Solvent-triggered shape change in gradient-based 4D printed bilayers: case study on semi-crystalline polymer...

Area of Science:

• Polymer Science
• Materials Science
• Additive Manufacturing

Background:

• 4D printing enables dynamic shape changes in materials.
• Gradient structures in polymers can lead to anisotropic responses.
• Controlling swelling behavior is key for programmed material deformation.

Purpose of the Study:

• To present a novel 4D printing approach for creating solvent-triggered, gradient-based polymer bilayers.
• To demonstrate how crosslinking gradients induce differential swelling for controlled bending.
• To validate the shape transformation using a theoretical beam model.

Main Methods:

• Utilizing 4D printing to fabricate bilayers with controlled crosslinking gradients.
• Employing semi-crystalline crosslinked polymer networks.
• Immersion in a solvent to trigger out-of-plane bending.
• Applying and validating a beam model for shape transformation analysis.

Main Results:

• Successful 4D printing of gradient-based polymer bilayers.
• Achieved programmed out-of-plane bending upon solvent exposure.
• Demonstrated that differential swelling due to crosslinking gradients drives the bending.
• Experimental results validated by the beam model predictions.

Conclusions:

• The proposed 4D printing approach effectively creates solvent-responsive bending structures.
• Crosslinking gradients are a viable strategy for programming shape transformations in polymers.
• The validated beam model provides a predictive tool for designing such 4D printed materials.