Marangoni Effect in the Water Wetting of Surfactant Coated Human Hair Fibers

In the 1984 study, researchers investigated the wetting behavior of human hair fibers coated with a cationic surfactant and found that the stick-slip nature of wetting force curves was due to the Marangoni effect, caused by the desorption of the surfactant from the fiber surface into the water. This effect led to fluctuations in the wetting force and apparent changes in contact angle. The study showed that the amplitude and frequency of the stick-slip were influenced by the surfactant's distribution and binding to the fiber surface. It was also determined that the stick-slip pattern was specific to the desorption of surface-active material rather than the hair's scale structure or non-surface-active materials. The study observed Marangoni flows qualitatively but did not provide a theoretical analysis or the number of hair fibers tested.