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Ice formation can damage biological samples, tissues and materials during freezing and thawing. In nature, specialised molecules known as ice鈥慴inding proteins prevent ice crystals from growing too large, helping organisms survive in extreme cold.

Scientists have long tried to replicate this behaviour using synthetic materials, but most designs have focused on how molecules interact with ice at their surface.

In a study published in , the team 鈥� led by 鈥�  have shown for the first time that the internal structure of polymer nanoparticles, rather than their outer surface, plays a key role in controlling ice growth. This was a collaboration with Professor Steve Armes FRS at Sheffield Univeristy.

Looking inside the particle

The team created a library of polymer nanoparticles using a scalable technique known as polymerisation鈥慽nduced self鈥慳ssembly. These particles consist of a water鈥慹xposed outer layer and a hidden inner core.

Surprisingly, the researchers found that changing the chemistry of the inner core dramatically altered how effectively the particles inhibited ice recrystallisation 鈥� the process by which ice crystals grow larger over time.

Particles with 鈥渟oft鈥� cores showed significantly higher activity, strongly suppressing ice growth, while those with more rigid cores were less effective.

Even more strikingly, chemically locking the core structure removed this activity entirely.

A new design principle

The findings challenge the conventional view that only the surface of a material interacts with ice. Instead, they show that internal mobility and structure within nanoparticles can influence how ice crystals behave.

The study suggests that individual polymer chains within the particles may play a role in interacting with ice as conditions change during freezing and thawing.

Applications from medicine to materials

Materials that control ice growth are important in a wide range of applications, from preserving cells and tissues to improving the texture of frozen foods and developing anti鈥慽cing coatings.

By providing a new way to design these materials, the research opens up opportunities to develop more effective, scalable and cost鈥慹fficient alternatives to natural antifreeze proteins.

The work also establishes a broader framework for designing functional nanoparticles, showing that internal structure can be as important as surface chemistry in determining performance.