A Review on the Impact of Humidity during Electrospinning: From the Nanofiber Structure Engineering to the Applications

Abstract

Electrospinning is the process of choice for the elaboration of nanofibrous mats. During the process, a thin and continuous charged jet of a polymer solution is travelling from an emitter subjected to a high voltage towards a grounded collector.Although the duration of the jet travel is in the order of few tens of milliseconds, the physical interactions acting between the jet and the air play a key role on the resulting fiber morphology. These interactions mainly rely on the amount of water molecules in air. This review deals with the effect of humidity during electrospinning on solvent evaporation, the solidification rate of nanofibers and finally, on the morphology at length scales ranging from the non-woven mat, the nanofiber itself down to the polymer crystal.Original electrospinning processes operating under specific environmental conditions as well as the specificities encountered in needleless and free-surface electrospinning dedicated to industrial scale mass production are also discussed. Then, it is shown how the control of humidity during electrospinning and the understanding of its influence on the fibrous structure can be exploited to target various applications dedicated to energy, environment and health. Finally, current challenges and ideas for future research and new developments are presented.

Reduced-Pressure Process for Fabricating Tea Tree Oil—Polyvinylpyrrolidone Electrospun Fibers

“…Here, since PVP can be dissolved in water, the moisture absorption around PVP was less under a low RH. Therefore, as the PVP solidified, the electrospun fiber cannot be elongated anymore, resulting in thicker fibers [53], which agrees with our observations in this study.…”

Ambient Climate Influences Anti-Adhesion between Biomimetic Structured Foil and Nanofibers

“…In general, lower humidity seems to be most beneficial for minimizing adhesion. This is particularly interesting as low humidity is advantageous for the production of nanofibers and has a positive effect on the fiber diameter [53,54]. The ideal relative humidity for electrospinning of commonly used polymers seems to be at 30% [55].…”

Osteochondral Tissue Engineering: The Potential of Electrospinning and Additive Manufacturing

“…Potential pitfalls associated with electrospinning include poor control over scaffold architecture, difficulty in producing 3D structures, and usually small pore size that may hinder cell penetration and migration, as well as nutrient circulation and waste removal [298,300]. The process is also highly dependent on environmental parameters such as temperature and humidity, which can be difficult to control [276,301]. Additionally, most electrospinning techniques make use of organic solvents, due to their higher volatility and lower surface tensions facilitating the electrohydrodynamic extrusion of the polymer solution and ensuring efficient solvent evaporation during fibre formation.…”