Multi-shape active composites by 3D printing of digital shape memory polymers

Area of Science:

• Materials Science and Engineering
• Additive Manufacturing
• Polymer Science

Background:

• 3D printing technology has advanced to create active structures capable of shape change post-fabrication.
• This evolving field, known as 4D printing, utilizes smart materials to enable dynamic transformations.
• Shape memory polymers (SMPs) are key materials enabling programmable shape recovery.

Purpose of the Study:

• To demonstrate the design and manufacture of active composites capable of multiple shape changes.
• To utilize digital shape memory polymers (SMPs) with varying glass transition temperatures (Tg) for controlled transformations.
• To develop a theoretical model for predicting and aiding the design of these 4D printed structures.

Main Methods:

• 3D printing of layered composite structures incorporating multiple families of SMP fibers with distinct Tgs.
• A single-step thermomechanical programming process to activate sequential shape transformations.
• Tuning fiber volume fraction to control bending deformation and developing a predictive theoretical model.

Main Results:

• Successfully fabricated 3D printed composite structures exhibiting temperature-dependent multi-shape transformations.
• Demonstrated sequential activation of SMP fiber families to induce controlled bending upon heating.
• Designed and printed flat 2D structures capable of self-folding and unfolding in response to thermal stimuli.

Conclusions:

• The developed 3D printed SMP composites offer a facile fabrication process for controllable multi-shape memory effects.
• These materials show significant potential for diverse 4D printing applications requiring programmable shape changes.
• The theoretical model aids in understanding and designing complex deformations in 4D printed structures.