Nanowerk  October 23, 2023
Surface heterogeneity is generally acknowledged as the major cause of increased contact angle hysteresis and contact line friction of droplets. An international team of researchers (Finland, Japan) have shown that tuning the coverage of self-assembled monolayers (SAMs), water contact angles changed gradually from about 10° to 110° yet contact angle hysteresis and contact line friction were low for the low-coverage hydrophilic SAMs as well as high-coverage hydrophobic SAMs. Their slipperiness was not expected based on the substantial chemical heterogeneity of the SAMs featuring uncoated areas of the substrate well beyond the size of a water molecule as probed by metal reactants. According to molecular dynamics simulations, the low friction of both low- and high-coverage SAMs originates from the mobility of interfacial water molecules. According to the researchers their findings reveal a yet unknown and counterintuitive mechanism for slipperiness, opening new avenues for enhancing the mobility of droplets… read more. Open Access TECHNICAL ARTICLE
Graphical abstract. Credit: Nature Chemistry, 23 October 2023Â