Nanoconfinement-Induced beta-Phase Formation Inside Poly(vinylidene fluoride)-Based Block Copolymers

作者：Meereboer Niels L; Terzic Ivan; Saidi Sarah; Merino Daniel Hermida; Loos Katja^*

来源：ACS Macro Letters, 2018, 7(7): 863-867.

DOI：10.1021/acsmacrolett.8b00418

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 beta-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 alpha-phase. Furthermore, favorable melt interactions between both blocks induce crystallization into the polar gamma-phase at moderate cooling rates.

• 出版日期2018-7