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4-Miktoarm star architecture induces PVDF β-phase formation in (PVDF)2-b-(PEO)2 miktoarm star copolymers
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2020-09-09 , DOI: 10.1039/d0tc03192e
Nicolás María 1, 2, 3, 4, 5 , Jon Maiz 1, 2, 3, 4, 5 , Valentin Rodionov 6, 7, 8 , Nikos Hadjichristidis 9, 10, 11, 12, 13 , Alejandro J. Müller 1, 2, 3, 4, 5
Affiliation  

Novel (PVDF)2-b-(PEO)2 4-miktoarm star copolymers (PVDF: polyvinylidene fluoride, PEO: polyethylene oxide) with three different compositions, but the same overall molecular weight, were synthesized by combining iodine transfer and anionic polymerizations with “click” chemistry. We have studied the polymorphic character of the PVDF arm crystals in the 4-miktoarm star copolymers in comparison with one of their 2-arm star (linear) precursors ((PVDF29-N3)2), when the samples are cooled from the melt at different cooling rates. The phase behaviour was investigated by small angle X-ray scattering (SAXS) and polarized light optical microscopy (PLOM). The results indicate that the materials are either weakly segregated in the melt or melt-mixed. They form PVDF spherulites at high crystallization temperatures when the PEO component is molten. The relative contributions of the α and β-phase were determined by in situ wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. All samples exhibit a mixture of α and β-phase crystals when cooled from the melt at 20 °C min−1. However, the amount of β-phase is much larger in the 4-miktoarm star copolymer samples than in the (PVDF29-N3)2 linear precursor. Therefore, the 4-miktoarm star chain topology was found to induce β-phase formation. As the samples are cooled at slower rates, the amount of PVDF β-phase crystals increased. For samples crystallized at 1 °C min−1, the PVDF arms of all the synthesized (PVDF)2-b-(PEO)2 miktoarm star copolymers form exclusively the ferroelectric/piezoelectric β-phase crystals. Therefore, these materials have potential applications in the field of energy harvesting.

中文翻译:

4-Miktoarm星形结构在(PVDF)2-b-(PEO)2 miktoarm星形共聚物中诱导PVDFβ相形成

通过碘转移和阴离子聚合的结合,合成了具有三种不同组成,但总分子量相同的新型(PVDF)2 - b-(PEO)2 4- to星形共聚物(PVDF:聚偏氟乙烯,PEO:聚环氧乙烷)。 “点击”化学。我们已经研究了4-miktoarm星型共聚物中PVDF臂晶体的多态性与其2个星型星形(线性)前体之一((PVDF 29 -N 32),以不同的冷却速率从熔体中冷却样品。通过小角度X射线散射(SAXS)和偏振光光学显微镜(PLOM)研究了相行为。结果表明材料在熔体中微弱地偏析或熔体混合。当PEO组分熔化时,它们在高结晶温度下形成PVDF球晶。α和β相的相对贡献通过原位广角X射线散射(WAXS),差示扫描量热法(DSC)和傅里叶变换红外光谱法确定。当在20°C min -1下从熔体冷却时,所有样品均显示α和β相晶体的混合物。然而,在4-米克星型星形共聚物样品中,β相的含量要比(PVDF)中的大得多。29 -N 3 2线性前体。因此,发现4-miktoarm星链拓扑结构诱导β相形成。随着样品以较低的速率冷却,PVDFβ相晶体的数量增加。对于在1°C min -1下结晶的样品,所有合成的(PVDF) 2 - b-(PEO) 2轻链星形共聚物的PVDF臂仅形成铁电/压电β相晶体。因此,这些材料在能量收集领域具有潜在的应用。
更新日期:2020-10-16
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