title: On the mechanism of floating and sliding of liquid marbles.
abstract: The mechanisms of floating and sliding of liquid marbles are studied. Liquid marbles containing CaCl(2) and marbles containing NaOH water solutions float on water containing Na(2)CO(3) and an alcoholic solution of phenolphthalein with no chemical reaction. Sliding of liquid marbles, consisting of NaOH water solutions, on polymer substrates coated with phenolphthalein is studied as well. No chemical reaction is observed. These observations supply direct experimental evidence for the suggestion that interfaces are separated by an air layer when marbles roll on solid substrates. It is concluded that a liquid marble rests on hydrophobic particles coating the liquid. In contrast, drops containing an NaOH water solution sliding on superhydrophobic surfaces coated with phenolphthalein leave a colored trace. The mechanism of low-friction sliding of drops deposited on superhydrophobic surfaces and liquid marbles turns out to be quite different: there is no direct contact between liquid and solid in the case of marbles' motion.
authors.affiliation: Ariel University Center of Samaria, Chemical and Biotechnological Engineering Faculty, Applied Physics P.O.Box 3, Ariel, Faculty, 40700, Israel. edward@ariel.ac.il
authors.forename: Edward
authors.initials: E
authors.lastname: Bormashenko
authors.forename: Yelena
authors.initials: Y
authors.lastname: Bormashenko
authors.forename: Albina
authors.initials: A
authors.lastname: Musin
authors.forename: Zahava
authors.initials: Z
authors.lastname: Barkay
mesh_terms: D000388:Air; D002122:Calcium Chloride / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D020113:Phenolphthalein / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D002254:Carbonates; D011108:Polymers; D014867:Water; C005686:sodium carbonate; D012972:Sodium Hydroxide; D020113:Phenolphthalein; D002122:Calcium Chloride