Joas Sebastian, Tovar Günter E M, Celik Oguz, Bonten Christian, Southan Alexander
Institute of Interfacial Process Engineering and Plasma Technology IGVP, University of Stuttgart, Nobelstr. 12, 70569 Stuttgart, Germany.
Institut für Kunststofftechnik IKT, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany.
Gels. 2018 Aug 14;4(3):69. doi: 10.3390/gels4030069.
Hydrogels are an interesting class of materials used in extrusion-based 3D printing, e.g., for drug delivery or tissue engineering. However, new hydrogel formulations for 3D printing as well as a detailed understanding of crucial formulation properties for 3D printing are needed. In this contribution, hydrogels based on poly(ethylene glycol) diacrylate (PEG-DA) and the charged monomers 3-sulfopropyl acrylate and [2-(acryloyloxy)ethyl]trimethylammonium chloride are formulated for 3D printing, together with Poloxamer 407 (P407). Chemical curing of formulations with PEG-DA and up to 5% () of the charged monomers was possible without difficulty. Through careful examination of the rheological properties of the non-cured formulations, it was found that flow properties of formulations with a high P407 concentration of 22.5% () possessed yield stresses well above 100 Pa together with pronounced shear thinning behavior. Thus, those formulations could be processed by 3D printing, as demonstrated by the generation of pyramidal objects. Modelling of the flow profile during 3D printing suggests that a plug-like laminar flow is prevalent inside the printer capillary. Under such circumstances, fast recovery of a high vicosity after material deposition might not be necessary to guarantee shape fidelity because the majority of the 3D printed volume does not face any relevant shear stress during printing.
水凝胶是用于基于挤出的3D打印的一类有趣的材料，例如用于药物递送或组织工程。然而，需要用于3D打印的新型水凝胶配方以及对3D打印关键配方特性的详细了解。在本论文中，基于聚（乙二醇）二丙烯酸酯（PEG-DA）以及带电单体3-磺丙基丙烯酸酯和[2-（丙烯酰氧基）乙基]三甲基氯化铵，并与泊洛沙姆407（P407）一起，配制了用于3D打印的水凝胶。用PEG-DA和高达5%（）的带电单体对配方进行化学固化并不困难。通过仔细研究未固化配方的流变特性，发现P407浓度为22.5%（）的高浓度配方的流动特性具有远高于100 Pa的屈服应力以及明显的剪切变稀行为。因此，如通过生成金字塔形物体所证明的，那些配方可以通过3D打印进行加工。3D打印过程中流动剖面的建模表明，打印机毛细管内部普遍存在类似柱塞的层流。在这种情况下，材料沉积后高粘度的快速恢复可能不是保证形状保真度所必需的，因为大多数3D打印体积在打印过程中不会面临任何相关的剪切应力。
