Modeling-based mechanistic insights into the role of barium titanate shape and microstructural defects in coupled-field responses of piezoelectric nanocomposites

Abstract

Barium titanate (BT) nanofillers play a crucial role in polymer nanocomposites due to their remarkable intrinsic properties, which markedly improve the effectiveness of energy conversion. However, the synthesis of BT nanofillers in varied structural profiles, such as nanowires, nanoplatelets, and nanoparticles, along with their dispersion within the polymer matrix, exerts a substantial impact on the overall performance of the nano-composite. Non-uniform nanofiller dispersion is inherently tied to the development of microstructural defects, including poor compatibility between phases, the formation of voids, and nanofiller agglomeration. This study investigates the influence of BT nanofiller shape and microstructural defects on the effective properties of BT/ polydimethylsiloxane (PDMS) piezoelectric nanocomposites. Based on a micromechanics-based finite element framework, representative volume elements (RVEs) of the nanocomposite are generated using a morphology-centric computational simulation, and their Young's moduli, piezoelectric coefficients, and thermal expansion coefficients are subsequently predicted. The results indicate that establishing robust interphase regions, driven by enhanced interfacial compatibility, has a direct impact on elevating system functionality. Additionally, the adverse effects of void defects and nanofiller agglomeration on the effective properties are alleviated through void minimization and agglomerate breakdown.