Printing with full highly detailed color is a goal for many a 3D printing company. This is especially true of SLS and SLA printing endeavors, as they use conventional carbon-based sensitizers. These often only come in black or grey and thus leave a lot more to desire. However, researchers at the Institute of Photonic Sciences (IFCO) have discovered that certain photosensitisers enable color SLS 3D printing.

“Photothermal sensitisers” have recently become more popular as means of improving polymer sintering. Similarly, researchers also add photosensitisers to further reduce the energy requirements of the process. We have known for a while that elements like carbon nanotubes, carbon black and graphene absorb light far better and can serve as catalysts to the process. However, now researchers are testing the field with photosensitisers like gold nanorods and producing white/”as close to white as possible” prints. This material can easily mix with dyes to produce resilient color prints.

Coating Materials with Photosensitisers

As the study states: “Here, we address this problem by designing resonant photothermal sensitizers made of plasmonic nanoparticles that strongly absorb in the near-infrared, while only minimally interacting with visible light.”

They created the new print materials by coating gold nanorods in silica and mixing them in with polyamide powders. They then worked out a way of mixing in dyes for the full technicolor experience. Aside from displaying the ability for vivid color, it was also immensely photosensitive. The researchers noted that the light-to-heat conversion compared with equivalent composites using the industry standard carbon black as a sensitiser. So much so, in fact, that they could sinter it with a low-power light source.

The existence of this method is a great step forward for SLS printing, in both color and photothermal sensitivity. All sorts of companies are exploring the ability to print in color across many types of 3D printing. This is, as many feel, one of the things stopping the adoption of additive manufacturing as a whole. Hopefully, this is a step forward into a bright and colorful future.

The full study, White and Brightly Colored 3D Printing Based on Resonant Photothermal Sensitizers, is available here. Featured image courtesy American Chemical Society.