Houssat Mohammed, Villeneuve-Faure Christina, Lahoud Dignat Nadine, Cambronne Jean-Pascal
LAPLACE, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
Nanotechnology. 2021 Jul 28;32(42). doi: 10.1088/1361-6528/ac13ea.
Polymer nanocomposites (pNC) have attracted wide interests in electrical insulation applications. Compared to neat matrices or microcomposites, pNC provide significant improvements in combined electrical, mechanical and thermal properties. In the understanding of the reasons behind these improvements, a major role was attributed to the interphase, the interaction zone between the nanoparticles (NP) and the matrix. Because of their nanoscale dimensions, the interphase properties are mostly theoretically described but rarely experimentally characterized. The aim of this study is to propose a nanoscale measurement protocol in order to probe mechanical (Young modulus) and electrical (dielectric permittivity) interphase features using, respectively, the peak force quantitative nanomechanical (PF-QNM) and the electrostatic force microscopy (EFM) modes of the atomic force microscopy. Measurements are performed on polyimide/silicon nitride (SiN) nanocomposite and the effect of a silane coupling agent treatment of SiNNP is considered. In order to accurately probe mechanical properties in PF-QNM mode, the impacting parameters such as the applied force, the deformation and the topography are taken into account. The interphase region has shown a higher elastic modulus compared to the matrix and a higher width () value for treated NP. From EFM measurements combined to a finite element model feeded with thevalues obtained from PF-QNM, the interphase permittivity is determined. The corresponding values are lower than the matrix one and similar for untreated and treated NP. This is in total agreement with its higher elastic modulus and implies that the interphase is a region around the NP where the polymer chains present a better organization and thus, a restricted mobility.
聚合物纳米复合材料（pNC）在电气绝缘应用中引起了广泛关注。与纯基体或微复合材料相比，pNC在电、机械和热性能方面有显著提升。在理解这些性能提升背后的原因时，一个主要作用被归因于界面相，即纳米粒子（NP）与基体之间的相互作用区域。由于其纳米尺度的尺寸，界面相的性质大多是从理论上描述的，但很少通过实验进行表征。本研究的目的是提出一种纳米尺度的测量方案，以便分别使用原子力显微镜的峰值力定量纳米力学（PF-QNM）和静电力显微镜（EFM）模式来探测机械（杨氏模量）和电气（介电常数）界面相特征。对聚酰亚胺/氮化硅（SiN）纳米复合材料进行测量，并考虑了硅烷偶联剂处理SiN纳米粒子的效果。为了在PF-QNM模式下准确探测机械性能，考虑了诸如施加力、变形和形貌等影响参数。与基体相比，界面相区域显示出更高的弹性模量，并且处理后的纳米粒子具有更高的宽度（）值。通过将EFM测量结果与由PF-QNM获得的值输入的有限元模型相结合，确定了界面相的介电常数。相应的值低于基体的值，并且未处理和处理后的纳米粒子相似。这与其较高的弹性模量完全一致，意味着界面相是纳米粒子周围的一个区域，其中聚合物链呈现出更好的排列，因此具有受限的流动性。
