The research is part of the COLIS project, which aims to analyze the impact of gravity on creamy product formulations.
Your sunscreen sits in the bathroom cabinet, changing slowly. The mayonnaise in your refrigerator will gradually separate. That prescription cream loses effectiveness over time. All these materials share something fundamental: they are soft matter, substances such as gels, foams and colloids whose internal structure reorganizes slowly and mysteriously over months or years.
Understanding exactly what happens inside these materials as they age has always been complicated by gravity. Even sitting on a shelf, the Earth’s gravitational force constantly influences the way in which the particles within these substances deposit, group and reorganize. Therefore, a team of researchers from the Politecnico di Milano and the Université de Montpellier decided to study soft matter in a place where gravity had no effect.
The result is COLIS, a new experimental facility which operates aboard the International Space Station. The laboratory represents the culmination of more than 25 years of collaboration between Luca Cipelletti, a physicist at the Laboratoire Charles Coulomb, and Roberto Piazza, who heads the Soft Matter laboratory at the Politecnico di Milano.
COLIS uses sophisticated optical techniques to observe the interior of materials without disturbing them. Dynamic light scattering analysis examines how laser beams pass through the samplesrevealing tiny variations called speckle patterns that show how gels and other soft materials restructure over time. The facility can also carefully heat samples to trigger aging processes in a precise and reproducible way, observing what happens at the molecular level.
The first results have already surprised the research team. Gravity affects the structure of soft matter more drastically than expectedinfluencing the properties of materials even over long periods of time.
“It’s incredible to see how much gravity, so familiar in our everyday lives, works behind the scenes to shape the materials we use every day,” said Roberto Piazza, from the Soft Matter Laboratory at Politecnico di Milano.
Pharmaceutical companies need medicines that remain stable for years. Cosmetics manufacturers want creams that don’t separate. Food producers need emulsions that maintain consistency during distribution and storage. Understanding how these materials actually behave when gravity is not constantly interfering could revolutionize formulation development.
Transported to the International Space Station, COLIS is now analyzing samples of ideal colloidal nanoparticles to investigate internal reorganization and aging. The project operates within the scope of the European Space Agency’s “Colloids in Space” program, with the support of the Italian and French space agencies.
