Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, Royal School of Mines , Prince Consort Road, South Kensington, London SW7 2BP, U.K.
Materials Innovation Factory & School of Engineering, University of Liverpool , Harrison Hughes Building, Brownlow Hill, Liverpool L69 3GH, U.K.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):32977-32989. doi: 10.1021/acsami.7b07717. Epub 2017 Sep 12.
Many 3D printing technologies are based on the development of inks and pastes to build objects through droplet or filament deposition (the latter also known as continuous extrusion, robocasting, or direct ink writing). Controlling and tuning rheological behavior is key for successful manufacturing using these techniques. Different formulations have been proposed, but the search continues for approaches that are clean, flexible, robust and that can be adapted to a wide range of materials. Here, we show how graphene oxide (GO) enables the formulation of water-based pastes to print a wide variety of materials (polymers, ceramics, and steel) using robocasting. This work combines flow and oscillatory rheology to provide further insights into the rheological behavior of suspensions combining GO with other materials. Graphene oxide can be used to manipulate the viscoelastic response, enabling the formulation of pastes with excellent printing behavior that combine shear thinning flow and a fast recovery of their elastic properties. These inks do not contain other additives, only GO and the material of interest. As a proof of concept, we demonstrate the 3D printing of additive-free graphene oxide structures as well as polymers, ceramics, and steel. Due to its amphiphilic nature and 2D structure, graphene oxide plays multiple roles, behaving as a dispersant, viscosifier, and binder. It stabilizes suspensions of different powders, modifies the flow and viscoelasticity of materials with different chemistries, particle sizes and shapes, and binds the particles together, providing green strength for manual handling. This approach enables printing complex 3D ceramic structures using robocasting with similar properties to alternative formulations, thus demonstrating the potential of using 2D colloids in materials manufacturing.
许多 3D 打印技术都是基于开发油墨和糊剂来通过液滴或长丝沉积（后者也称为连续挤压、机器人铸造或直接喷墨打印）来构建物体。控制和调整流变行为对于使用这些技术成功制造是至关重要的。已经提出了不同的配方，但仍在寻找清洁、灵活、稳健的方法，并且可以适应广泛的材料。在这里，我们展示了氧化石墨烯 (GO) 如何使水基糊剂能够使用机器人铸造打印各种材料（聚合物、陶瓷和钢）。这项工作结合了流动和振荡流变学，为结合 GO 与其他材料的悬浮液的流变行为提供了更深入的了解。氧化石墨烯可用于操纵粘弹性响应，使具有出色打印性能的糊剂能够形成，其具有剪切稀化流动和快速恢复弹性特性的结合。这些油墨不含其他添加剂，仅含 GO 和感兴趣的材料。作为概念验证，我们展示了无添加剂氧化石墨烯结构以及聚合物、陶瓷和钢的 3D 打印。由于其双亲性质和 2D 结构，氧化石墨烯发挥多种作用，表现为分散剂、增稠剂和粘合剂。它稳定了不同粉末的悬浮液，改变了具有不同化学性质、粒径和形状的材料的流动和粘弹性，并将颗粒结合在一起，为手动处理提供绿色强度。这种方法能够使用机器人铸造打印具有类似性能的复杂 3D 陶瓷结构，替代配方，从而展示了二维胶体在材料制造中的应用潜力。
