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.