Model System (IMAGE) Helmholtz Association Caption The colloids that were used for the model: particles, each with a diameter of approximately 150 nanometers, suspended in water. The solid nucleus consists of the plastic polystyrene, the surrounding shell of a thermosensitive poly(N-isopropyl-acrylamide) network. By lowering the temperature, each individual particle's volume - and, by definition, its packing density - can be increased. Credit Photo: HZB/M. Siebenbürger Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.