AFRL Funds Research of Oil-Repellent Surfaces

  • Published
  • By Maria Callier
  • AFOSR
ARLINGTON, Va. --  AFRL is sponsoring investigations of super-oil-repellent surfaces for their potential utility in cleaning up jet fuel spills and protecting aircraft or rocket parts from fuel absorption. Dr. Gareth H. McKinley and Dr. Robert E. Cohen, professors of engineering at the Massachusetts Institute of Technology (MIT), are exploring man-made and natural surfaces that prevent gasoline and oil from soaking in and spreading out. The challenge lies in the low value of surface tension characteristic to many oils. Surface tension is a measure of the attraction existing between molecules of the same composition; the low value of surface tension (i.e., weak molecule attraction) inherent to most oils permits them to spread very easily over surfaces. Consequently, the researchers' goal is to design new solid surfaces exhibiting very low interfacial energies and thus capable of repelling oily liquids.

After studying the water-repellent surfaces of lotus leaves, Drs. McKinley and Cohen created a microfiber fabric that can be deposited onto aircraft surfaces via a process known as electrospinning. The microfibers contain fluorinated nanoparticles--specifically, FluoroPOSS, or fluorinated polyhedral oligomeric silsesquioxanes--synthesized by Dr. Joe Mabry and colleagues at Edwards Air Force Base, California.

The combination of the involved chemistry on the nanoscale level and corresponding fiber structure on the micrometer scale gives rise to the new material's oil-repelling nature. Research exploring oil-repellent surfaces is critical for many Air Force systems. This collaborative effort between scientists at MIT and AFRL marks an important steps towards achieving future systems that are more maintenance-free.

The scientists' work may ultimately lead to protective coatings for airplane parts, which are vulnerable to fuel leaks. The research may also prompt the creation of fuel-line gaskets based on the new technology, since currently available gaskets typically swell substantially when they absorb gasoline. Such material-related innovations will greatly reduce the maintenance effects of fuel spills, making cleanup of fuel or oil-soaked equipment significantly easier.