Three-dimensional (3D) printing is used to fabricate tissue scaffolds. Polymer chains in these objects are typically unoriented. The mechanical properties of these scaffolds can be significantly enhanced by proper alignment of polymer chains. However, post-processing routes to increase orientation can be limited by the geometry of the printed object. Here, we show that it is possible to orient polymer chains during printing by optimizing printing parameters to take advantage of the flow characteristics of the polymer. This is demonstrated by printing a polymeric scaffold for meniscus regeneration using poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate), poly(DTD DD). Alignment of polymer chains was achieved by translating the printhead at sufficiently high speeds when the polymer was still in a semi-solid state as it cooled from the fluid state at the tip of the nozzle using a critical combination of nozzle diameter, extrusion pressure, and temperature. The degree of orientation as evaluated by x-ray diffraction and thermal shrinkage, was greater than that of drawn fibers. Significant orientation and defect-free printing was achieved even for scaffolds with complex geometries. The ability to orient polymers during 3D printing has the potential to combine the advantages of 3D printing with the superior mechanical performance of more conventional polymer processing methods, such as drawing.

中文翻译：

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在热挤压 3D 打印物体中实现分子取向。

三维（3D）打印用于制造组织支架。这些物体中的聚合物链通常是无取向的。通过聚合物链的适当排列可以显着增强这些支架的机械性能。然而，增加方向的后处理路线可能会受到打印物体的几何形状的限制。在这里，我们表明，通过优化打印参数以利用聚合物的流动特性，可以在打印过程中定向聚合物链。这是通过使用聚（脱氨基酪氨酰-酪氨酸十二烷基十二烷二酸酯）、聚（DTD DD）打印用于半月板再生的聚合物支架来证明的。聚合物链的排列是通过以足够高的速度平移打印头来实现的，此时聚合物仍处于半固态，因为它在喷嘴尖端从流体状态冷却，使用喷嘴直径、挤出压力和温度的关键组合。温度。通过X射线衍射和热收缩评价的取向度大于拉伸纤维的取向度。即使对于具有复杂几何形状的支架，也能实现显着的定向和无缺陷打印。在 3D 打印过程中定向聚合物的能力有可能将 3D 打印的优点与更传统的聚合物加工方法（例如拉伸）的卓越机械性能结合起来。