Purpose

The purpose of this paper is to demonstrate an innovative, fast and low-cost method to fabricate customized stents using polyurethane-based shape memory polymers composite reinforced by cellulose nanocrystal (CNC), achieved by a commercial desktop extrusion-based additive manufacturing (EBAM) device.

Design/methodology/approach

The composite filament for printing the stents was prepared by a two-step melt-compounding extrusion process. Afterward, the stents were produced by a desktop EBAM printer. Thermal characterizations, including thermo-gravimetric analysis (TGA) and modulated differential scanning calorimetry (modulated DSC), were conducted on stent samples and filament samples, respectively. Then the stents were programmed under 45°C. Recovery characterizations, including recovery force and recovery ratio measurement, were conducted under 40°C.

Findings

TGA results showed that the materials were stable under the printing temperature. Modulated DSC results indicated that, with the addition of CNCs, the glass transition temperature of the material dropped slightly from 39.7°C at 0 Wt.% CNC to 34.2°C at 7 Wt.% CNC. The recovery characterization showed that the stents can exert a maximum recovery force of 0.4 N/mm when 7 Wt.% of CNCs were added and the maximum recovery ratio of 35.8% ± 5.1% was found when 4 Wt.% of CNCs were added. The addition of CNC improved both the recovery ratio and the recovery force of the as-prepared stents.

Originality/value

In terms of recovery force, the as-prepared stents out-performed commercially available stents by 30 times. In addition, additive manufacturing offers more flexibility in the design and fabrication of customized cardiovascular stents.

中文翻译：

---

纤维素纳米晶体增强形状记忆聚合物心血管支架

目的

本文的目的是演示一种创新，快速且低成本的方法，该方法使用由纤维素纳米晶体（CNC）增强的聚氨酯基形状记忆聚合物复合材料来制造定制支架，该方法是通过商用台式挤压基增材制造（EBAM）实现的设备。

设计/方法/方法

通过两步熔融复合挤出工艺制备用于印刷支架的复合长丝。之后，支架由台式EBAM打印机生产。分别对支架样品和细丝样品进行了热表征，包括热重分析（TGA）和调制差示扫描量热法（调制DSC）。然后将支架在45°C下编程。在40℃下进行包括恢复力和恢复比测量在内的恢复特性。

发现

TGA结果表明该材料在印刷温度下是稳定的。调制的DSC结果表明，添加CNC控制器后，材料的玻璃化转变温度从0 Wt。％CNC时的39.7°C略降至7 Wt。％CNC时的34.2°C。恢复特性表明，当添加7 Wt。％的CNC时，支架可发挥最大的恢复力0.4 N / mm，当添加4 Wt。％的CNC时，支架的最大恢复率达到35.8％±5.1％。添加CNC改善了所制备支架的恢复率和恢复力。

创意/价值

就恢复力而言，所制备的支架性能比市售支架高出30倍。此外，增材制造为定制心血管支架的设计和制造提供了更大的灵活性。