Ultra-Low Dispersity Poly(vinyl alcohol) Reveals Significant Dispersity Effects on Ice Recrystallization Inhibition Activity.

Polymer mimics of antifreeze proteins are emerging as an exciting class of macromolecular cryoprotectants for the storage of donor cells and tissue. Poly(vinyl alcohol), PVA, is the most potent polymeric ice growth inhibitor known, but its mode of action and the impact of valency (DP) are not fully understood. Herein, tandem RAFT polymerization and column chromatography are used to isolate oligomers with dispersities <1.01 to enable the effect of molecular weight distribution, as well as length, to be probed. It is found that polymers with equal number average molecular weight, but lower dispersity, have significantly less activity, which can lead to false positives when identifying structure-property relationships. The minimum chain length for PVA's unique activity, compared to other non-active poly-ols was identified. These results will guide the design of more active inhibitors, better cryopreservatives and a deeper understanding of synthetic and biological antifreeze macromolecules.