# Diversified Morphology of Electrospun Fibers through Self-Assembly of the Strings in the Jet Developed by Flow-Induced Phase Separation

## TL;DR

This paper explains how electrospun fibers can form various shapes like ribbons and beads due to phase separation in the jet.

## Contribution

The study reveals flow-induced phase separation as a unifying mechanism for diverse electrospun fiber morphologies.

## Key findings

- Phase separation in the jet leads to hierarchical string structures in electrospun fibers.
- Lateral association of these strings creates different fiber features like beads and barbs.
- The mechanism applies to multiple polymers, unifying the understanding of fiber morphology.

## Abstract

Solution electrospinning produces not only round fibers
but also
many unexpected features, e.g., ribbons, nets, and fibers with beads,
barbs, or branches along the fiber length. These diversified features
are observed in the electrospun fibers of poly­(vinyl alcohol), Nylon-6,
poly­(N-isopropylacrylamide), ultrahigh-molecular-weight
polystyrene, and ultrahigh-molecular-weight polyethylene in this study.
All these unique features could be realized through our recent discoveries
that flow-induced phase separation occurs in the jet to develop polymer-rich
phases of hierarchical string structures with various diameters. Subsequently,
lateral association (or fasciation) of the hierarchical strings ensues
and creates assembled strings of different kinds, which are split
from the phase-separated jet and evolve into as-spun features after
solvent evaporation. Our results indicate that flow-induced phase
separation in jets cannot be overlooked and is likely to unify the
formation mechanism of all diversified morphologies of electrospun
products.