Rheological formulation of room temperature vulcanizing silicone elastomer ink for extrusion-based 3D printing at room temperature

Silicone elastomer is a versatile material that is widely used in various industries due to its exceptional properties such as resistance to extreme temperatures, thermal conductivity, and bioinert. However, conventional fabrication methods of silicone are limited by molding which has design restrictions and makes it unsuitable for highly customized applications. This study presents a novel room temperature vulcanizing (RTV) silicone formulation that enables three-dimensional printing using an extrusion-based method. The study identifies that rheological measurements such as static yield stress are critical in determining the success of 3D silicone printing. Chemical additives, including nano-silica and plasticizers, have a significant impact on the static yield stress of the silicone ink, enabling the printing of complex structures. By adding 7 wt% of nano-silica and 10 wt% of plasticizers, a static yield stress of 400 Pa was achieved, which allowed the printing of complex 3D structures, including supportless macro-porous scaffolds. The newly formulated silicone ink demonstrated printability and the ability to achieve complex structures, reducing fabrication time, improving scalability, and allowing flexibility in the scaffold's design and specifications. This novel approach opens up new possibilities for the development of highly customized and cost-effective silicone-based 3D printing ink for the fabrication of complex silicone articles and macro-porous scaffolds. The potential applications of this approach include tissue engineering and biomedical devices.