Symmetry breaking in living systems is often achieved by coupling of chemical reactions and selective growth to achieve shape change. In many systems, however, it is becoming more recognized that the underlying materials themselves can cause the symmetry breaking. It is important to understand such mechanisms as they could help us direct growth, shape change, and adaptability in artificial systems.

Materials exhibiting one time (static) or dynamic shape-change behaviour, are useful for developing novel artificial muscles, adaptable structures, and for bringing insights into the processes or morphogenesis. They have also shown much promise for engineering multi-functional materials.

We show examples of engineering the symmetry breaking and dynamics for multiple structures and processes, on multiple lengthscales – from nanometers to centimeters. We demonstrate the formation of Janus and other asymmetric particles, which form as a result of coupling of chemical reactions to non-linear mechanical properties of materials[1]. We also demonstrate the opposite effects – how mechanical deformations and molecular interactions can help one simplify chemical syntheses[2].Further, we also demonstrate that even without reactions, the material properties and geometry alone could cause symmetry breaking. By bending a spherical cap and a cone shell, we characterize the instabilities and show novel behaviors, both static and dynamic.

Upon inversion of the magnetic spherical cap, for example, using high speed video, we have captured an intermediate asymmetric quasi-stable state. The results are reproduced faithfully by a finite element model analysis where we only put in the material properties and the remote forces exerted on the cap by a magnetic field[3]. Equilibrium deformations also show symmetry breaking. We have focused on another simple shape – a conical shell. Upon deformation one can achieve in a controlled way symmetry breaking with 2-, 3-, 4- and 5- sided polygonal shapes. We explore the energetics of these transitions, the underlying materials properties which control them, and the dimensionless scaling that could help us predict them for various cones.