Nanoparticle-enhanced vat photopolymerization in additive manufacturing

This article reviews the improvement of photopolymerization, primarily in terms of its rate, degree of conversion, and resolution, using nanoparticles. The studies identified in the current literature and available in indexed databases are thoroughly examined, with key findings discussed and summarized. The nanoparticles identified include metallic, semiconducting, upconversion, insulating, and other types. The primary mechanisms that enhance photopolymerization are localized surface plasmon resonance, photocatalytic effect, upconversion, and two-photon absorption. These studies are categorized accordingly. The methods used to assess the ability of nanoparticles to improve photopolymerization vary depending on the type of nanoparticle, the resin formulation, and the intended application. Consequently, we also examine the various assessment methods employed in these studies. Furthermore, we highlight the rapidly advancing field of additive manufacturing, particularly vat photopolymerization, which could greatly benefit from improvements in photopolymerization research. For this reason, the final section of this review discusses how findings in nanoparticle-enhanced photopolymerization can further advance vat photopolymerization in additive manufacturing. Recent advancements, such as the possibility of 3D printing with NIR light using thermal initiators and printing of highly opaque materials, should be further explored and improved.