Formation of Oriented Polar Crystals in Bulk Poly(vinylidene fluoride)/High-Aspect-Ratio Organoclay Nanocomposites
| Autor: | Kiriaki Chrissopoulou, Adam Kiersnowski, Markus Mezger, Ingo Lieberwirth, Dorota Chlebosz, Spiros H. Anastasiadis, Michael Ryan Hansen, Philipp Selter, Veijo Honkimäki, Binyang Hou |
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| Rok vydání: | 2018 |
| Předmět: |
Nanocomposite
Materials science 02 engineering and technology Surfaces and Interfaces 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences law.invention chemistry.chemical_compound Montmorillonite chemistry Chemical engineering law Phase (matter) Electrochemistry Organoclay Polar General Materials Science Extrusion Crystallization 0210 nano-technology Fluoride Spectroscopy |
| Zdroj: | Langmuir. 34:13375-13386 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/acs.langmuir.8b02412 |
| Popis: | We have investigated the formation of lamellar crystals of poly(vinylidene fluoride) (PVDF) in the presence of oriented clay particles with different aspect ratios (ARs) and surface properties. Hot-melt screw extrusion of PVDF with 5 wt % of montmorillonite (AR ≈ 12) or fluoromica (AR ≈ 27) resulted in formation of phase-separated blends. Replacing the clays with their organoclay derivatives, organomontmorillonite or organofluoromica, resulted in the corresponding intercalated nanocomposites. The organoclays induced formation of polar β- and γ-polymorphs of PVDF in contrast to the α-polymorph, which dominates in the pure PVDF and the PVDF/clay blends. Solid-state nuclear magnetic resonance revealed that the content of the α-phase in the nanocomposites was never higher than 7% of the total crystalline phase, whereas the β/γ mass ratio was close to 1:2, irrespective of the AR or crystallization conditions. X-ray diffraction showed that the oriented particles with a larger AR caused orientation of the polar lamellar crystals of PVDF. In the presence of the organofluoromica, PVDF formed a chevron-like lamellar nanostructure, where the polymer chains are extended along the extrusion direction, whereas the lamellar crystals were slanted from normal to the extrusion direction. Time-resolved X-ray diffraction experiments allowed the identification of the formation mechanism of the chevron-like nanostructure. |
| Databáze: | OpenAIRE |
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