Local mechanical properties of electrospun fibers correlate to their internal nanostructure

Andrea Camposeo, Israel Greenfeld, Francesco Tantussi, Stefano Pagliara, Maria Moffa, Francesco Fuso, Maria Allegrini, Eyal Zussman, Dario Pisignano

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)5056-5062
Number of pages7
JournalNano Letters
Issue number11
StatePublished - 13 Nov 2013


  • Nanofibers
  • Young's modulus
  • conjugated polymers
  • near-field microscopy

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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