Local Mechanical Properties of Electrospun Fibers Correlate to Their Internal Nanostructure

Abstract

The properties of polymeric nanofibers can be tailored and enhanced by properly managing the structure of the polymer molecules at the nanoscale. Although electrospun polymer fibers are increasingly exploited in many technological applications, their internal nanostructure, determining their improved physical properties, is still poorly investigated and understood. Here, we unravel the internal structure of electrospun functional nanofibers made by prototype conjugated polymers. The unique features of near-field optical measurements are exploited to investigate the nanoscale spatial variation of the polymer density, evidencing the presence of a dense internal core embedded in a less dense polymeric shell. Interestingly, nanoscale mapping the fiber Young’s modulus demonstrates that the dense core is stiffer than the polymeric, less dense shell. These findings are rationalized by developing a theoretical model and simulations of the polymer molecular structural evolution during the electrospinning process. This model predicts that the stretching of the polymer network induces a contraction of the network toward the jet center with a local increase of the polymer density, as observed in the solid structure. The found complex internal structure opens an interesting perspective for improving and tailoring the molecular morphology and multifunctional electronic and optical properties of polymer fibers.

Cavitation-Induced Stiffness Reductions in Quantum Dot–Polymer Nanocomposites

“…The cavities form because of the nature of the chemical bonding at that interface, which is comparatively weak due to the nanoparticle surface chemistry and the processing conditions used in this study. 45 Direct visualization of such cavities around nanoparticles in structural composites via optical or transmission electron microscopy remains challenging, 3,8,10,[32][33][34] especially in the early stages of void formation. The LSM simulation provides a facile way to qualitatively model this effect, albeit in two dimensions, in partially phase-separated nanocomposites where the Young's modulus is lowered when a higher stiffness filler is added.…”

Tolnaftate-Loaded PolyacrylateElectrospun Nanofibers for an Impressive Regimen on Dermatophytosis

“…It is a lipophilic drug (partition coefficient log P > 5) with a large molecular weight of 307.41 g/mol and a poor aqueous solubility of <0.1 g/100 mL and is expected to show poor transport across the skin [6,7]. Recently, much research has been focused on fabricating three-dimensional nano fibers for applications in tissue engineering, catalysis, biosensors, skin regeneration, and wound healing by virtue of their extensive surface-to-volume ratio, peculiar morphology, sufficient mechanical strength, and plentiful porosity [8,9]. It is emphasized that the high surface area of nanofibers expedite proper gaseous exchange, charter fluid accumulation, or retention, of wound fluid, maintain moisture balance, and preserve aseptic conditions [10], which are eminently fascinating properties in the mitigation of infectious wound healing.…”

Water-soluble luminescent‐electrical‐magnetic trifunctional composite nanofibers prepared via electrospinning technique

“…Nowadays, investigation on the one-dimensional luminescent-electrical-magnetic multifunctional materials has become one of the hot spots in the field of materials science [2,3] . As far as we know, some studies of multifunctional composite nanofibers have been reported.…”