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首页> 外文期刊>Crystal growth & design >Contrasting Effects of Graphene Oxide and Poly(ethylenimine) on the Polymorphism in Poly(vinylidene fluoride)
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Contrasting Effects of Graphene Oxide and Poly(ethylenimine) on the Polymorphism in Poly(vinylidene fluoride)

机译：氧化石墨烯和聚乙烯亚胺对聚偏二氟乙烯多态性的影响

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摘要

The nature of interaction between a heteronucleating agent (graphene oxide, GO) and a strongly polar macromolecule (poly(ethylenimine), PEI) with poly(vinylidene fluoride) (PVDF) influencing the crystalline structure and morphology has been systematically investigated in this work. PEI interacts with PVDF via ion-dipole interaction, which helps in lowering the free energy barrier for nucleation thereby promoting faster crystallization. In contrast, besides interacting with PVDF, GO also promotes heteronucleation in PVDF. We observed that both GO and PEI have very different effects on the overall crystalline morphology of PVDF. For instance, the neat PVDF showed a mixture of both alpha and beta phases when cooled from the melt. However, incorporation of 0.1 wt % GO resulted in phase transformation from the stable alpha-phase to polar beta-polymorph in PVDF. In contrast, PEI, which also resulted in faster crystallization in PVDF predominantly, resulted in the stable alpha- phase. Various techniques like Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry were employed to confirm the phase transformations in PVDF. PEI was further grafted onto GO nanosheets to understand the combined effects of both GO and PEI on the polymorphism in PVDF. The PVDF/PEI-GO composite showed a mixture of phases, predominantly rich in a. These phenomenal effects were further analyzed and corroborated with the specific interaction between GO and PEI with PVDF using X-ray photon scattering (XPS) and NMR. In addition, the dielectric permittivity increased significantly in the presence of GO and PEI in the composites. For instance, PVDF/PEI-GO showed the highest permittivity of 39 at 100 Hz.
机译：在这项工作中，已经系统地研究了杂成核剂（氧化石墨烯，GO）与强极性大分子（聚（乙烯亚胺），PEI）与聚偏二氟乙烯（PVDF）之间相互作用的性质，该相互作用影响晶体的结构和形态。 PEI通过离子-偶极相互作用与PVDF相互作用，这有助于降低成核的自由能垒，从而促进更快的结晶。相反，除了与PVDF相互作用外，GO还促进了PVDF中的异核。我们观察到GO和PEI对PVDF的整体晶体形态都有很大不同的影响。例如，当从熔体冷却时，纯净的PVDF显示出α和β相的混合物。然而，在PVDF中掺入0.1重量％的GO导致从稳定的α相到极性β-多晶型物的相变。相反，PEI主要导致PVDF结晶更快，从而产生稳定的α相。诸如傅里叶变换红外光谱，X射线衍射和差示扫描量热法等各种技术被用于确认PVDF中的相变。将PEI进一步嫁接到GO纳米片上，以了解GO和PEI两者对PVDF中多态性的综合影响。 PVDF / PEI-GO复合材料显示出相相的混合物，主要是富含α。使用X射线光子散射（XPS）和NMR，进一步分析了这些现象，并证实了GO和PEI与PVDF之间的特定相互作用。另外，在复合物中存在GO和PEI的情况下，介电常数显着增加。例如，PVDF / PEI-GO在100 Hz时显示出最高的介电常数39。

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