Dynamic Covalent Lewis Pair Grafting Enables Spontaneous Linear-to-Bottlebrush Polymer Assembly and Adaptive Elastomers

Abstract

Bottlebrush and comb-graft polymers, macromolecules with densely grafted side chains along a central backbone, exhibit distinctive conformational, rheological, and self-assembly behaviors. Although these architectures are widely used to tune mechanical responses, most reported systems rely on stable covalent carbon frameworks, or fragile supramolecular assemblies, while dynamic covalent chemistries remain largely unexplored. Herein, we harness Lewis acid–base pairs whose directional coordinate bonds drive the spontaneous assembly of graft architectures by simply mixing Lewis acid-terminated polydimethylsiloxane (PDMS) oligomers with the polymeric Lewis base poly(4-vinylpyridine) (P4VP). The PDMS-oligomers efficiently graft to the P4VP backbone. ¹¹B and ¹H NMR studies revealing a dynamic-covalent equilibrium, with rapid kinetics. Upon addition of a difunctional boronate cross-linker, the dynamically grafted polymers form stretchable elastomeric networks that can be thermally reprocessed and undergo autonomous self-healing. This Lewis-pair strategy expands bottlebrush polymer chemistry beyond static covalent and fragile supramolecular designs, with a simple, tunable route to recyclable covalent adaptable networks of soft and elastic materials.