Electrospun Polylactide—Poly(ε-Caprolactone) Fibers: Structure Characterization and Segmental Dynamic Response

Electrospun ultrathin fibers based on binary compositions of polylactide (PLA) and poly(ε-caprolactone) (PCL) with the various content from the polymer ratio from 0/100 to 100/0 have been explored. Combining thermal (DSC) and spectropy (ESR) techniques, the effect of biopolymer content on the characteristics of the crystal structure of PLA and PCL and the rotative diffusion of the stable TEMPO radical in the intercrystallite areas of PLA/PCL compositions was shown. It was revealed that after PLA and PCL blending, significant changes in the degree of crystallinity of PLA, PCL segment mobility, sorption of the Tempo probe, as well as its activation energy of rotation in the intercrystalline areas of PLA/PCL fibers, were evaluated. The characteristic region of biopolymers' composition from 50/50 to 30/70% PLA/PCL blend ratio was found, where the inversion transition of PLA from dispersive medium to dispersive phase where an inversion transition is assumed when the continuous medium of the PLA transforms into a discrete phase. The performed studies made it possible, firstly, to carry out a detailed study of the effect of the system component ratio on the structural and dynamic characteristics of the PLA/PCL film material at the molecular level.