Proceedings of Online Meetup: Nanocrystals in Additive Manufacturing (AdditiveNC)
Publication date: 3rd May 2020
Photo-polymerization is a widely used technology in various applications and areas, ranging from adhesives and coatings to the fabrication of complex and functional objects by 2D & 3D printing. Traditionally it involves organic photoinitiators that upon excitation in a narrow UV range breaks apart to produce reactive species that initiate a radical polymerization chain reaction. The available formulations are numerous and well established for specific applications. Yet, there is a need for new photoinitiators with better and/or distinctive capabilities. This is due to a combination of global trends and technological advances including a push towards a greener and safer processes and materials. Moreover, there is enhanced development of new applications, such as photocuring for dental care and 3D printing of smart drug capsules, that necessitate new materials and formulations.
Here we report on a new family of photoinitiators based on semiconductor nanocrystals, Quantum PI, which show unique advantages for water-based and solvent-free polymerization. Unlike conventional photoinitiators which work in a stoichiometric manner, our nanoparticles form radicals through a photocatalytic process. In particular, we demonstrate their use in 3D printing in water, where they simultaneously form hydroxyl radicals for the polymerization and consume dissolved oxygen which is a known retarder. We also demonstrate their potential for two-photon polymerization due to their giant two-photon absorption cross-section and as multifunctional agents.
The advantages of the quantum photoinitiators will introduce new environmentally friendly photo-curing approaches. Furthermore, their capacity to polymerize in water opens exciting opportunities in the biomedical arena, such as for printing of scaffolds for tissue engineering.
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