Science

Revolutionary Shape-Shifting Particles Transform Fluid Flow with Temperature Control

2025-07-02

Author: John Tan

Unlocking the Mysteries of Fluid Dynamics

Picture a liquid that can morph from a flowing stream to a thick paste at the flick of a temperature switch. Thanks to groundbreaking research from the University of Chicago’s Pritzker School of Molecular Engineering and NYU Tandon, this dream is now a reality. Scientists have engineered tiny particles that can shift their shape and stiffness on command.

Introducing the Game-Changing Material

The study, published in the prestigious Proceedings of the National Academy of Sciences, reveals a revolutionary way to manipulate the behavior of dense suspensions—mixes of solid particles within a fluid—subject to stress. These innovative particles are crafted from a unique blend of liquid crystal elastomers (LCEs), combining the structural elegance of liquid crystals with the flexibility of rubber.

From Liquid to Solid and Back Again

Dense suspensions are ubiquitous in everyday products like paints, toothpaste, and cement. Yet they can behave unpredictably, thickening under stress—an effect known as shear thickening. This can lead to disastrous manufacturing issues when consistent flow is vital.

Co-led by UChicago professor Stuart Rowan and NYU’s Juan de Pablo, the team created LCE particles designed to be programmed during their synthesis. They discovered that irregular, "potato-shaped" particles exhibited significantly more thickening under stress than smoother, "pea-shaped" counterparts.

The Breakthrough: Temperature Control

The true breakthrough came with temperature manipulation. At lower temperatures, these potato-shaped particles were rigid and thickened the suspension dramatically, resisting flow during stress. But as temperatures climbed above 45-50°C, they transformed into softer, round shapes, dramatically easing their flow.

Researchers likened the phenomenon to simple mixtures like corn starch and water, where slight shear yields a liquid state, but high shear turns it into a solid. They showcased how their stimuli-responsive particles could fine-tune a suspension's flow characteristics.

The Memory of Suspensions

Interestingly, over time—even without flow—these suspensions tend to settle into solid-like states, known as "aging." This process often complicates their usability post-storage. However, the LCE suspensions possess a unique ability: when heated above the transition temperature, they revert to their fluid state without any manual agitation.

Expanding Horizons of Application

The ability to adjust the particle shape and stiffness via temperature opens up exciting avenues for controlling dense fluids. Instead of altering the particle concentration or changing the chemical makeup of the fluid, researchers can fine-tune the same suspension just by varying the temperature. This has enormous implications for industries like 3D printing, where preventing jamming and enhancing flow is crucial.

In summary, this innovative research marks a significant leap forward in fluid dynamics, offering game-changing solutions across numerous fields. With just a bit of heat or cooling, the flow behavior of these materials can be turned from chaos to order, potentially revolutionizing how we approach fluid manipulation.