Arresting Spinodal-like Structures in Elastic Matrices

Phase separation is a fascinating physical process that is not only responsible for the internal organization of living cells but also a powerful tool for engineering the structure of functional materials. Nature has evolved the ability to control phase separation to make composite materials with an exquisite range of optical and mechanical properties. In this work, we demonstrate control over spinodal decomposition processes at the microscale using polymer matrices. We demonstrate that the length scale of our resulting bicontinous structures is tuneable and controlled by the mechanical properties of the matrix. We also show that the threshold for phase separation is stabilized with increasing elasticity, and that the preferred demixing pathway is spinodal decomposition for stiff samples. These results open up a range of possibilities for both fundamental and applied research, including the development of polymer composites with structural colour.