(604f) Bottom-up Fabrication of Flexible and Porous Omniphobic Interfaces Via Sequential Initiated Chemical Vapor Deposition

Omniphobic surfaces repel most liquids with a broad spectrum of polarity. However, creating reentrant structures on flexible and porous substrates poses a significant challenge to the scalable fabrication of omniphobic membranes.^1,2 Designing such membranes, in addition to forming reentrant structures on the surface, necessitates careful consideration of the surface chemistry of the porous matrices. Here, we developed a process–Sequential initiated Chemical Vapor Deposition (S-iCVD)–to impart the desired chemical and structural properties to a porous substrate. By adjusting the reaction rate and processing conditions, we demonstrate exceptional control over the properties of membranes and coatings. The chemistry of the coated materials was confirmed using Fourier-transformed infrared-spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) methods. The omniphobic properties of the fabricated membranes were examined using different liquids with surface energies ranging from 72 mN m^-1 to 22 mN m^-1. The omniphobic structures hindered intrusion of the large droplets (1.5-1.8 mm) of low surface energy liquids (e.g., Ethanol) impacted the surface with a velocity of around 2 m/s. By evaluating the performance of the developed omniphobic membranes in the direct contact membrane distillation (DCMD) process, we report on the continuous distillation of a contaminated water sample for an extended period of time, exceeding a week, without any change in the membrane performance.

References

(1) Wilke, K. L.; Preston, D. J.; Lu, Z.; Wang, E. N. Toward Condensation-Resistant Omniphobic Surfaces. ACS Nano 2018, 12 (11), 11013–11021.

(2) Hensel, R.; Neinhuis, C.; Werner, C. The Springtail Cuticle as a Blueprint for Omniphobic Surfaces. Chem. Soc. Rev. 2016, 45 (2), 323–341.