title: Reversible controlled assembly of thermosensitive polymer-coated gold nanoparticles.
abstract: Aggregation of thermosensitive polymer-coated gold nanoparticles was performed in aqueous solution in the presence of a triblock copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic P123, PEO(20)-PPO(68)-PEO(20)). The gold nanoparticles, AuNPs, which are covered by thermosensitive statistical copolymers poly(EO(x)-st-PO(y)), aggregate when the temperature is higher than the phase transition temperature of the polymer, leading to a macroscopic precipitation. The presence of Pluronic chains in solution prevents the uncontrolled aggregation of the AuNPs at higher temperature than both the aggregation temperature of the AuNPs (T(agg)) and the critical micellization temperature (cmt) of the Pluronic. The size, the colloidal stability, and the optical properties of the AuNPs aggregates are modulated as a function of the P123-to-AuNP ratio, which constitutes the critical parameter of the system. Moreover, the AuNP aggregation is totally reversible upon decreasing the temperature below T(agg). Our approach constitutes an easy way to the formation of well-controlled nanoparticle aggregates with well-defined sizes. The resulting aggregates have been characterized by UV-vis spectroscopy, dynamic light scattering, and electron microscopy.
authors: Laboratoire de Physico-chimie des Polymères et Milieux Dispersés-Sciences et Ingénierie de la Matière Molle, UMR7615, UPMC Sorbonne Universités, ESPCI ParisTech, CNRS, 75231 Paris Cedex 05, France.
authors: Céline
authors: C
authors: Durand-Gasselin
authors: Nicolas
authors: N
authors: Sanson
authors: Nicolas
authors: N
authors: Lequeux
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D011060:Poloxalene / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; C464484:pluronic block copolymer P123; D006046:Gold; D011060:Poloxalene; D015126:8,11,14-Eicosatrienoic Acid