Synthesis, characterization and evaluation of urethane co-oligomers containing pendant fluoroalkyl ether groups

• Urethane co-oligomers containing fluorinated surface modifying agents developed.
• Urethane co-oligomers used to develop coatings with abhesive properties.
• Wind tunnel testing used to gauge coatings ability resist insect residue adhesion.
• Urethane co-oligomer coatings displayed a resistance to insect residue adhesion.

Coatings with the ability to minimize adhesion of insect residue and other debris are of great interest for future aircraft. These aircraft will exhibit increased fuel efficiency by maintaining natural laminar flow over greater wing chord distances. Successful coatings will mitigate the adhesion of debris on laminar flow surfaces that could cause a premature transition to turbulent flow. The use of surface modifying agents (SMA) that thermodynamically orient towards the air side of a coating can provide specific surface chemistry that may lead to a reduction of contaminate adhesion. Aluminum surfaces coated with urethane co-oligomers containing various amounts of pendant fluoroalkyl ether groups were prepared, characterized and tested for their abhesive properties. The coated surfaces were subjected to controlled impacts with wingless fruit flies (drosophila melanogaster) using both a benchtop wind tunnel and a larger-scale wind tunnel test facility. Insect impacts were recorded and analyzed using high-speed digital photography and the remaining residues characterized using optical surface profilometry and compared to that of an aluminum control. It was determined that using fluorinated oligomers to chemically modify coating surfaces altered the adhesion properties relative to the adhesion of insect residues to the surface.

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