Single lamella nanoparticles of polyethylene
| Autor: | Stefan Mecking, Arnaud Chiche, Sabine Rosenfeldt, Christa H. M. Weber, Matthias Ballauff, Qiong Tong, Ludger Harnau, Georg Krausch, Inigo Göttker-Schnetmann |
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| Rok vydání: | 2007 |
| Předmět: |
Materials science
Nanoparticle Bioengineering chemistry.chemical_compound Microscopy Electron Transmission X-Ray Diffraction Scattering Small Angle General Materials Science chemistry.chemical_classification Small-angle X-ray scattering Mechanical Engineering Cryoelectron Microscopy General Chemistry Polymer Polyethylene Condensed Matter Physics Amorphous solid Crystallography Lamella (surface anatomy) chemistry Polymerization Chemical engineering Transmission electron microscopy ddc:540 Nanoparticles |
| Zdroj: | Nano letters. 7(7) |
| ISSN: | 1530-6984 |
| Popis: | We present a complete analysis of the structure of polyethylene (PE) nanoparticles synthesized and stabilized in water under very mild conditions (15 degrees 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 degrees 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. |
| Databáze: | OpenAIRE |
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