Université Lille, Sciences et Technologies, CNRS, Unité Matériaux Et Transformations (UMET) , F-59000 Lille , France.
Université Artois, CNRS, Centrale Lille, ENSCL, Université Lille, UMR 8181, Unité de Catalyse et Chimie du Solide (UCCS) , F-62300 Lens , France.
ACS Appl Mater Interfaces. 2018 Apr 18;10(15):13092-13099. doi: 10.1021/acsami.8b02172. Epub 2018 Apr 5.
The impact of carbon nanotube (CNT) incorporation into semicrystalline poly(vinylidene fluoride), PVDF, was investigated at both the macro and nanoscales. A special effort was devoted to probe the local morphology and the mechanical, ferroelectric, piezoelectric, and electrical conductivity response by means of atomic force microscopy. Incorporation of CNTs mainly induces the development of the polar γ-phase, and as a consequence, the coexistence of the γ-phase with the most stable nonpolar α-phase is observed. A maximum γ-phase content is reached at 0.7 wt % CNT loading. The spherulitic morphology of the PVDF α-phase is assessed, in conjunction with the lack of any ferroelectric response, while the presence of the polar γ-phase is confirmed, owing to clear piezoresponse signals. Local piezoelectric measurements on γ-phase domains yield a maximum effective coefficient | d| ≈ 13 pm/V, thus underlining the potential for applications of such functional PVDF-based nanocomposites in advanced piezoelectric devices. An increase in macroscopic conductivity with CNT content is observed, with a percolation threshold achieved for a composition close to 0.7 wt %. Nanoscale investigation of the electrical conductivity confirms the presence of some infinite CNT cluster homogeneously distributed over the surface. The macroscopic viscoelastic behavior of the composite reflects the reinforcing effect of CNTs, while the nanomechanical characterization yields a local contact modulus of the γ-phase domains larger than that of its α-phase counterpart, in agreement with the fact that the CNTs act as γ-phase promoters and subsequently reinforce the γ-domains.
将碳纳米管（CNT）掺入半晶态聚偏二氟乙烯（PVDF）中，从宏观和微观尺度上进行了研究。通过原子力显微镜，特别致力于探测局部形态以及机械、铁电、压电和电导率响应。CNT 的掺入主要诱导了极性 γ 相的发展，因此观察到了 γ 相与最稳定的非极性 α 相的共存。在 0.7wt%CNT 负载下达到最大 γ 相含量。评估了 PVDF α 相的球晶形态，同时缺乏任何铁电响应，而由于存在明显的压电阻抗信号，确认了极性 γ 相的存在。对 γ 相畴进行局部压电测量，得到最大有效系数 |d|≈13 pm/V，从而强调了基于此类功能性 PVDF 的纳米复合材料在先进压电器件中应用的潜力。随着 CNT 含量的增加，观察到宏观电导率的增加，在接近 0.7wt%的组成下达到渗流阈值。电导率的纳米尺度研究证实了一些无限 CNT 簇均匀分布在表面上。复合材料的宏观粘弹性行为反映了 CNT 的增强效果，而纳米力学特性得出 γ 相畴的局部接触模量大于其 α 相对应物，这与 CNT 作为 γ 相促进剂并随后增强 γ 畴的事实一致。
