LLNL researchers discover 3D cushions in shoe & helmet

Lawrence Livermore National Laboratory researchers (from left) Ward Small, Amanda Wu and Taylor Bryson have successfully 3D printed composite silicone materials that are flexible, stretchable and possess shape memory behavior, a discovery that could be used to create form-fitting cushioning activated by body heat. Photo by Carrie Martin/LLNL

Lawrence Livermore National Laboratory (LLNL) researchers have successfully 3D printed composite silicone materials that are flexible, stretchable and possess shape memory behavior, a discovery that could be used to create form-fitting cushioning activated by body heat, such as in a helmet or shoe.

The key to the shape memory behavior is the polymer micro-balloons that are embedded in the silicone ink. The thin polymeric shell in the micro-balloon has a glass transition temperature; below that temperature, the shell is rigid and glassy and above the temperature, the shell becomes soft and malleable.

The researchers printed their samples using a direct-ink writing process, where the composite ink material was extruded at room temperature from the printer’s nozzle to form woodpile-like structures with controlled porosity and architecture.

Lab researchers have filed a patent application for the material. Because it can be 3D printed into an arbitrary net shape and made into a highly porous structure with both open and closed cells, researchers said it might be useful for thermally activated cushioning that is highly tunable and customizable.