Enhancing iCVD Modification of Electrospun Membranes for Membrane Distillation through a 3D Printed Scaffold

In this work, initiated chemical vapor deposition, iCVD, is used as a modification technique for electrospun membranes. Electrospun membranes are often hydrophilic and cannot be used in membrane distillation which requires high hydrophobicity. In membrane distillation, a thermal driving force is supplied to create a vapor pressure difference across a membrane allowing vapor molecules to pass through while rejecting liquid and solids. iCVD can be used to conformally coat the individual nanofibers with a hydrophobic polymer to render the membrane viable for the MD process. The standard coating procedure uses natural convective diffusion as the method of transport of the hydrophobic coating monomer to the membrane. This procedure requires two sides of coating to achieve adequate hydrophobicity. We have altered this process by implementing a 3D printed scaffold to change the coating orientation of the membrane to force convective flow through the membrane effectively coating the membrane faster than traditional natural convective diffusion. It was found that this process reduced the coating time to 20 minutes compared to 200 minutes previously required for this membrane. It also eliminated the need to coat both sides of the membrane further reducing the process dead time. The membranes, themselves, also exhibited 100% salt rejection and a competitive flux value.