Reduction of amylose/amylopectin ratio improves the molecular orientation and performance of three-dimensional-printed thermoplastic starch/polylactic acid intestinal stents

Three-dimensional (3D)-printed intestinal stents based on thermoplastic starch (TPS)/polylactic acid (PLA) are a promising biodegradable alternative to conventional metal stents. However, the influence of the structure and conformation of starch on the properties of 3D-printed TPS/PLA intestinal stents requires clarification. This study evaluated the effects of the amylose/amylopectin ratio of starch on the molecular orientation, molecular interactions, crystallization behavior, microstructure, and thermodynamic, mechanical and hydrolysis performance of 3D-printed TPS/PLA intestinal stents. The molecular orientation of starch was determined during the preparation of the filaments for 3D printing. The 3D printing process promoted intermolecular interactions by further improving the molecular orientation, and enhanced the short-range order and crystallinity of the starch molecules. Decreasing the amylose/amylopectin ratio enhanced the short-range order of the starch molecules by increasing molecular orientation, which improved the circumferential compression performance of the 3D-printed intestinal stents but not the axial compression performance. However, the reduction in plasticized starch particles and improved PLA continuity caused by decreasing the amylose/amylopectin ratio contributed to improving the circumferential and axial compression performance as well as the anti-hydrolysis performance. These findings highlight the potential of starch to replace PLA as an inexpensive raw material for the development of high-performance biodegradable 3D-printed intestinal stents.