"Until our work, there has been no clear and simple example that rigorously demonstrates the effect of competing property demands on composite microstructures," said Princeton's Salvatore Torquato.
The scientists calculated the optimum structure for a two-phase composite with good electrical and heat conduction. Although a number of materials have high electrical and thermal conductivity, the team deliberately picked two starting materials with a high value of only one of these properties.
Surprisingly, the results showed that a complex shape - a "bicontinuous triply periodic minimal surface" - was the best way for the materials to mix at the microscopic scale. Triply periodic minimal surfaces arise in a number of situations, including self-assembly in block copolymers, nanocomposites, micellar materials and lipid-water systems.
According to Torquato, studying these non-intuitive shapes may offer insights into the relation between structure and function in both biological and man-made materials. "These results and the shapes we found suggest that there are incredibly rich opportunities that have not even been tapped into," he added. And such calculations may help materials scientists to design self-assembling materials with optimum properties.
The scientists reported their work in Physical Review Letters.