Fused Deposition Modeling and Characterization of Heat Shape Memory Poly(lactic) Acid-Based Porous Vascular Scaffold

Li Zhang; Muhammad Hanif; Jiacheng Li; Abdul Hakim Shah; Wajid Hussain; Guotao Zhang

doi:10.3390/polym15020390

Fused Deposition Modeling and Characterization of Heat Shape Memory Poly(lactic) Acid-Based Porous Vascular Scaffold

Polymers (Basel). 2023 Jan 11;15(2):390. doi: 10.3390/polym15020390.

Authors

Li Zhang¹, Muhammad Hanif¹, Jiacheng Li¹, Abdul Hakim Shah², Wajid Hussain³, Guotao Zhang¹

Affiliations

¹ Faculty of Mechanical Design and Vehicle Engineering, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
² Department of Physics, Khushal Khan Khattak University, Karak 27200, Pakistan.
³ Advanced Biomaterials and Tissue Engineering Centre, School of Biomedical Engineering, College of Life Sciences and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.

Abstract

Shape memory polymers have received widespread attention from researchers because of their low density, shape variety, responsiveness to the environment, and transparency. This study deals with heat-shape memory polymers (SMPs) based on polylactic acid (PLA) for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis. The solid isotropic material penalization method (SIMP) was applied to optimize the vascular scaffolds. Based on the torsional torque loading of Hyperworks Optistruct and the boundary conditions, the topological optimization model of a vascular scaffold unit was established. Forward and reverse hybrid modeling technology was applied to complete the final stent structure's assembly. The glass transition temperature for the present SMPs is 42.15 °C. With the increase in temperature, the ultimate tensile strength of the SMPs is reduced from 29.5 MPa to 11.6 MPa. The maximum modulus at room temperature was around 34 MPa. Stress relaxation curves show that the material classification is a "thermoset" polymer. The superb mechanical properties, the transition temperature of the SMPs, and the recovery ratio made it a feasible candidate for a vascular scaffold. A circular tube based on the shape memory polymers was presented as an example for analyzing the recovery ratio in an unfolding state. A higher recovery ratio was obtained at a temperature of 65 °C with a tube thickness of 2 mm. Finally, the proposed porous vascular scaffold was successfully fabricated, assessed, and compared with the original and previously developed vascular scaffolds. The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. The tensile strength, Young's modulus, and bending strength of the proposed scaffold were 29.5 MPa, 695.4 MPa, and 6.02 MPa, respectively. The results showed that the proposed scaffold could be regarded as a potential candidate for a vascular implantation.

Keywords: mechanical properties; shape memory polymers; solid isotropic material penalization method (SIMP); thermodynamic properties; vascular scaffolds.

Grants and funding

This work was financially supported by the National Key R&D Program of China with project entitled, “Research on loading-thermal control mechanism and design constraint mechanism of tube, plate and rod lattice structure based on SLM additive manufacturing process.” (Funding Number: 2022YFB3707001).