Princeton University engineers have developed a new 3D printing technique for producing soft, stretchy plastics with customizable properties. The method, detailed in Advanced Functional Materials, uses low-cost thermoplastic elastomers that cost approximately one cent per gram. The resulting materials can be both flexible and rigid in specific directions, while maintaining recyclability.
The technique relies on controlling nanoscale structures within the material during the printing process. The researchers utilized block copolymers that form stiff cylindrical structures measuring 5-7 nanometers in thickness, embedded within a flexible polymer matrix. These structures can be oriented during printing to create materials with varying degrees of stiffness and flexibility in different directions.
A key feature of the process is thermal annealing, which involves controlled heating and cooling of the printed material. “I think one of the coolest parts of this technique is the many roles that thermal annealing plays— it both drastically improves the properties after printing, and it allows the things we print to be reusable many times and even self-heal if the item gets damaged or broken,” said Alice Fergerson, the study’s lead author.
The research team demonstrated the versatility of their technique by creating various structures, including a small vase and printed text. They also successfully incorporated functional additives, such as light-responsive molecules, without compromising the material’s mechanical properties. The team verified the material’s self-healing capabilities by cutting and rejoining samples through annealing, with the repaired materials showing properties similar to the originals.
The technology shows promise for various applications, including soft robotics, medical devices, prosthetics, protective equipment, and customized shoe soles. The research team plans to explore new architectures suitable for wearable electronics and biomedical devices in their future work.
Source: engineering.princeton.edu
