Dynamic Covalent Polymer Films Formed by Structural Metamorphosis at Nanoparticle Surfaces

Abstract

Wrapping nanoscale objects within robust polymer films offers a powerful strategy to control surface properties, stability and functionality, yet achieving uniform, individually wrapped nanoparticles remains challenging. Here we report the first example of nanoparticle wrapping using dynamic covalent single-chain polymer nanoparticles (SCPNs) that undergo a concentration-triggered 'structural metamorphosis' into an intermolecularly-crosslinked polymer film at the particle surface. Imidazole-decorated SCPNs bind multivalently to Ni-NTA-functionalised silica nanoparticles, where confinement and local concentration induce dynamic acylhydrazone exchange, transforming intramolecular crosslinks into intermolecular ones. As well as dynamic light scattering and zeta potential measurements, tranmission electron miscroscopy confirms the formation of monodisperse, individually wrapped nanoparticles bearing thin, stable polymer shells that cannot be displaced by competitive ligands. In contrast, non-crosslinked imidazole-functionalised polymers are only able to form coatings that are largely removed. This strategy provides a versatile platform for creating nanoparticle wrappers and establishes a conceptual framework for extending polymer wrapping to complex and biologically relevant nanoscale objects.