Autonomous Off-Equilibrium Morphing Pathways of a Supramolecular Shape-Memory Polymer

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Synthetic shape-shifting materials typically exhibit limited morphing pathways, unlike biological systems.
• Shape-memory polymers (SMPs) usually require external stimuli for shape recovery along a fixed route.

Purpose of the Study:

• To design a covalently crosslinked SMP with ureidopyrimidinone (UPy) supramolecular moieties for autonomous, programmable shape-shifting.
• To explore the time-temperature dependency of UPy units for spatio-temporal control of morphing pathways.
• To demonstrate versatile applications using an off-equilibrium mechanism with digitally controlled photothermal heating.

Main Methods:

• Incorporation of abundant ureidopyrimidinone (UPy) supramolecular moieties into a covalently crosslinked polymer network.
• Utilizing digitally controlled photothermal heating for precise, off-equilibrium control of shape transformation.
• Leveraging the glass transition temperature for temporal locking and unlocking of material shape.

Main Results:

• Demonstrated multi-shape-transformation capabilities in the designed SMP.
• Developed an "invisible"-color-based clock and a time-temperature indicator using the material's properties.
• Showcased sequence-programmable 4D printing enabled by the autonomous shape-shifting mechanism.

Conclusions:

• The developed SMP offers unprecedented control over shape-shifting pathways through time-temperature dependent mechanisms.
• The UPy-functionalized SMP enables autonomous, programmable transformations for advanced material applications.
• This work paves the way for sophisticated 4D printing and smart material systems.