Cross-Linked Polynorbornene-Coated Gold Nanoparticles: Dependence of Particle Stability on Cross-Linking Position and Cross-Linker Structure
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文摘
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.