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 (Poly-L-lactic acid, Polycaprolactone, and Poly(methyl methacrylate). Scanning electron microscopy confirmed the uniformity of the nanofibers, with diameters ranging from 0.56 to 1.61 mm. The dielectric properties of the nanofibers were characterized using impedance spectroscopy, assessing temperature and frequency dependencies. Remarkable alterations in nanofiber behavior were observed due to the presence of embedded dipeptides. This study enhances our understanding of the dielectric performance of composite polymeric nanofibers and highlights the influence of dipeptide nanostructures on their dielectric, pyroelectric, and piezoelectric properties. Notably, the composite micro/nanofibers, including Boc-Phe-Leu@PLLA, exhibited semiconducting dielectric behavior with bandgap energies of 4-5 eV. The analysis revealed an increased dielectric constant with temperature, attributed to enhanced charge mobility. Maxwell-Wagner interfacial polarization confirmed the successful incorporation of the dipeptide in the fibers. The Havriliak-Negami model provided insights into the electric permittivity and revealed the contribution of polaron and ionic conduction, dependent on the polymer matrix. The fibers also demonstrated pyroelectric and piezoelectric responses, with Boc-Phe-Leu@PLLA nanofibers exhibiting the highest piezoelectric coefficient of 85 pC/N. These findings validate the potential of polymeric micro/nanofibers as piezoelectric energy generators for portable and wearable devices.