title: Interfacial Activity of Gold Nanoparticles Coated with a Polymeric Patchy Shell and the Role of Spreading Agents.
abstract: Gold patchy nanoparticles (PPs) were prepared under surfactant-free conditions by functionalization with a binary ligand mixture of polystyrene and poly(ethylene glycol) (PEG) as hydrophobic and hydrophilic ligands, respectively. The interfacial activity of PPs was compared to that of homogeneous hydrophilic nanoparticles (HPs), fully functionalized with PEG, by means of pendant drop tensiometry at water/air and water/decane interfaces. We compared interfacial activities in three different spreading agents: water, water/chloroform, and pure chloroform. We found that the interfacial activity of PPs was close to zero (∼2 mN/m) when the spreading agent was water and increased to ∼14 mN/m when the spreading agent was water/chloroform. When the nanoparticles were deposited with pure chloroform, the interfacial activity reached up to 60 mN/m by compression. In all cases, PPs exhibited higher interfacial activity than HPs, which were not interfacially active, regardless of the spreading agent. The interfacial activity at the water/decane interface was found to be significantly lower than that at the water/air interface because PPs aggregate in decane. Interfacial dilatational rheology showed that PPs form a stronger elastic shell at the pendant drop interface, compared to HPs. The significantly high interfacial activity obtained with PPs in this study highlights the importance of the polymeric patchy shell and the spreading agent.
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada , 18001 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Fernández-Rodríguez
authors.affiliation: CIC biomaGUNE, Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain; Department of Chemistry, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marquês de São Vicente, 225, Rio de Janeiro, RJ 22451-900, Brazil.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Percebom
authors.affiliation: CIC biomaGUNE , Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Giner-Casares
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada , 18001 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Rodríguez-Valverde
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada , 18001 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Cabrerizo-Vílchez
authors.affiliation: CIC biomaGUNE, Paseo de Miramón 182, 20009 Donostia-San Sebastián, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Liz-Marzán
authors.affiliation: Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada , 18001 Granada, Spain.
authors.forename: Roque
authors.initials: R
authors.lastname: Hidalgo-Álvarez