Gupta Praveen, Ruzicka Eric, Benicewicz Brian C, Sundararaman Ravishankar, Schadler Linda S
College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont05405, United States.
Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York12180, United States.
ACS Appl Electron Mater. 2023 Jan 19;5(2):794-802. doi: 10.1021/acsaelm.2c01331. eCollection 2023 Feb 28.
Knowing the dielectric properties of the interfacial region in polymer nanocomposites is critical to predicting and controlling dielectric properties. They are, however, difficult to characterize due to their nanoscale dimensions. Electrostatic force microscopy (EFM) provides a pathway to local dielectric property measurements, but extracting local dielectric permittivity in complex interphase geometries from EFM measurements remains a challenge. This paper demonstrates a combined EFM and machine learning (ML) approach to measuring interfacial permittivity in 50 nm silica particles in a PMMA matrix. We show that ML models trained to finite-element simulations of the electric field profile between the EFM tip and nanocomposite surface can accurately determine the interface permittivity of functionalized nanoparticles. It was found that for the particles with a polyaniline brush layer, the interfacial region was detectable (extrinsic interface). For bare silica particles, the intrinsic interface was detectable only in terms of having a slightly higher or lower permittivity. This approach fully accounts for the complex interplay of filler, matrix, and interface permittivity on the force gradients measured in EFM that are missed by previous semianalytic approaches, providing a pathway to quantify and design nanoscale interface dielectric properties in nanodielectric materials.
了解聚合物纳米复合材料界面区域的介电特性对于预测和控制介电性能至关重要。然而，由于其纳米级尺寸，它们很难被表征。静电力显微镜（EFM）为局部介电性能测量提供了一条途径，但从EFM测量中提取复杂相间几何结构中的局部介电常数仍然是一个挑战。本文展示了一种结合EFM和机器学习（ML）的方法来测量PMMA基体中50 nm二氧化硅颗粒的界面介电常数。我们表明，通过对EFM尖端与纳米复合材料表面之间电场分布的有限元模拟训练的ML模型，可以准确确定功能化纳米颗粒的界面介电常数。研究发现，对于带有聚苯胺刷层的颗粒，界面区域是可检测的（外在界面）。对于裸二氧化硅颗粒，仅在介电常数略高或略低的情况下才能检测到内在界面。这种方法充分考虑了填料、基体和界面介电常数在EFM中测量的力梯度上的复杂相互作用，而之前的半解析方法忽略了这一点，为量化和设计纳米介电材料中的纳米级界面介电性能提供了一条途径。
