Mapping the Space Charge at Nanoscale in Dielectric Polymer Nanocomposites

Abstract

Heterogeneous dielectric materials such as dielectric polymer nanocomposites have attracted extensive attention because of their exceptional insulating and dielectric performance, which originates from the unique space charge dynamics associated with the various interfacial regions. However, the space charge distribution and transport in polymer nanocomposites remain elusive due to the lack of analytical methods that can precisely probe the charge profile at the nanoscale resolution. Although a few studies have explored the possibility of using scanning probe techniques for characterizing the local charge distribution, the interference from induced electrical polarization of the material has been unfortunately ignored, leading to inaccurate results. In this contribution, we report an open-loop Kelvin probe force microscopy (KPFM) method with nanoscale resolution for the direct detection of the space charge profile in dielectric polymer nanocomposites. Unlike the conventional studies where a vertical direct current (DC) voltage is applied on the sample through the probe to evoke the charge injection and transport in dielectric polymer nanocomposites, the present method is established based on a delicate electrode configuration where a lateral electric field is allowed to be applied on the sample during the KPFM test. This special testing configuration enables real-time charge injection and transport without inducing the electrical polarization of material along the vertical direction, which gives rise to clean mapping of space charges and reveals the interfacial charge trapping in polymer nanocomposites. This work provides a robust and reliable method for studying the sophisticated charge transport properties associated with the various interfacial regions in heterogeneous dielectric materials.

Tailoring Interfacial Properties in Polymer–Silica Nanocomposites via Surface Modification: An Atomistic Simulation Study

“…As a result, adding a small amount of nanofillers into polymer can lead to a dramatic improvement in mechanical, thermal, electrical, and optical properties, while maintaining the low mass density and good processability inherent to the polymer. 2,3,6,8 In addition, the incorporation of nanoparticles can also introduce new functionalities (e.g., conductivity 3 ) that are absent in the pristine polymer matrix, which further extends the utility of the constituted nanocomposites. Thus, designing PNCs offers a versatile strategy for preparing highperformance and cost-effective materials, which find broad applications in materials, energy storage, and biomedical fields.…”

“…Polymer nanocomposites (PNCs), formed by dispersing nanoparticles in a polymer matrix, have drawn substantial attention from both industry and academia in past decades. − Compared to traditional fillers, nanofillers, reducing the object size, significantly increase the interfacial area between fillers and polymer that efficiently modifies the matrix properties. As a result, adding a small amount of nanofillers into polymer can lead to a dramatic improvement in mechanical, thermal, electrical, and optical properties, while maintaining the low mass density and good processability inherent to the polymer. ,,, In addition, the incorporation of nanoparticles can also introduce new functionalities (e.g., conductivity) that are absent in the pristine polymer matrix, which further extends the utility of the constituted nanocomposites. Thus, designing PNCs offers a versatile strategy for preparing high-performance and cost-effective materials, which find broad applications in materials, energy storage, and biomedical fields. ,,, However, due to the complex nature of PNCs as multicomponent systems, the corresponding control parameter space is large.…”

Enhancing Dielectric Strength of Epoxy Polymers by Constructing Interface Charge Traps

“…Then, Takada proposed a multiregion structure model of nanocomposite dielectrics . According to this model, nanoparticles introduce trap sites at the polymer matrix–nanoparticle interface, − which can hinder the movement of high-energy electrons and the development of breakdown paths, as well as increase the dielectric strength. For instance, Li et al reported the charge mobility and dielectric strength of a nano-Al 2 O 3 -filled polymer, which was capable of dispersing the applied electric field throughout the polymer matrix and preventing the propagation of breakdown channels, thereby resulting in the highest dielectric strength and lowest leakage current in polymer nanocomposites.…”

Temperature Influence on PI/Si3N4 Nanocomposite Dielectric Properties: A Multiscale Approach

“…However, the interphase properties remain challenging to characterize Polymers 2021, 13,1936 2 of 13 and their impact on NC ones are, consequently, poorly understood. To characterize interphase properties at the local scale, techniques derived from the Atomic Force Microscopy (AFM) were used: the Peak Force Quantitative NanoMechanical (PF-QNM) mode for the interphase mechanical properties and dimension determination [25,26], the Electrostatic Force Microscopy (EFM) mode for the dielectric permittivity [27][28][29], and the Kelvin Probe Force Microscopy (KPFM) for space charge measurements [30,31]. All of these existing studies only provide an interphase characterization at room temperature and a partial description of dielectric properties as some assumptions are requested for their entire determination.…”