Production of composite nanomaterials
Electrospinning is a comparatively simple, effective and universal fabrication method for producing nanofibers with diameters ranging from 50nm to several micrometers using polymer solution melts. Normally electrospinning devices enable the production of electrospun nanofibers from only one material. Further enhancements to the electrospinning device resulted in the production of nanofibrous with different types of polymers improving their material properties.
A new desktop laboratory apparatus has been developed for nanofiber production from the solutions of synthetic and natural polymers. The 4SPIN® device features five types of emitters for composite materials that can be used for simultaneous electrospinning of two or three different polymer types on the same collector. A needle jet emitter is the simplest method to be used. It forms a high gradient electrostatic field around the drop of the polymer solution leading to very high spinnability.
Figure 1. A modified electrospinning set-up with a rotating drum collector was applied. The revolutions of the drum were set to 500 rpm.
Another technique is needleless electrospinning, a process capable of scaling up the nanofibrous material production. To obtain homogeneously mixed nanofibrous layers, nanofiberscan bed directly collected on a rotating drum. A coaxial single needle jet is another advanced type of the 4SPIN® emitter. By using the coaxial electrospinning method, one can produce hollow fibers and even core materials that will not form fibers via electrospinning.
Figure 2. Absorption spectra obtained from nanofibrous layers separately from PVA with Brilliant Blue (BB), PVA with Erythrosin (Er) and their composite material fabricated on the drum collector (A, B, C).
Used Methods and Materials
Electrospinning of all nanomaterials was done with the new types of emitters of the 4SPIN® technology.
The following six polymers were used to prepare composite nanomaterials:
- polyethylene oxide (PEO)
- hyaluronic acid/polyethylene oxide blends (HA/PEO)
- polyvinylalcohol (PVA)
- polycaprolactone (PCL)
- polyurethane (PU)
- polyacrylonitrile (PAN).
Electrospinning or electrospraying methods were used to prepare composite nanostructures based on the concentration of the polymer solution used. A rotating drum collector was used to collect the nanofibers. The jets must be behind each other on the plane perpendicular to the axis of rotation of the drum collector. By determining the absorption spectra of its individual components, the homogeneity of polymer distribution in a nanofibrous layer is verified. By adding the brilliant blue dye of absorbance 570nm and erythrosine 530nm the two PVA solutions were prepared.
Figure 3. Nanofibrous materials from PVA with the Brilliant Blue dye and with Erythrosin deposited on the static continual (on the left) and rotating drum collector (on the right).
Confocal Raman spectroscopy was used to non-invasively determined chemical composition of the resulting material. Confocal Raman arrangement enables detection of fine elastically scattered radiation from a selected area on the surface of the sample.
Spectral differences can indicate spatial distribution of the individual components of composite nanofibrous layers.
Figure 4. Raman spectra of PCL and PEO representing the main differences between the polymers.
Figure 5. 2D maps of the fingerprint region and CH groups region of a PEO and PCL composite nanofibrous material for the sample area of (5 • 5)cm2. Theredareas are dominated by PCL, the blue areas pertain to PEO. The green colour represents the area where the sample was the same as the average spectrum from the measured spectra of polymers.
What we find our
Composite nanofibrous materials composed of two or three different types of polymers were prepared using new types of emitters. Various morphologies were also achieved in the resulting materials. The homogeneity and distribution of individual components were analysed with a spectrophotometer and examined using Raman spectroscopy.
Thanks to the implemented methods and the new types of emitters the 4SPIN® device can produce composite and hybrid nanostructures which improve the material’s final quality and thus significantly helps accelerate research progress in the field of material application.