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. Dynamic light scattering, zeta potential measurements and transmission electron microscopy confirm 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.