4D Printing of Composite Thermoplastic Elastomers for Super-Stretchable Soft Artificial Muscles

This study explores the development of soft, super-stretchable artificial muscles by 4D printing of composite thermoplastic elastomers. A propylene-based elastomer, combined with carbon black (CB) nanoparticles, is utilized to develop nanocomposite elastomers with enhanced mechanical properties. A pellet-based material extrusion technique is employed to overcome the challenges of filament buckling in traditional filament-based printing methods. The pure elastomer exhibits an elongation at break of 4048% and a tensile strength of 3.71 MPa, while the optimal nanocomposite (2% CB) achieves an elongation of 2665% and a tensile strength of 5.58 MPa. Scanning electron microscopy confirms that high-quality printing with well-bonded layers is achievable. The shape memory properties of printed elastomers are assessed through cyclic tests. It demonstrates the material's ability to recover its original shape after deformation with a drop in mechanical properties after each cycle controllable by CB reinforcements. Innovative artificial muscles are inspired by the chameleon's tongue, achieving significant strain recovery and lifting capabilities. Objects with varying weights are lifted by these muscles, showcasing potential for soft robotics and actuators. The potential of 4D printed composite elastomers in creating highly stretchable, efficient artificial muscles is highlighted, offering promising applications in fields requiring high elasticity and mechanical performance.