A mechanochemically created durable dynamic superhydrophilic-like surface

Superhydrophilicity (superwettability) is generally defined as either a static water contact angle near 0 degrees or water completely wetting the surface. Here, we show that there is a superhydrophilic-like surface that has a large static water contact angle but demonstrates superhydrophilicity in its dynamic water contact performance. We found that polyethylene terephthalate (PET) surfaces showed such behavior following mechanical abrasion with sandpaper. We have evaluated the wettability of the abraded PET surfaces by using static water contact angle (SWCA) measurements and the dynamic water contact performance (DWCP) of impacting droplets, the latter including water sprays, water immersion, anti-fogging and water droplet impact tests. The water was found to completely wet the abraded PET surfaces on spraying or immersion, although the measured SWCA was as high as 70 degrees, similar to that of the unabraded PET surface. For the abraded PET surface, both the water layer thickness on water immersion and the subsequent drying time were similar to those of an especially coated superhydrophilic layer on the unabraded surface. Accordingly, superhydrophilicity may be determined by the process used to measure it.

Automated summary

We have discovered a surface that exhibits superhydrophilic behavior despite having a large static water contact angle. This phenomenon occurs when polyethylene terephthalate surfaces are mechanically abraded with sandpaper. Despite having a high contact angle, the abraded surfaces can still be completely wetted by water.