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

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 V_pp 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.