Institute of Polymer Science and Engineering, National Taiwan University, No. 1, Sec. 4 Roosevelt Road, Taipei 10617, Taiwan, ROC.
Department of Chemical Engineering, National Chung Hsing University, No. 145, Xingda Road, Taichung 40227, Taiwan, ROC.
Carbohydr Polym. 2019 May 15;212:75-88. doi: 10.1016/j.carbpol.2019.02.025. Epub 2019 Feb 11.
Waterborne polyurethane (PU) is a green, high performance elastomer but the viscosity of the dispersion is generally too low for direct three-dimensional (3D) printing. Composite brings additional properties while reinforcing the substrate. In the study, printable PU composites were successfully prepared by introducing cellulose nanofibrils (CNFs) and the viscosity was effectively regulated by the amount of neutralizing agent during in-situ synthesis. Rheological measurements supported the good printability. TEM images revealed that CNFs linked multiple PU nanoparticles to form a 'skewer' structure. PU/CNF scaffolds were 3D-printed with excellent pattern fidelity and structure stability. Meanwhile, the compression modulus was much higher than the scaffolds printed with a water-soluble viscosity enhancer (PEO). Fibroblasts kept proliferating in the scaffolds for two weeks. The interaction between CNF and PU may offer a novel and unique way to tune the viscosity of waterborne PU for direct 3D printing and enhance the properties of the green elastomers.
水基型聚氨酯（PU）是一种绿色的高性能弹性体，但分散体的粘度通常太低，不适合直接进行三维（3D）打印。复合材料在增强基材的同时带来了额外的性能。在这项研究中，通过引入纤维素纳米纤维（CNF）成功制备了可打印的 PU 复合材料，并且通过原位合成过程中中和剂的用量有效地调节了粘度。流变学测量支持了良好的可打印性。TEM 图像显示，CNF 将多个 PU 纳米颗粒连接在一起形成了“串”结构。PU/CNF 支架具有出色的图案保真度和结构稳定性，并且 3D 打印。同时，压缩模量远高于用水溶性增粘剂（PEO）打印的支架。成纤维细胞在支架中持续增殖两周。CNF 和 PU 之间的相互作用可能为调节水基型 PU 的粘度以直接 3D 打印并增强绿色弹性体的性能提供了一种新颖而独特的方法。
