Surface activity and collective behaviour of colloidally stable Janus-like particles at the air-water interface Fernández Rodríguez, Miguel Ángel Rodríguez Valverde, Miguel Ángel Cabrerizo Vílchez, Miguel Ángel Hidalgo Álvarez, Roque Isidro This work was supported by MINECO, MAT2010-15101 and MAT2011-23339 projects (Spain) and by “Junta de Andalucía” and FEDER under project P10-FQM-5977. In this work we report an experimental study on the surface activity and the collective behaviour of colloidally stable Janus-like silver particles at the air-water interface. The colloidal stability of silver nanoparticles has been enhanced using different capping ligands. Two polymers coated the silver particles: 11-mercaptoundecanoic acid and 1-undecanthiol. These capping ligands adsorbed onto the particle surface are spontaneously rearranged at the air-water interface. This feature leads to Janus behaviour in the silver particles with amphiphilic character. The surface activity of the silver particles at the air-water interface has been measured using pendant drop tensiometry. The Janus-like silver particles revealed a surface activity similar to that shown by conventional amphiphilic molecules but at much larger area per particle. The variation of the surface pressure with the area per particle was described properly using the Frumkin isotherm up to the collapse state. Furthermore, oscillating pendant drop tensiometry provided very useful data on the rheological properties of Janus particle monolayers; these properties depended on the lateral interactions between particles and were closely related to the monolayer microstructure. We revealed the close relationship between the collective behavior and the surface activity of Janus-like silver particles. 2024-02-26T10:47:10Z 2024-02-26T10:47:10Z 2014 info:eu-repo/semantics/article Published version: Fernández Rodríguez, Miguel Ángel et al. Surface activity and collective behaviour of colloidally stable Janus-like particles at the air-water interface. Soft Matter, 2014,10, 3471-3476. DOI: https://doi.org/10.1039/C3SM52624K https://hdl.handle.net/10481/89575 10.1039/C3SM52624K eng http://creativecommons.org/licenses/by-sa/4.0/ info:eu-repo/semantics/openAccess Atribución-CompartirIgual 4.0 Internacional