Thermo-Mechanical Characterization of 4D-Printed Biodegradable Shape-Memory Scaffolds Using Four-Axis 3D-Printing...

Area of Science:

• Biomaterials Engineering
• Polymer Science
• Additive Manufacturing

Background:

• Biodegradable shape-memory polymers (SMPs) are crucial for tissue engineering scaffolds.
• Traditional fused deposition modeling (FDM)/material extrusion (MEX) methods have limitations in achieving high-quality surfaces and mechanical properties for complex structures.
• Developing advanced 3D/4D printing techniques is essential for fabricating functional biodegradable vascular stents (BVS).

Purpose of the Study:

• To compare the efficacy of a standard FDM/MEX printing technique with a novel four-axis printing method for biodegradable SMP scaffolds.
• To evaluate the impact of the four-axis printing method on surface quality, mechanical properties, and shape-memory effect of 4D-printed biodegradable vascular stents (BVS).
• To assess the shape recovery performance of SMP scaffolds fabricated using the novel printing technique.

Main Methods:

• Utilized a standard FDM/MEX printer and a modified four-axis printer with poly lactic acid (PLA) as the printing material.
• Fabricated biodegradable vascular stent (BVS) models using both printing techniques.
• Conducted tensile testing to evaluate mechanical properties, specifically elongation at break.
• Performed thermomechanical programming and subsequent heating (in-chamber and warm bath) to assess shape recovery.

Main Results:

• The four-axis printing method resulted in significantly improved surface quality compared to standard printing.
• Tensile testing revealed a doubling in elongation at break for four-axis printed specimens (8.15 mm) versus standard printed specimens (3.92 mm).
• SMP scaffolds exhibited an average shape recovery of 99.7% after thermomechanical programming, with warm-bath heating (~3 s) being faster than in-chamber heating (120 s).

Conclusions:

• The novel four-axis 4D printing technique is a promising method for fabricating high-quality biodegradable SMP structures.
• This advanced printing approach enhances mechanical properties and shape-memory recovery, making it suitable for future applications like biodegradable vascular stents (BVS).
• The study demonstrates the potential of tailored additive manufacturing for creating advanced biomedical devices.