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Nanoconfinement-Induced β-Phase Formation Inside Poly(vinylidene fluoride)-Based Block Copolymers
ACS Macro Letters ( IF 5.8 ) Pub Date : 2018-07-02 00:00:00 , DOI: 10.1021/acsmacrolett.8b00418
Niels L. Meereboer 1 , Ivan Terzić 1 , Sarah Saidi 2 , Daniel Hermida Merino 3 , Katja Loos 1
Affiliation  

The electroactive properties of poly(vinylidene fluoride) (PVDF) are a direct consequence of its crystalline phases. Although poorly understood, nanostructuring PVDF in confined geometries can drastically change its crystallization behavior. Therefore, we synthesized a variety of PVDF-based triblock copolymers to gain a better understanding of the melt crystallization and explore how crystallization is affected by the morphology and chemical nature of the amorphous block. Differential scanning calorimetry, small-/wide-angle X-ray scattering, and transmission electron microscopy gave us excellent insights into the morphology and the corresponding crystalline phases. We find that crystallization of PVDF inside spherical nanodomains occurs via a homogeneous nucleation mechanism leading to a large undercooling and the formation of the thermodynamically favorable ferroelectric β-phase. On the contrary, when confined crystallization occurs inside a lamellar morphology, or in the case of breakout crystallization, a heterogeneous nucleation process leads to the formation of the nonferroelectric α-phase. Furthermore, favorable melt interactions between both blocks induce crystallization into the polar γ-phase at moderate cooling rates.

中文翻译:

纳米约束诱导的聚偏二氟乙烯基嵌段共聚物中β相的形成

聚偏二氟乙烯(PVDF)的电活性是其结晶相的直接结果。尽管知之甚少,但在有限的几何形状中纳米结构化的PVDF可以极大地改变其结晶行为。因此,我们合成了多种基于PVDF的三嵌段共聚物,以更好地理解熔体结晶,并探索了结晶如何受到非晶态嵌段的形态和化学性质的影响。差示扫描量热法,小/广角X射线散射和透射电子显微镜使我们对形态和相应的结晶相有了很好的了解。我们发现球形纳米域内部的PVDF结晶是通过均相成核机制发生的,从而导致大量的过冷和热力学上有利的铁电β相的形成。相反,当在层状形态内部发生有限的结晶时,或者在破裂结晶的情况下,异相成核过程导致形成非铁电α相。此外,两个嵌段之间有利的熔体相互作用在中等冷却速率下诱导结晶成极性γ相。
更新日期:2018-07-02
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