 2010

Macro Chemistry & Physics

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“…Here the emission is only from the An-labeled polymer at a wavelength 350-355 nm where no anthracene emission occurs. Because of concerns that this emission might arise because of sample aging or because of the substantial amount of antioxidant added by Ni [10][11][12] to samples prepared previously in this laboratory, we prepared new samples, exercising care to ensure that the 2-substituted anthracene derivative used here was free of its 1-substituted isomer. 21 We refer to these samples as PI-9Phe-PMMA and PI-2An-PMMA, respectively.…”

Section: Introductionmentioning

confidence: 99%

Energy Transfer Study of the Interface Thickness in Symmetrical Isoprene−Methyl Methacrylate Diblock Copolymers

Yang¹,

Lü²,

Rharbi³

et al. 2003

Macromolecules

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We describe direct nonradiative energy transfer (DET) experiments on mixtures of two symmetrical poly(isoprene-b-methyl methacrylate) block copolymers of similar molar mass and composition, bearing different dyes at the junction. One polymer has a donor dye (9-phenanthrene) at the junction, and the other has an acceptor dye (2-anthracene). Small-angle X-ray scattering experiments show that films of the mixed diblock copolymers have a lamellar morphology with a spacing that varies with composition from 24 to 26 nm. Fluorescence decay profiles from these films were analyzed in terms of an energy transfer model that takes account of the distribution of junctions across the interface. On the basis of the value R 0 ) 2.3 nm for the characteristic ET distance and an assumed value of 〈κ 2 〉 ) 0.476 for the preaveraged orientation parameter for randomly oriented immobile dipoles, we calculate an interface thickness of 1.6 ( 0.1 nm. This value is independent of the acceptor/donor ratio (i.e., the acceptor concentration) in the films.

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“…All samples contain 1 wt % 2,6-di-tertbutyl-4-methylphenol as an antioxidant. The antioxidant does not disturb the fluorescence measurement 20 and is carried through all steps of sample preparation. The diblock copolymer blends were prepared from samples listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…A technical requirement of our experiment is that in each sample the ratio of [A/D] g 1. [17][18][19][20] Thus, two pairs of samples are needed to cover the entire composition range.…”

Section: Introductionmentioning

confidence: 99%

Energy Transfer Studies of Binary Block Copolymer Blends. 1. Effect of Composition on the Interface Area per Chain and the Lamellar Size

Tcherkasskaya

Winnik

1997

Macromolecules

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Binary blends of polyisoprene-poly(methyl methacrylate) PI-PMMA diblock copolymers with a common PMMA length and different lengths of polyisoprene blocks were prepared from samples containing a single fluorescent dye, either phenanthrene (donor) or anthracene (acceptor), at the junction point. The two pure block copolymers and their mixtures were studied by the direct energy transfer (DET) technique. All experiments point to intimate mixing of the samples over the entire composition range. These DET experiments yield the interphase volume per junction vj and/or the ratio R/δ of the microdomain size R to the interphase thickness δ, as a function of the composition of the block copolymer mixture. Since, for these strongly segregated chains, the interface thickness is invariant with chain length and should also be constant for this set of mixtures, we can calculate from vj and R/δ the interface area per chain and the period spacing R. Here we find that addition of up to 25 mol % of the second polymer has no effect on the lamellar longitudinal period spacing determined by the length of the major component. Changes in the structure of the binary blend occur only between these compositions.

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Energy Transfer in Restricted Geometry: Polyisoprene−Poly(methyl methacrylate) Block Copolymer Interfaces

Cited by 32 publications

References 43 publications

Nanoparticles by ROMP in Nonaqueous Emulsions

Nanoparticles by ROMP in Nonaqueous Emulsions

Energy Transfer Study of the Interface Thickness in Symmetrical Isoprene−Methyl Methacrylate Diblock Copolymers

Energy Transfer Studies of Binary Block Copolymer Blends. 1. Effect of Composition on the Interface Area per Chain and the Lamellar Size

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