posted on 2022-03-11, 21:16authored byJingcheng Ma, Zhuoyuan Zheng, Muhammad Jahidul Hoque, Longnan Li, Kazi Fazle Rabbi, Jin Yao Ho, Paul V. Braun, Pingfeng Wang, Nenad Miljkovic
Creating
thin (<100 nm) hydrophobic coatings that are durable
in wet conditions remains challenging. Although the dropwise condensation
of steam on thin hydrophobic coatings can enhance condensation heat
transfer by 1000%, these coatings easily delaminate. Designing interfaces
with high adhesion while maintaining a nanoscale coating thickness
is key to overcoming this challenge. In nature, cell membranes face
this same challenge where nanometer-thick lipid bilayers achieve high
adhesion in wet environments to maintain integrity. Nature ensures
this adhesion by forming a lipid interface having two nonpolar surfaces,
demonstrating high physicochemical resistance to biofluids attempting
to open the interface. Here, developing an artificial lipid-like interface
that utilizes fluorine–carbon molecular chains can achieve
durable nanometric hydrophobic coatings. The application of our approach
to create a superhydrophobic material shows high stability during
jumping-droplet-enhanced condensation as quantified from a continual
one-year steam condensation experiment. The jumping-droplet condensation
enhanced condensation heat transfer coefficient up to 400% on tube
samples when compared to filmwise condensation on bare copper. Our
bioinspired materials design principle can be followed to develop
many durable hydrophobic surfaces using alternate substrate-coating
pairs, providing stable hydrophobicity or superhydrophobicity to a
plethora of applications.