Ding Hui, Barg Suelen, Derby Brian
Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Nanoscale. 2020 Jun 7;12(21):11440-11447. doi: 10.1039/c9nr10831a. Epub 2020 May 21.
Conventional 3D printing of graphene requires either a complex formulation of the ink with large quantities of polymers or essential post-processing steps such as freeze drying to allow printability. Here we present a graphene capillary suspension (GCS) containing 16.67 wt% graphene nanoparticles in aqueous suspension with 3.97 wt% carboxymethyl cellulose (CMC) as a stabiliser and a small quantity of the immiscible liquid octanol. This is shown to have the appropriate rheological properties for 3D printing, which is demonstrated through the fabrication of a simple lattice structure by direct writing and air drying at room temperature. The printed structure has a porosity of 81%, is robust for handling with a compression strength of 1.3 MPa and has an electrical conductivity of 250 S m. After heat treatment at 350 °C conductivity is 2370 S m but the strength reduces to 0.4 MPa. X-Ray tomography of the internal architecture after printing shows the formation of the capillary suspension eliminates ordering of the 2D materials during extrusion through the printer nozzle. Thus capillary suspensions can be used to direct write graphene 3D structures without the necessity of complicated drying steps or burn-out of large quantities of polymer additions, facilitating shape retention and property control as compared to current 2D material ink formulations used for 3D printing.
传统的石墨烯3D打印需要使用大量聚合物对油墨进行复杂配方，或者采取诸如冷冻干燥等必要的后处理步骤来实现可打印性。在此，我们展示了一种石墨烯毛细管悬浮液（GCS），它是一种水悬浮液，含有16.67 wt%的石墨烯纳米颗粒，以3.97 wt%的羧甲基纤维素（CMC）作为稳定剂，并添加了少量不混溶的液体辛醇。结果表明，这种悬浮液具有适合3D打印的流变学特性，通过在室温下直接书写和空气干燥制备简单的晶格结构得到了验证。打印结构的孔隙率为81%，抗压强度为1.3 MPa，便于处理，电导率为250 S/m。在350°C进行热处理后，电导率为2370 S/m，但强度降至0.4 MPa。打印后内部结构的X射线断层扫描显示，毛细管悬浮液的形成消除了二维材料在通过打印机喷嘴挤出过程中的有序排列。因此，与目前用于3D打印的二维材料油墨配方相比，毛细管悬浮液可用于直接书写石墨烯三维结构，而无需复杂的干燥步骤或添加大量聚合物后再去除，有助于保持形状和控制性能。
