Domain Formations and Pattern Transitions via Instabilities in Soft Heterogeneous Materials. 
Experimental observations of domain formations and pattern transitions in soft particulate composites under large deformations are reported herein.  The system of stiff inclusions periodically distributed in a soft elastomeric matrix experiences dramatic microstructure changes upon the development of elastic instabilities.  In the experiments, the formation of microstructures with antisymmetric domains and their geometrically tailored evolution into a variety of patterns of cooperative particle rearrangements are observed.  Through experimental and numerical analyses, it is shown that these patterns can be tailored by tuning the initial microstructural periodicity and concentration of the inclusions.  Thus, these fully determined new patterns can be achieved by fine tuning of the initial microstructure.