Wallenberg Wood Science Center , Kemigården 4, 41296 Gothenburg, Sweden.
Department of Chemistry and Chemical Engineering, Chalmers University of Technology , Kemigården 4, 41296 Gothenburg, Sweden.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):40878-40886. doi: 10.1021/acsami.7b13400. Epub 2017 Nov 7.
This paper presents a sustainable all-wood-based ink which can be used for 3D printing of constructs for a large variety of applications such as clothes, furniture, electronics, and health care products with a customized design and versatile gel properties. The 3D printing technologies where the material is dispensed in the form of liquids, so called inks, have proven suitable for 3D printing dispersions of cellulose nanofibrils (CNFs) because of their unique shear thinning properties. In this study, novel inks were developed with a biomimetic approach where the structural properties of cellulose and the cross-linking function of hemicelluloses that are found in the plant cell wall were utilized. The CNF was mixed with xylan, a hemicellulose extracted from spruce, to introduce cross-linking properties which are essential for the final stability of the printed ink. For xylan to be cross-linkable, it was functionalized with tyramine at different degrees. Evaluation of different ink compositions by rheology measurements and 3D printing tests showed that the degree of tyramine substitution and the ratio of CNFs to xylan-tyramine in the prepared inks influenced the printability and cross-linking density. Both two-layered gridded structures and more complex 3D constructs were printed. Similarly to conventional composites, the interactions between the components and their miscibility are important for the stability of the printed and cross-linked ink. Thus, the influence of tyramine on the adsorption of xylan to cellulose was studied with a quartz crystal microbalance to verify that the functionalization had little influence on xylan's adsorption to cellulose. Utilizing xylan-tyramine in the CNF dispersions resulted in all-wood-based inks which after 3D printing can be cross-linked to form freestanding gels while at the same time, the excellent printing properties of CNFs remain intact.
本文提出了一种可持续的全木质基墨水，可用于各种应用的构建物的 3D 打印，例如具有定制设计和多功能凝胶特性的衣服、家具、电子产品和医疗保健产品。在 3D 打印技术中，材料以液体形式分配，即所谓的墨水，由于其独特的剪切变稀特性，已被证明适用于纤维素纳米纤维 (CNF) 的分散体 3D 打印。在这项研究中，采用仿生方法开发了新型墨水，利用了纤维素的结构特性和植物细胞壁中存在的半纤维素的交联功能。将 CNF 与木聚糖混合，木聚糖是从云杉中提取的一种半纤维素，引入交联特性是打印墨水最终稳定性所必需的。为了使木聚糖能够交联，它被不同程度的酪胺官能化。通过流变学测量和 3D 打印测试评估不同的墨水成分表明，酪胺取代度和 CNF 与木聚糖-酪胺在制备墨水中的比例影响了可印刷性和交联密度。打印了两层网格结构和更复杂的 3D 结构。与传统复合材料一样，组件之间的相互作用及其混溶性对于打印和交联墨水的稳定性很重要。因此，使用石英晶体微天平研究了酪胺对木聚糖向纤维素吸附的影响，以验证官能化对木聚糖向纤维素吸附的影响很小。在 CNF 分散体中使用木聚糖-酪胺可得到全木质基墨水，3D 打印后可交联形成独立的凝胶，同时保持 CNF 出色的打印性能。
