Ученые научились управлять структурой стеклоподобных материалов с помощью температурного шока

BENGALURU: Imagine a crowded room where nobody can move. Now imagine briefly opening enough space for everyone to rearrange themselves before the room becomes crowded again. Scientists at the Raman Research Institute (RRI) in Bengaluru have found a way to do something similar with tiny particles packed so tightly that they behave like glass. The finding by a team led by Prof Ranjini Bandyopadhyay and Sonali Kawale, a PhD student and the first author of the study and other researchers at RRI, could eventually help scientists better control materials used in applications such as targeted drug delivery. The study was published in the Journal of Colloid and Interface Science. Glass is an unusual material. It behaves mechanically like a solid, but its internal structure is disordered, more like that of a liquid. Such materials can also retain a kind of memory of the changes they have undergone. Scientists have long been interested in finding ways to erase these imprints and temporarily make such jammed systems flow, allowing their structure to be controlled. The RRI researchers explored this question using microscopic, soft particles called microgels. These particles can absorb 300 to 500 times their weight in water and are already used in products such as diapers and sanitary napkins. The team packed the particles tightly enough to create a jammed system, in which the particles could not move freely. But when researchers suddenly changed the rate at which the temperature was raised, effectively giving the material a thermal shock, the particles rearranged themselves. For a brief period, the jammed material behaved more like a liquid. This rearrangement also erased the system’s memory of how it had reached a particular temperature. In their experiments, researchers found that heating and cooling the suspension to the same target temperature of 20°C did not necessarily produce the same result. The path taken mattered. The structure followed one route while heating and another while cooling, an effect scientists describe as asymmetry. By introducing a sudden change in the temperature ramp, however, the team could reduce these differences and gain greater control over how the material recovered its structure. That could matter in medicine. Microgels can be used to carry drugs and release them when conditions change. When cool, the particles can swell and hold a drug. When heated above about 34°C, just below normal body temperature, they can collapse and squeeze out their contents. This makes them potentially useful for delivering medicines at specific locations in the body, including tumours, while reducing exposure to healthy tissue. Understanding how such particles respond to sudden temperature changes could therefore help researchers design drug-delivery systems that are more predictable and controllable. The team will next examine how these jammed materials respond to mechanical shocks and compare those effects with temperature shocks. For now, the study offers a simple insight: sometimes, to make a crowded system behave differently, all it may need is a carefully timed shock.