Starch embedded hydrogels: Linking macroscopic mechanical properties with microscopic particle configurations

When noodles are made, a flour dough can be stretched to an extremely long length without breaking. What can we learn from it in order to synthesize innovative hydrogels? Mimicking the microstructure of flour dough, we synthesized a hybrid hydrogel by embedding wheat starch granules in an alginate-PAA gel network. This hybrid hydrogel shows many amazing mechanical properties, such as substantially improved stiffness and toughness, extremely high stretchability (up to 8000% strain), and persistent memory that is rewritable with training. With the help of x-ray microtomography, we found direct links between the macroscopic stress-strain curves and the microscopic particle structures when such hybrid hydrogels are deformed under uniaxial extension. This quasi-mimetic process allows us to not only produce materials with novel properties, but also explore new physics with simple, highly controlled systems.