title: Cross-linked polynorbornene-coated gold nanoparticles: dependence of particle stability on cross-linking position and cross-linker structure.
abstract: This paper describes the preparation of cross-linked polynorbornene coated gold nanoparticles. The polymer was grown radially from the particle surface using a ring opening metathesis polymerization of norbornene and an electrophilic norbornene ester, which was cross-linked using a variety of diamines. The stability of the cross-linked nanoparticles toward oxidative etching by cyanide was evaluated. The rate of etching decreases as diamines with fewer degrees of conformational freedom are used as cross-linkers. The distance of the cross-linking block from the nanoparticle surface was systematically varied. Nanoparticles with the cross-linked block furthest from the surface were etched most slowly. This is suggested to arise as a result of the polymers adopting a mushroom conformation when the cross-linking block is close to the particle surface, while more distal cross-linking results in more rigid polymer chains that are less permeable to the cyanide etchant. These results provide new insight into how fine-tuning the polymer cross-linking architecture can modulate nanoparticle stability.
authors: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors: Xiang
authors: X
authors: Liu
authors: Amit
authors: A
authors: Basu
mesh_terms: D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003486:Cyanides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D015394:Molecular Structure; D010316:Particle Size; D010969:Plastics / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D003486:Cyanides; D008024:Ligands; D010969:Plastics; C071464:polynorbornen; D006046:Gold