Electrospun Microstructured Biopolymer Fibers Containing the Self-Assembled Boc–Phe–Ile Dipeptide: Dielectric and Energy Harvesting Properties

Abstract

Hybrid biomaterials were engineered using the electrospinning technique, incorporating the dipeptide Boc–L-phenylalanyl–L-isoleucine into microfibers composed of biocompatible polymers. The examination by scanning electron microscopy affirmed the morphology of the microfibers, exhibiting diameters ranging between 0.9 and 1.8 µm. The dipeptide self-assembles into spheres with a hydrodynamic size between 0.18 and 1.26 µm. The dielectric properties of these microfibers were characterized through impedance spectroscopy where variations in both temperature and frequency were systematically studied. The investigation revealed a noteworthy rise in the dielectric constant and AC electric conductivity with increasing temperature, attributable to augmented charge mobility within the material. The successful integration of the dipeptide was substantiated through the observation of Maxwell–Wagner interfacial polarization, affirming the uniform dispersion within the microfibers. In-depth insights into electric permittivity and activation energies were garnered using the Havriliak–Negami model and the AC conductivity behavior. Very importantly, these engineered fibers exhibited pronounced pyroelectric and piezoelectric responses, with Boc–Phe–Ile@PLLA microfibers standing out with the highest piezoelectric coefficient, calculated to be 56 pC/N. These discoveries help us understand how dipeptide nanostructures embedded into electrospun nano/microfibers can greatly affect their pyroelectric and piezoelectric properties. They also point out that polymer fibers could be used as highly efficient piezoelectric energy harvesters, with promising applications in portable and wearable devices.

Electrospun 3D Curly Electret Nanofiber Air Filters for Particulate Pollutants

“…Due to the different charge transport capabilities of PVDF and TiO 2 NPs, a charge barrier is generated at the interface, making it difficult for the charges to transfer at the interface. Accumulate to form interface charges [39], it can be seen from the XRD pattern that the addition of TiO 2 NPs also affects the crystal phase formation of PVDF fiber, which may also be another reason for its better performance in terms of electret effect. With the increase of TiO 2 content, the electret effect decreases, which may be due to the formation of charge channels due to the aggregation of TiO 2 , resulting in uneven charge distribution and decreased charge storage capacity, but it is still significantly higher than that of H-P a fibrous membrane without adding TiO 2 .…”