Electrospinning and application of cyanoacrylate fibers

Cyanoacrylate, also known commonly as superglue, is a family of fast acting adhesives with industrial, medical and household uses. When combined with electrospinning, cyanoacrylate fibers and its architecture have the potential to expand and improve the applications of this material. While most electrospun materials have difficulties with bonding to a substrate, the nature of cyanoacrylate renders this a lesser problem. Development and investigation of electrospun cyanoacrylate has resulted in several interesting applications.

Early attempt to electrospin cyanoacrylate uses a higher molecular weight polymer to blend with cyanoacrylate such that the solution has sufficient viscosity to form fibers. Liu et al (2013) used the mixture poly(ethyl-2-cyanoacrylate)/polymethylmethacrylate (PECA/PMMA) for electrospinning without using any other solvent. In this case, PECA function as the solvent for dissolving PMMA. During electrospinning, rapid polymerization of the ECA monomer in the presence of water vapor causes the solidification of the mixture. Since this combination does not require the use of any solvents, it provides a method of producing environmentally friendly nanofibers.

Medical grade cyanoacrylate has been routinely used clinically for managing wounds. In the form of a fibrous network, cyanoacrylate fibers have the potential for bridging larger wound and to arrest blood lost. In the presence of a gas jet, the electrospinning jet is being accelerated in a singular direction towards the collector surface despite the conical evolution of the jet due to the electrostatic charges. The reduced flight time pushes the electrospinning jet to deposit on the collector before the conical path expands. This characteristic of electroblowing makes it favorable for applying medical cyanoacrylate glue on a wound for rapid closure. Jiang et al (2014) successfully demonstrated such an application for rapid hemostasis in liver resection. The electrospun coating was able to arrest blood seepage from the wound. Lv et al (2016) showed that with electroblowing of N-octyl-2-cyanoacrylate, the deposition width can be narrowed to 4 mm when the electrospinning distance was 2 cm. As the electrospinning distance increases, so was the fiber deposition width. At a distance of 6 cm, the deposition width was increased to 12 mm. This was still much smaller than conventional electrospinning which typically has a deposition width of 50 mm or more. With such narrow width, they were able to demonstrate sealing of dural defects while avoiding tissue adhesion.

Electrospun fibers have been tested as a coating for anti-fogging or self-cleaning surfaces. However, a major limitation for this application for electrospun coating is the durability of such coating. Given that cyanoacrylate adheres to most material, its electrospun fibers may potentially address this limitation and exhibit the same self-cleaning properties. Mele et al (2015) was able to electrospin pure poly(ethyl 2-cyanoacrylate) (PECA) by zwitterionic polymerization of ethyl 2-cyanoacrylate (ECA) monomers in dimethyl sulfoxide (DMSO) and dilution with acetone. The resultant electrospun fibrous coating can be thermally transformed into a transparent and textured surface with hydrophilic and self-cleaning property. On a glass substrate, the heat treated transparent electrospun coating demonstrated a sliding angle of 40 °.

Anti-staining performances of the PECA textured coatings. (a) Experimental data (grey circles) of the cosine of the contact angle as function of the surface tension of the analyzed liquids. The solid line is the best linear fit of the data. (b) Experimental data (grey circles) of the contact angle hysteresis as function of the sliding angle. (c) Photograph of drops of water impacting and sliding on two glass substrates: one coated with the thermally treated PECA fibers (sample on the right) and the other one uncoated (sample on the left). Scale bar = 0.5 cm. (d) Temporal sequence showing a double-side coated glass substrate pulled out from a water bath. The water was colored in red for visualization purposes. Scale bar = 0.5 cm. [Mele, E. et al. Zwitterionic Nanofibers of Super-Glue for Transparent and Biocompatible Multi-Purpose Coatings. Sci. Rep. 5, 14019; doi: 10.1038/srep14019 (2015). This work is licensed under a Creative Commons Attribution 4.0 International License.]

Another interesting property of the electrospun PECA coating is its low friction coefficient (0.23) [Mele et al 2015]. Using a stainless steel tip, the friction coefficient of the electrospun PECA coating was lower than conventional solid polymer films lubricants and comparable to polytetrafluoroethylene (PTFE). Considering that electrospun fibers coating using other materials have shown good shear adhesive properties, it is interesting to note that electrospun PECA coating have a contrasting result.

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