title: Controlled assembly of plasmonic nanoparticles using neutral-charged diblock copolymers.
abstract: In this study, our aim was to control the assembly of plasmonic nanoparticles by using the electrostatic assembly of oppositely charged colloidal species. Gold nanoparticles (Au NPs) were modified with a carboxyl-terminated polymeric ligand, O-(2-carboxyethyl)-O'-(2-mercaptoethyl) heptaethylene glycol (SH-PEG7-COOH), so that they are negatively charged on the pH range 5-10 and they stand elevated ionic strength (up to 1M NaCl) without loss of colloidal stability. Block copolymers poly[(ethylene glycol) methyl ether-block-(N,N-dimethylamino-2-ethyl methacrylate)] (mPEG-PDMAEMA), with a neutral mPEG block and a pH-sensitive positively charged PDMAEMA block were synthesized by atom transfer radical polymerization (ATRP). The formation of complexes, driven by the electrostatic attraction between opposite charges and by the release of the condensed counter ions, was investigated using dynamic light scattering and spectrophotometry. The relative quantities of polymer chains and nanoparticles in the suspension were shown to affect the size of the formed complexes. In this report, it is also shown that the complex formation is reversible. Stable complexes of typical size 400 nm were formed, which could be used as building blocks for new optical materials.
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
authors.forename: Quanyi
authors.initials: Q
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China. Electronic address: xhan@ecust.edu.cn.
authors.forename: Xia
authors.initials: X
authors.lastname: Han
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China; CNRS, Centre de Recherche Paul Pascal, UPR 8641, 115 Avenue Schweitzer, 33600 Pessac, France; Univ. Bordeaux, Centre de Recherche Paul Pascal, UPR 8641, 115 Avenue Schweitzer, 33600 Pessac, France. Electronic address: ponsinet@crpp-bordeaux.cnrs.fr.
authors.forename: Virginie
authors.initials: V
authors.lastname: Ponsinet
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China. Electronic address: hlliu@ecust.edu.cn.
authors.forename: Honglai
authors.initials: H
authors.lastname: Liu
mesh_terms: D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000138:chemical synthesis* / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; D011092:Polyethylene Glycols
keywords: Block copolymers; Electrostatic complexation; Gold nanoparticles; Localized surface plasmon resonance; Polyelectrolytes