In the near future, 3D printing is predicted to revolutionize the production process, exceeding mass production and economy of scale, and thus our life. Nevertheless, the most of the people still see it as a way for having fun or, in the best case, as a technology for niche applications. One of the main reasons that still prevents the complete development of 3D printing is the relative limited number of printable materials, which restricts the available applications fields. In particular in light-based 3D printing technologies, such as SLA and DLP, the few available materials limit the use of these technologies to rapid prototyping, jewelry, hobby and few others. A common DLP/SLA printable formulation is composed of 3 main ingredients: the monomers, the photoitiator and a dye. The most common approach for increasing the materials‘ properties consists in playing with the monomers/oligomers or adding fillers. However, other strategies could be undertaken for widening the palette of functional printable materials. Here we present how an engineered use of the dye in the printable formulation, which is commonly used for limiting light penetration and thus for improving the printing precision, could be employed for imparting new functional properties to the printed object. Some examples will be presented: the first one concerns the use of azo-based dyes added to the printable formulation for the production of light responsive materials. Azobenzenes are a well-known class of photochromic chemical species,i.e. molecules able to undergo reversible transformation between two isomers with specific absorption spectra. By adding them to a printable formulation, after the production of the 3D object, it is possible to induce a stiffening or softening effect under laser irradiation depending on the state of the matrix. Such molecules allow as well to have a light-controlled gas permeability in 3D printed structures. In a second example a photoluminescent dye is used for the production of 3D printed photoluminescent waveguides and sensors. These few examples are just a hint for showing how the dyes, that usually are added just to give a final color to the printed object, could actively play a role in the formulations beyond their classical use, enabling new properties to the functional materials. This approach could help in easily developing 3D printable materials for different applications, moving towards a world in which 3D printing could have a role in everyday life.

Dyes in DLP formulations: Beyond the precision

2019 Spring National Meeting

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