Co-continuous structure enhanced magnetic responsive shape memory PLLA/TPU blend fabricated by 4D printing

ABSTRACT

Combining poly (L-lactic acid) (PLLA) with thermoplastic polyurethane elastomer (TPU) can integrate the advantages of excellent biocompatibility and intrinsic shape memory ability of PLLA and high elasticity and excellent shape memory properties of TPU in the application of minimally invasive surgery for bone tissue engineering. However, TPU easily forms a sea-island-like structure in PLLA matrix, decreasing shape memory properties. In this study, a co-continuous structure of TPU phase in PLLA matrix was constructed by adding Fe₃O₄ nanoparticles due to the changed interfacial tension and flow behavior of TPU, which endowed the TPU/PLLA/Fe₃O₄ blend fabricated via selective laser sintering (SLS) with excellent shape memory properties. As a result, the morphology of TPU in the blend changed from sea-island-like structure to complete co-continuous structure with increasing Fe₃O₄ content (0 to 10wt%), and shape recovery ratios in 50 °C water increased from 66.67 to 95.92%. The introduction of Fe₃O₄ endowed the blend with magnetic responsive shape memory in alternating magnetic field because Fe₃O₄ could heat it by generating heat from relative friction and particle collisions. Besides, the tensile modulus and hardness of the specimen with 10wt% Fe₃O₄ nanoparticles increased. In addition, the blend demonstrated excellent biocompatibility by promoting cell adhesion, spreading, and proliferation.

KEYWORDS:

• Shape memory
• magnetic
• PLLA/TPU blend
• co-continuous

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the following funds: (1) The Natural Science Foundation of China (52275393, 51935014, 82072084); (2) Hunan Provincial Natural Science Foundation of China (2021JJ20061, 2020JJ3047, 2019JJ50588); (3) Jiangxi Provincial Natural Science Foundation of China (20224ACB204013); (4) Technology Innovation Platform Project of Shenzhen Institute of Information Technology 2020 (PT2020E002); (5) Guangdong Province Precision Manufacturing and Intelligent production education Integration Innovation Platform (2022CJPT019).