ICE-CAP: ice crystal engineering for cryogel architecture programming. Modulation of material properties with ice-binding polymers.

Macroporous cryogels are formed by polymerising monomers around ice crystal templates, with water as the only waste product, making them appealing as tuneable and sustainable scaffolds. Cryogels have found diverse applications spanning pollutant removal, vaccine delivery, tissue culture and purification. However, an unmet challenge remains: ice crystal templates are intrinsically dynamic and evolve during polymerisation, leading to heterogeneity and complicating reproducibility. Here we overcome this challenge using ice-binding protein-inspired polymers that pre-program the ice crystal template size within cryogels through selective ice crystal surface binding. This ice-crystal programming is shown to fine-tune the rheological and mechanical properties of the resulting materials, without any change in the monomer composition or extensive optimization of reaction conditions, unlike conventional methods. This approach unlocks wider applications of cryogels, exploiting biomimetic solutions to tune the crucial ice crystal template.