A general synthesis of cyclic bottlebrush polymers with enhanced mechanical properties graft-through ring expansion metathesis polymerization.

Bottlebrush polymers represent an important class of macromolecular architectures, with applications ranging from drug delivery to organic electronics. While there is an abundance of literature describing the synthesis, structure, and applications of linear bottlebrush polymers using ring-opening metathesis polymerization (ROMP), there are comparatively less reports on their cyclic counterparts. This lack of research is primarily due to the difficulty in synthesizing cyclic bottlebrush polymers, as extensions of typical routes towards linear bottlebrush polymers (, "grafting-through" polymerizations of macromonomers with ROMP) produce only ultrahigh molar mass cyclic bottlebrush polymers with poor molar mass control.

Liquid-assisted grinding enables a direct mechanochemical functionalization of polystyrene waste.

The plastic waste crisis has grave consequences for our environment, as most single-use commodity polymers remain in landfills and oceans long after their commercial lifetimes. Utilizing modern synthetic techniques to chemically modify the structure of these post-consumer plastics (, upcycling) can impart new properties and added value for commercial applications. To expand beyond the abilities of current solution-state chemical processes, we demonstrate post-polymerization modification of polystyrene solid-state mechanochemistry enabled by liquid-assisted grinding (LAG).

Diaryliodonium salts facilitate metal-free mechanoredox free radical polymerizations.

Mechanically-induced redox processes offer a promising alternative to more conventional thermal and photochemical synthetic methods. For macromolecule synthesis, current methods utilize sensitive transition metal additives and suffer from background reactivity. Alternative methodology will offer exquisite control over these stimuli-induced mechanoredox reactions to couple force with redox-driven chemical transformations.