High-resolution 3D photopolymerization assisted by upconversion nanoparticles for rapid prototyping applications

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Three-dimensional (3D) printing relies on photopolymerization.
• Near-infrared (NIR) light offers advantages for deep tissue penetration and reduced scattering.
• Upconversion nanomaterials can convert NIR light to shorter wavelengths, enabling new photochemical processes.

Purpose of the Study:

• To explore 3D rapid prototyping using NIR light-induced polymerization.
• To investigate the use of core/shell upconversion nanoparticles (UCNPs) for this technology.
• To analyze the polymerization process and resolution at microscale levels.

Main Methods:

• Synthesis of NaYF4:Yb3+,Tm3+/NaYF4 core/shell UCNPs with high NIR-to-UV conversion efficiency.
• Utilizing UCNPs to activate photoinitiators in photocurable resins under NIR excitation (975 nm).
• Fabrication of polymeric structures using NIR laser scanning photolithography.

Main Results:

• Efficient radical generation and in situ photopolymerization achieved with moderate NIR intensities (<10 W cm-2).
• Successful fabrication of both millimeter and sub-micron scale polymeric structures.
• Observed differences in polymer shell growth rates around nanoparticles influenced microscale resolution.

Conclusions:

• NIR-activated polymerization using UCNPs is a viable 3D printing strategy.
• The technology enables high-resolution microfabrication.
• Nanoparticle surface morphology impacts polymerization dynamics and printing resolution.