Catalytic Polymerization of Ethylene in Emulsion

Soula, R.; Novat, Christian; Tomov, Atanas K.; Spitz, Roger; Claverie, Jérôme P.; Drujon, Xavier; Malinge, Jean; Saudemont, T.

doi:10.1021/ma0017135

Cited by 128 publications

(92 citation statements)

References 36 publications

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“…2 Recently, it was demonstrated that ethylene can be polymerized in aqueous systems in a catalytic fashion by Ni(II) complexes. [3][4][5][6] By virtue of this novel synthesis, long chains of polyethylene can be generated in a well-controlled environment and at ambient temperature. Thus, it could be shown that aqueous PE dispersions can be produced.…”

Section: Introductionmentioning

confidence: 99%

Single Lamella Nanoparticles of Polyethylene

Weber¹,

Chiche²,

Krausch³

et al. 2007

Nano Lett.

118

142

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We present a complete analysis of the structure of polyethylene (PE) nanoparticles synthesized and stabilized in water under very mild conditions (15°C, 40 atm) by a nickel-catalyzed polymerization in aqueous solution. Combining cryogenic transmission electron microscopy (cryo-TEM) with X-ray scattering, we demonstrate that this new synthetic route leads to a stable dispersion of individual PE nanoparticles with a narrow size distribution. Most of the semicrystalline particles have a hexagonal shape (lateral size 25 nm, thickness 9 nm) and exhibit the habit of a truncated lozenge. The combination of cryo-TEM and small-angle X-ray scattering demonstrates that the particles consist of a single crystalline lamella sandwiched between two thin amorphous polymer layers ("nanohamburgers"). Hence, these nanocrystals that comprise only ca. 14 chains present the smallest single crystals of PE ever reported. The very small thickness of the crystalline lamella (6.3 nm) is related to the extreme undercooling (more than 100°C) that is due to the low temperature at which the polymerization takes place. This strong undercooling cannot be achieved by any other method so far. Dispersions of polyethylene nanocrystals may have a high potential for a further understanding of polymer crystallization as well as for materials science as, e.g., for the fabrication of extremely thin crystalline layers.Polyethylene (PE) is a commodity polymer that has become ubiquitous over the past several decades because of its low price and good mechanical properties. 1 Hence, the number of applications of the material is huge and many millions of tons are produced worldwide annually. However, PE has hardly played any role in the field of nanotechnology. This is due to the problem that PE is produced either by free radical polymerization under high pressure and temperature or with metal-organic catalysts working exclusively under strictly water-free conditions. Polymer nanoparticles and their composites with inorganic compounds, however, are very often produced in aqueous systems. 2 Recently, it was demonstrated that ethylene can be polymerized in aqueous systems in a catalytic fashion by Ni(II) complexes. [3][4][5][6] By virtue of this novel synthesis, long chains of polyethylene can be generated in a well-controlled environment and at ambient temperature. Thus, it could be shown that aqueous PE dispersions can be produced. This novel way of polymerization hence opens the way for the creation of nanostructures made from PE. Up to now, the particles synthesized in this way were semicrystalline and for the largest part consisted of stacks of several crystalline lamellae. 6

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Section: Introductionmentioning

confidence: 99%

Single Lamella Nanoparticles of Polyethylene

Weber¹,

Chiche²,

Krausch³

et al. 2007

Nano Lett.

118

142

View full text Add to dashboard Cite

show abstract

“…The average particle sizes of the dispersions obtained by this procedure are typically in the range from 100 to 500 nm. [45][46][47][48][49]63 The preparation of dispersions with solids contents of up to 30 % has been reported. 46,47 Catalyst activities of up to 1.7×10 5 TO h -1 have been published to date for the preparation of polyethylene dispersions.…”

Section: Polyolefin Dispersionsmentioning

confidence: 99%

Polymer dispersions from catalytic polymerization in aqueous systems

Mecking

2006

Colloid Polym Sci

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By contrast to traditional free radical emulsion polymerization, catalytic polymerization allows for polymer microstructure control. In terms of monomers polymerizable, both techniques are largely complementary. Since the beginning of this decade, an increasing number of reports on polyolefin, polybutadiene, polyalkenamer, polynorbornene, polyketone and polyacetylene dispersions prepared by catalytic polymerization in disperse aqueous systems has appeared. This contribution reviews the preparation of these dispersions, their colloidal properties, particle formation mechanisms, particle morphologies and polymer microstructures.

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“…[30,31] Regarding polymer particle formation in the ethylene polymerization with a catalyst miniemulsion, it can be assumed that in the case of semicrystalline polymer the latter precipitates in the miniemulsion droplets rapidly, forming new particles. Average particle sizes in the range of 70 nm to 1 mm have been reported, [12][13][14][15][16] as determined by light scattering (note, however, that the particles of linear polyethylene are not spherical as observerd by TEM and AFM [32] ). For the case of low-crystalline (and in the example studied also low molecular-weight) ethylene-1-olefin copolymers, which have a much higher miscibility with the organic phase present in the miniemulsion droplets (in this case 1-olefin copolymer and some aromatic solvent), Claverie et al have shown that the number of polymer particles obtained is equal to the number of miniemulsion droplets initially present.…”

Section: Polymerization With Catalyst Miniemulsionsmentioning

confidence: 99%

“…[13] Crystallinity can be reduced by copolymerization, albeit at a further expense of molecular weight and also reduced catalyst activities by comparison to ethylene homopolymerization. [14,15] Polymerization with well-defined complexes as a catalyst precursor as well as with in situ prepared catalysts has been studied.…”

mentioning

confidence: 99%