Georgian Technical University Different Transparencies Colors Shown In 3-D Printed Nanomaterial.

Metallic nanoparticles have been used as glass colorants since the Roman Empire (The Roman Empire was the post-Roman Republic period of the ancient Roman civilization. It had a government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, North Africa, and West Asia). One of the most famous pieces of pottery from the period is the Lycurgus cup (The Lycurgus Cup is a 4th-century Roman glass cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it; red when lit from behind and green when lit from in front). The nanoparticles embedded in this cup have an optical peculiarity presenting different colors depending on the angle of the illumination. This effect is called dichroism. Now scientists from Georgian Technical University have made 3-D printed objects showing this dichroic effect. The researchers synthesized a special type of gold nanoparticle with different sizes. These nanoparticles were then embedded in a common 3-D printing material (PVA) (Poly is a water-soluble synthetic polymer. It has the idealized formula [CH₂CH]. It is used in papermaking, textiles, and a variety of coatings. It is white and odorless. It is sometimes supplied as beads or as solutions in water; Poly is an aliphatic rubbery synthetic polymer with the formula ₙ. It belongs to the polyvinyl esters family, with the general formula -[RCOOCHCH₂]-. It is a type of thermoplastic) used in standard, off-the-shelf 3-D printers. The amount of gold in the material is minute, a mere 0.07 weight percent. Such a small amount of gold doesn’t change the printability of the material which is the same as normal material. However even with this minimal amount of gold the nanocomposite material has a distinct dichroic effect showing a brown opaque color in reflection (when the illumination and the observer are on the same side) and a violet transparent color in transmission (when the illumination and the observer are on the opposite sides). This innovation opens the doors to a new class of 3-D printable nanomaterials with the intrinsic properties of the nano-world in this case optical properties which are retained even in a 3-D printed object. Such peculiar optical properties could be used by artists and applied in nanocomposite-based lenses and filters. The researchers are now working on improving this methodology using different nanoparticles and different materials.