Crystallization kinetics and the fine morphological evolution of poly(ethylene oxide)/ionic liquid mixtures

The overall crystallization kinetics and spherulite morphologies of miscible poly(ethylene oxide) (PEO)/1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) mixtures were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and rheological measurements. T...

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Bibliographic Details
Published in:Chinese journal of polymer science 2017-11, Vol.35 (11), p.1402-1414
Main Authors: Li, Wen-ze, Niu, Yan-hua, Zhou, Chen-ting, Luo, Huan, Li, Guang-xian
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Condensed Matter Physics
Crystal growth
Crystal structure
Crystallization
Dilution
Ethylene oxide
Heat measurement
Industrial Chemistry/Chemical Engineering
Ionic liquids
Ions
Optical microscopy
Polymer Sciences
Rheological properties
Small angle X ray scattering
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Summary:The overall crystallization kinetics and spherulite morphologies of miscible poly(ethylene oxide) (PEO)/1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) mixtures were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and rheological measurements. The finer crystal structures were further detected by wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS). Crystallization of PEO is largely suppressed by [BMIM][PF 6 ] addition especially at higher ionic liquid (IL) concentrations above 20 wt%. Both the overall crystallization rate and the spherulite growth decrease with the increase of IL content and crystallization temperature; however, the crystallization mechanism keeps unchanged as evidenced by the similar Avrami exponent n and WAXD results. The addition of [BMIM][PF 6 ] could induce more nuclei to some extent, but the induction time of crystallization is evidently prolonged, and a linear to non-linear transition of the spherulite growth ( R ∝ t to R ∝ t 1/2 ) can be observed. At higher IL concentration, the spherulite texture changes apparently from particular serrated to branch surface due to the diffusion-controlled growth and the dilution effect, which also as a main factor contributes to the increasing trend of the long period of crystals.
ISSN:0256-7679
1439-6203
DOI:10.1007/s10118-017-1997-3