Anisotropic nanoparticles of precise microstructure polyolefins

Trzaskowski, Justyna; Rabe, Christian; Vogtt, Karsten; Krumova, Marina; Goerigk, G.; Ballauff, Matthias; Mecking, Stefan

doi:10.1039/c2cc32834h

Cited by 3 publications

(3 citation statements)

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“…However, discriminating between growth and nucleation in the Avrami equation is not straightforward, and the intensity of the supercooling at high degree of confinement remains the best proof of the occurrence of homogeneous nucleation. Recently, extremely large supercooling of PE single lamellae has been achieved. , The authors observed that the crystallization temperature evolved as a function of the crystal thickness. The relationship between the crystallization temperature and the crystal thickness was given by Strobl and implies the existence of an intermediate phase (mesomorphic phase) along the crystallization pathway.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, extremely large supercooling of PE single lamellae has been achieved. 33,34 The authors observed that the crystallization temperature evolved as a function of the crystal thickness. The relationship between the crystallization temperature and the crystal thickness was given by Strobl and implies the existence of an intermediate phase (mesomorphic phase) along the crystallization pathway.…”

Section: ■ Introductionmentioning

confidence: 99%

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Crystallization of Nanodomains in Polyethylene Latexes

et al. 2017

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Semi-crystalline polyethylene (PE) nanoparticles were obtained by free radical emulsion polymerization under mild conditions of pressure and temperature. At high surfactant concentration, the obtained anisotropic nanoparticles exhibit a strong degree of supercooling. This paper explores the relationship between the morphology of such particles and their high degree of supercooling. The shape anisotropy of the semi-crystalline PE particles already observed by transmission electron microscopy was confirmed by dynamic light scattering with the autocorrelation function containing both translational and rotational diffusion coefficients as well as by in situ synchrotron small-angle and wide-angle X-ray scattering (SAXS/WAXS). Temperature-resolved synchrotron scattering was used to further characterize the evolution of particles morphology and crystallinity during cooling. Paying special attention to the role of the surfactant we propose a novel mechanism which contributes to a better understanding of the crystallization of PE nanoparticle. The observed supercooling might be the result of the Coulomb repulsion between the surfactant head groups present at the particle surface, which hinders the particle contraction upon crystallization. The high surface charge density prevents the reduction of the particle surface, thus forcing a morphological transition from sphere to oblate ellipsoid during crystallization. This mechanism would act as potential barrier to the crystallization, resulting in supercooling.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Crystallization of Nanodomains in Polyethylene Latexes

et al. 2017

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“…In this regard polyethylene (PE) is of particular interest, since it is the prototype of a crystalline polymer and its crystallization behavior has been studied intensely in the past . Different methods have been developed for the synthesis of anisotropic PE single crystal nanoparticles with variable size and shape, such as insertion polymerization of ethylene in aqueous surfactant solution, free-radical emulsion polymerization at intermediate pressures, crystallization of the hydrophobic core of micelles formed from diblock copolymers with a PE and a hydrophilic block, self-assembly of linear ethylene–acrylic acid copolymers in aqueous solution, and crystallization of precisely branched linear polyethylene in nanoscale droplets . An analysis of such nanoparticles composed of linear polyethylene by a combination of cryo-TEM and SAXS revealed these to be polymer single crystals composed of one lamella and with an extension of only a few tens of nanometers also in the lateral direction (cf.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Polyethylene Nanocrystals Labeled with a Single Fluorescent Dye Molecule: Toward Monitoring of Nanoparticle Orientation

et al. 2013

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The three-dimensional orientation monitoring of anisotropic nanoparticles during dynamic processes is a fundamental issue. Herein we show that incorporation of a single fluorescent reporter molecule is a promising concept toward this goal. As a model system, shape anisotropic single lamella polyethylene (PE) nanocrystals bearing one single fluorescent reporter molecule were prepared via ring-opening metathesis polymerization (ROMP) of highly ring-strained trans-cyclooctene ( tr COE) using a mixture of a dye-functionalized ruthenium-based initiator (1; perylene diimide (PDI) substituted Hoveyda−Grubbs second generation Ru alkylidene) and an appropriate excess of the unlabeled analogue (2; Hoveyda−Grubbs second generation Ru alkylidene) in aqueous microemulsion as a key step and subsequent exhaustive hydrogenation (>99.9%) of the main-chain unsaturated polymer in the nanoparticles to yield nanocrystals of high molecular weight, strictly linear PE (M n = 8 × 10 5 g mol −1 ; M w /M n = 1.4). TEM and AFM show a particle thickness of ca. 12 nm with a lateral extension of typically 45 nm. Comparable initiation kinetics of both complexes 1 and 2, which is a key requirement for this approach, were revealed by fluorescence spectroscopy studies (ΔH ‡ = 57.4 kJ mol −1 , ΔS ‡ = −73.0 J mol −1 K −1 for 1 vs ΔH ‡ = 63.6 kJ mol −1 , ΔS ‡ = −80.8 J mol −1 K −1 for 2 for the initiation with n-butyl vinyl ether, respectively). The labeled nanocrystals were characterized by means of single molecule fluorescence spectroscopy. Orientational analysis via defocused wide-field fluorescence microscopy (DWFM) revealed a fixed orientation of the chromophores within the nanocrystals, with their long molecular axis predominantly oriented parallel to the polar axis of the nanoparticles.

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The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2012

Herndon¹

2014

Coordination Chemistry Reviews

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Anisotropic nanoparticles of precise microstructure polyolefins

Abstract: Nanoparticles of precisely branched polyethylenes possess a distinct oblate shape resulting from a crystalline lamella in the particle as revealed by SAXS and TEM, and display controllable and well-behaved thermal behaviour.

Cited by 3 publications

References 20 publications

Crystallization of Nanodomains in Polyethylene Latexes

Crystallization of Nanodomains in Polyethylene Latexes

Anisotropic Polyethylene Nanocrystals Labeled with a Single Fluorescent Dye Molecule: Toward Monitoring of Nanoparticle Orientation

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2012

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