Ice binding proteins modulate ice nucleation/growth and have huge (bio)technological potential. There are only a few synthetic materials that reproduce their function, and rational design is challenging due to the outstanding questions about the mechanisms of ice-binding. Poly(vinyl alcohol) (PVA) is a water-soluble synthetic polymer well-known to effectively block the recrystallization of ice, by binding to ice. Herein, we report the synthesis of core-shell bottlebrush copolymers containing poly(vinyl alcohol) via a combination of ring-opening metathesis polymerization (ROMP) and reversible addition-fragmentation chain transfer (RAFT) polymerization, using “grafting-to” and “grafting-through” approaches to develop bottlebrush copolymers with different densities. The facile preparation of the PVA bottlebrushes was performed via selective hydrolysis of the acetate esters of the poly(vinyl acetate) (PVAc) side chains of the PVAc bottlebrush precursors. We demonstrate that densely grafted PVA bottlebrush polymers not only showed increased ice recrystallization inhibition activities, but can also nucleate ice, and are the first example of a synthetic soluble ice nucleator. Lower density graft PVA copolymers prepared by “grafting-to” strategy using a pre-formed backbone had less nucleation activity, as did PEG-based brush controls. This shows that soluble synthetic macromolecular ice nucleators could be designed and synthesized with huge potential in cryopreservation, but to also understand the mechanisms of ice nucleation.

Poly(vinyl alcohol)-based molecular bottlebrushes nucleate ice

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.