Polymer Solution or Melt:
The polymer is first dissolved in a solvent or melted to create a solution or melt of a specific concentration and viscosity.
The polymer solution needs to be carefully prepared to ensure it has the right properties to be electrospun (e.g., viscosity, surface tension, and conductivity).
Application of Electric Field:
A high voltage is applied between the needle (or spinneret) and the collector.
The positive or negative high voltage causes the polymer solution at the tip of the needle to become charged.
Formation of Taylor Cone:
As the voltage is applied, the solution at the needle tip deforms into a cone-shaped structure known as the Taylor cone. This is the point where the electrostatic forces overcome the surface tension of the solution.
The electric field stretches and elongates the polymer solution at the tip of the cone.
Jet Formation:
At the apex of the Taylor cone, a thin jet of the polymer solution is ejected.
This jet accelerates toward the collector due to the electric field.
Stretching and Thinning of the Jet:
As the jet moves toward the collector, it undergoes stretching due to the electric field, causing the polymer solution to thin into long, ultrafine fibers. This stretching can be enhanced by the surface tension of the solution and the electric field strength.
During this process, the solvent in the polymer solution evaporates (if using a solution), and the polymer solidifies into fine fibers.
Fiber Deposition on Collector:
The electrospun fibers are collected on the grounded or oppositely charged collector, forming a nonwoven mat or membrane of nanofibers.
The collector may be a flat plate, rotating drum, or mesh, depending on the desired fiber arrangement and alignment.
If the collector is rotating, the fibers can align in specific patterns due to the mechanical forces during collection.
Fiber Characteristics:
The electrospun fibers produced by this method typically have diameters ranging from nanometers to micrometers, with a high surface area-to-volume ratio.
The properties of the fibers (e.g., diameter, porosity, alignment, and morphology) can be controlled by adjusting the parameters such as polymer concentration, voltage, flow rate, and distance between the needle and the collector.