Structural, Thermal, Morphological, and Optical Characterization of Electrospun AlTiO/PCL-PEG Nanofiber Composites

Abstract

In this study, Al-doped TiO2 (AlTiO2) nanoparticles were synthesized using a hydrothermal method and incorporated into poly(epsilon-caprolactone)/polyethylene glycol (PCL-PEG)-based nanofibers produced via the electrospinning method at different concentrations (15, 20, and 40%). The structural, morphological, thermal, surface, and optical properties of the resulting composite nanofibers were comprehensively investigated. X-ray diffraction (XRD) analyses revealed that the synthesized AlTiO2 nanoparticles predominantly exhibited a rutile phase crystal structure. Fourier transform infrared spectroscopy (FTIR) results revealed that the characteristic functional groups of the PCL-PEG matrix were preserved despite the addition of AlTiO2, and that the nanoparticles were physically dispersed within the polymer structure. Scanning electron microscopy (SEM) images showed that the AlTiO2 addition significantly affected fiber morphology and fiber diameter distribution; it was determined that the most homogeneous and defect-free fiber structure was obtained in the composite containing 20% AlTiO2. Differential scanning calorimetry (DSC) analyses showed that the addition of AlTiO2 did not significantly alter the melting temperature but increased the melting enthalpy, thereby enhancing the degree of crystallinity of the composites. Thermogravimetric analysis (TGA) results revealed that the AlTiO2 addition improved thermal stability and increased the residual mass at high temperatures. Atomic force microscopy (AFM) analyses showed that the addition of nanoparticles effectively altered the surface topography and surface roughness. UV-Vis spectroscopy and Tauc analyses revealed that the optical bandgap, which was determined to be 4.16 eV in pure PCL-PEG nanofibers, decreased to 2.91 eV with increasing AlTiO2 content. The results indicate that AlTiO2 doping significantly enhances the structural, thermal, and optical performance of PCL-PEG nanofibers produced via the electrospinning method, and that these composites are promising candidates for biomedical, photocatalytic, and advanced functional material applications.