Morphological effects on dielectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) blends and multilayer films
Morphological effects on dielectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) blends and multilayer films
复制标题
DOI：
10.1016/j.polymer.2019.03.076
复制
发表时间：
2019-05
期刊：
影响因子：
4.6
通讯作者：
J. Tseng;K. Yin;Zhongbo Zhang;Matthew Mackey;E. Baer;Lei Zhu
中科院分区：
文献类型：
--
作者：
J. Tseng;K. Yin;Zhongbo Zhang;Matthew Mackey;E. Baer;Lei Zhu
与用于储能的铁电性聚偏氟乙烯（PVDF）的化学改性相比，聚合物共混物，无论是混相还是非混相，都是一种更容易抑制PVDF铁电性的方法。在这项研究中，我们探索了与聚（vdf -共六氟乙烯）[P(VDF-HFP)]的混相[即聚（甲基丙烯酸甲酯）或PMMA]和不混相（即聚碳酸酯或PC）共混物，以及PC/P（VDF-HFP）多层膜。对于混相PMMA/P（VDF-HFP）共混膜，PMMA的加入显著降低了P（VDF-HFP）的结晶度。当PMMA含量高达40 wt%时，拉伸后的PMMA/P（VDF-HFP）共混膜开始表现出线性介电行为，铁电性受到抑制。对于不混相的PC/P（VDF-HFP）共混膜，需要高达50 vol%的PC含量来抑制P（VDF-HFP）中的铁电性。当P（VDF-HFP）含量仅为30 vol%时，PC/P（VDF-HFP）多层膜开始出现线性滞回。更重要的是，PC/P（VDF-HFP）多层膜的击穿强度明显高于共混膜。这可以归因于垂直界面（相对于施加的电场），它作为有效的阻挡热电子从金属电极注入通过薄膜。通过本研究，与传统的混相和非混相共混材料相比，多层薄膜有望同时实现耐高温、高能量密度和低损耗的新一代薄膜电容器。
Compared with chemical modification of ferroelectric poly (vinylidene fluoride) (PVDF) for electric energy storage, polymer blends, whether miscible or immiscible, represent a much easier approach to suppress the ferroelectricity of PVDF. In this study, we explored both miscible [i.e., poly (methyl methacrylate) or PMMA] and immiscible (i.e., polycarbonate or PC) blends with poly (VDF-co-hexafluoroethylene) [P(VDF-HFP)], as well as the PC/P(VDF-HFP) multilayer films. For miscible PMMA/P(VDF-HFP) blend films, the addition of PMMA significantly decreased the crystallinity of P(VDF-HFP). At a high PMMA content of ca. 40 wt%, the stretched PMMA/P(VDF-HFP) blend films started to exhibit the linear dielectric behavior with suppressed ferroelectricity. For the immiscible PC/P(VDF-HFP) blend films, a high PC content of ∼50 vol% was required to suppress the ferroelectricity in P(VDF-HFP). Instead, the PC/P(VDF-HFP) multilayer films started to show linear hysteresis loops when the content of P(VDF-HFP) was only 30 vol%. More importantly, the PC/P(VDF-HFP) multilayer films exhibited significantly higher breakdown strength than the blend films. This could be attributed to the perpendicular interfaces (with respect to the applied electric field), which serve as effective blocks for hot electrons injected from the metal electrodes to pass through the film. From this study, compared to conventional miscible and immiscible blends, multilayer films are promising for next generation film capacitors, aiming to achieve high temperature tolerance, high energy density, and low loss simultaneously.