Dielectric and energy harvesting properties of functionalized composite nanofibers consisting of Boc-Phe-Leu self-assembled dipeptide inclusions in biocompatible polymeric matrices

Abstract Hybrid bionanomaterials were produced through electrospinning, incorporating the dipeptide Boc- l -phenylalanyl- l -leucine into nanofibers of biocompatible polymers. Scanning electron microscopy confirmed the uniformity of the nanofibers, with diameters ranging from 0.56 to 1.61 µm. The dielectric properties of the nanofibers were characterized using impedance spectroscopy, assessing temperature and frequency dependencies. Notably, the composite micro/nanofibers exhibited semiconducting dielectric behavior with bandgap energies of 4–5 eV, and their analysis revealed increased dielectric constant with temperature due to enhanced charge mobility. The successful incorporation of the dipeptide was verified by Maxwell–Wagner interfacial polarization, and the Havriliak–Negami model disclosed insights into electric permittivity. Furthermore, the fibers demonstrated pyroelectric and piezoelectric responses, with Boc-Phe-Leu@PLLA nanofibers having the highest piezoelectric coefficient of 85 pC/N. These findings highlight the influence of dipeptide nanostructures on dielectric, pyroelectric, and piezoelectric properties, suggesting the potential of polymeric micro/nanofibers as efficient piezoelectric energy generators for portable and wearable devices. Graphical Abstract