Polymer-based nanofibers hold promise for providing improvements in a variety of applications including air filtration and protective barrier fabrics. The small diameters and resulting high surface areas of nanofibers is part of what enables them to offer benefits such as reduced air flow resistance. However, small diameter polymer-based fibers are vulnerable to chemical exposure that can degrade their properties. To this end, we have explored and developed barrier layers on electrospun polymer nanofibers. The challenge is to protect the polymer nanofibers while preserving properties such as morphology and mechanical strength.We discovered that coating processes using gas-phase reactants provide the best preservation of fiber morphology. Chemical vapor deposition (CVD) of parylene and atomic later deposition (ALD) of metal oxides were studied in more detail to develop a coating process that provided the best balance of chemical resistance, mechanical properties, and morphology preservation. ALD of aluminum oxide was found to provide the best results for electrospun polysulfone nanofibers.We will discuss the metrics and results of morphology preservation, chemical resistance, and mechanical properties. As shown in Figure 1 , an ALD coating was developed that protected the fibers against solvent exposure while retaining excellent fiber morphology. These fibers were also found to be semi-flexible. Example data for the application of air filtration will also be shared. Figure 1.  SEM of uncoated (control) and ALD coated polysulfone nanofibers exposed to toluene (a good solvent for polysulfone). ALD coated fibers have both chemical resistance and good morphology.

Coatings for electrospun nanofibers for use in harsh environments

247th National Meeting (2014)

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