Self-Poled PVDF Infiltrated Nylon 11 Aerogels with Oriented Crystals for High-Performance Piezoelectric Energy Harvesters and Self-Powered Acoustic Sensors

Abstract

Efficient piezoelectric polymers with enhanced electromechanical conversion gain significant attention for energy harvesting and sensing applications. Among them, poly(vinylidene fluoride) (PVDF) and odd-nylons stand out due to their high piezoelectric coefficients and thermal stability. However, achieving a piezoelectric phase with a preferred crystal orientation for optimal performance remains challenging, particularly under mild processing conditions. In this study, a vacuum-assisted infiltration technique is introduced to fabricate PVDF-infiltrated nylon-11 (PVDFIPA11) aerogels with oriented polymer crystallites. Anisotropic nylon-11 aerogels, featuring aligned polymer crystals, serve as templates for PVDF infiltration under vacuum. This process facilitates the formation of highly oriented β phase PVDF crystals alongside γ phase nylon-11 crystals, yielding a fully self-poled system without the need for external poling. A piezoelectric nanogenerator (PENG) based on the PVDFIPA11 aerogel exhibits a high output voltage (peak-to-peak) of ≈45 Vpp and a peak power density of 2.2 Wm⁻3 significantly outperforming pristine PVDF and nylon-11 aerogels. Additionally, the PVDFIPA11 aerogel PENG is demonstrated as a self-powered acoustic sensor, effectively distinguishing sound signals at varying pressure levels. This work provides a scalable and practical strategy for developing self-poled piezoelectric polymer aerogels, paving the way for next-generation energy-harvesting devices and sensors.