Solvents for electrospinning

Bosworth, L.A., Downes, S., 2012. Acetone a sustainable solvent for electrospinning poly (e-caprolactone) fibres effect of varying parameters and solution concentrations on fibre diameter. Journal of Polymers and the Environment 20, 879—886. 

Besides water-soluble polymers, more synthetic polymers are insoluble in water and should be dissolved in organic solvent for electrospinning, such as polylactic-co-glycolic acid (PLLA), PCL, polybutylene succinate-co-butylene terephthalate (PBST), polyhydroxyalkanoates (PHA), polybutylene succinate (PBS), PAN, poly-sulfone (PSF), polyimide (PI), polyethylene-co-vinyl alcohol (PEVA), PU, polypyrrole (PPy), polyoxymethylene (POM), PS, polymethyl methacrylate (PMMA), PVC, polyvinylidene fluoride (PVDF), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), poly A-vinylcarbazole (PVK), polymeta-phenylene isophthalamide (PMIA), polyethylene terephthalate (PET), polycarbonate (PC), polybenzimidazole (PBI), polymer vinyl acetate (PVAc), polyvinyl butyral (PVB), and polyethylene-co-vinyl acetate (PEV). 

The surface tension seems more likely to be a function of solvent compositions, but is negligibly dependent on the solution concentration. Different solvents may contribute different surface tensions. However, not necessarily a lower surface tension of a solvent will always be more suitable for electrospinning. Generally, surface tension determines the upper and lower boundaries of electrospinning window if all other variables are held constant. The formation of droplets, bead and fibers can be driven by the surface tension of solution and lower surface tension of the spinning solution helps electrospinning to occur at lower electric field [57],... 

Frey, M.W., Joo, Y., and Kim, C-W., New solvents for cellulose electrospinning and preliminary electrospinning results. Abstracts of Papers, 226th ACS National Meeting, New York, September 7 11, 2003. 

An electrospinning process was used to fabricate silk fibroin (SF) nanofiber nonwovens for wound dressing applications. The electrospinning of regenerated silk fibroin (SF) was performed with formic acid as a spinning solvent For ciystallization, as-spun SF nanofiber nonwovens were chemically treated with an... 

CHT/MWNT composite nanofihres can be fabricated by electrospinning. In our experiments, different solvents, including acetic acid (1-90%), formic acid and trifluoroacetic acid (TFA)/dichloromethane (DCM) were tested for the electrospinning of CHT/CNT. No jet was seen when applying a high voltage (even above 25 kV), with 1-30% acetic acid and formic acid as solvent for the CHT/CNT nanocomposite. 

Different solvents are employed to dissolve polyesters and to prepare the polymeric solution for electrospinning. The solvent used in polyester solutions has a great influence on its spinnability. For successful fiber formation, the solvent needs to be correctly selected. The solvent should maintain the integrity of the polymer, show good volatUity, and appropriate dielectric constant [21]. 

PCL formed a clear solution with acetic add, suggesting that the latter was a good solvent for the polymer. In the first set of experiments, the concentration of PCL in acetic add was varied from 15% to 20%. Electrospinning of these under identical conditions resulted in morphologies as shown in Fig. 2.10. At 15% concentration, mostly beads were noted. An increase in concentration to 17.5% gave a decrease in density of beads as many appeared to have been drawn into fibers. At 20% concentration, a mixture of elongated beads. 

Easy functionalisation Use of organic solvent for most of the polymers Low volume scaffolds High temperature in the case of melt electrospinning... 

Successful electrospinning requites the use of an appropriate solvent and polymer system to prepare solutions exhibiting the desired viscoelastic behavior. The traditional setup for electrospinning works well for most conventional polymers, but it cannot be easily applied to polymers with limited solubilities (e.g., conjugated polymers) or low molecular weights... 

Generally, the most profitable dispersion method is to mix the nanopaxticles into the solvent and then add and mix in the polymer destined for electrospinning. For example, Hou et al. [117] mixed SWCNTs in DMF with bath sonication. The process took 12 h to reach adequate dispersion. After ultrasonication, the polymer was added and stirred further for 12 h with a magnetic mixer. Hou et al. [117] pointed out that if the CNT concentration is too high, the fiber surface is rough because CNTs are not completely embedded in the fiber in this case. TEM micrographs of CNT embedded polyamide fibers can be seen in Figure 10.30 [118]. 

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