Colorful 3D Printing: A Critical Feasibility Analysis of Multi-Wavelength Additive Manufacturing

Abstract

Employing two colors of light to 3D print objects holds potential for accessing advanced printing modes, such as the generation of multi-material objects from a single print. Thus, dual-wavelength-driven photoreactive systems (reactions that require or utilize two wavelengths) and their exploitation as chemo-technological solutions for additive manufacturing technologies have experienced considerable development over the last few years. Such systems saw an increase in printing speeds, a decrease in resolution thresholds, andperhaps most importantlythe actual generation of multi-material objects. However, the pace at which such reactive systems are developed is moderate and varies significantly depending on the fashion in which the two colors of light are employed. Herein, we address for the first time the varying logic conjugations of light-activated chemical compounds in dual-wavelength photochemical processes in a systematic manner and consider their implications from a photochemical point of view. To date, four dual-wavelength reaction types have been reported, termed synergistic (λ1 AND λ2), antagonistic (reversed λ1 AND λ2), orthogonal (λ1 OR λ2), andmost recentlycooperative (λ1 AND λ2 or λ1 OR λ2). The progress of their implementation in additive manufacturing is assessed individually, and their concurrent and individual chemical challenges are identified. These challenges need to be addressed for future dual-wavelength photochemical systems to progress multi-wavelength additive manufacturing technologies beyond their current limitations.

Photoreaction Drives Efficient, Precise, and Sustainable Additive Manufacturing

“…As such, gradient structure design and synergistic printing of multi-materials will be an important research direction for innovative printing materials. However, how to realize the combination of multi-materials and precise structure design in an appropriate way will be a difficult problem that researchers have to face despite the attractive advances via reaction orthogonialty …”

“…However, how to realize the combination of multi-materials and precise structure design in an appropriate way will be a difficult problem that researchers have to face despite the attractive advances via reaction orthogonialty. 31 All in all, 3D printing technology is a technology full of potential and innovation. From its origins to its current development and its future outlook, we can see that its impact on human society is becoming more and more far-reaching.…”

“…Compared with traditional polymerization methods, the photopolymerization reaction has the advantages of a fast curing speed at low light intensity, short exposure time, less heat production, and the possibility of temporal and spatial control, which makes it the first choice for achieving high-quality 3D printing. In addition, various characteristics of the printed object in photopolymerization 3D printing can be easily adjusted by simply changing the formulation of the photopolymerizable resin, choosing the right initiator or selecting different wavelengths of light . It must be pointed out that the development of precise photocuring systems is currently necessary to achieve efficient 3D printing, and photochemical action plots may be needed as suggested by Barner-Kowollik et al . , Herein, this Perspective attempts to highlight the critical role of photoreaction design for high-quality 3D printing, in terms of producing high performance products with complex structures, creating mechanically robust and environmentally sustainable objects, and simultaneously increasing the printing speed and resolution.…”

“…In addition, various characteristics of the printed object in photopolymerization 3D printing can be easily adjusted by simply changing the formulation of the photopolymerizable resin, choosing the right initiator or selecting different wavelengths of light. 31 It must be pointed out that the development of precise photocuring systems is currently necessary to achieve efficient 3D printing, and photochemical action plots may be needed as suggested by Barner-Kowollik et al 32,33 Herein, this Perspective attempts to highlight the critical role of photoreaction design for highquality 3D printing, in terms of producing high performance products with complex structures, creating mechanically robust and environmentally sustainable objects, and simultaneously increasing the printing speed and resolution. Though detailed mechanism in photochemistry is not involved here, we agree that affording predesigned functions (e.g., photoluminescence) into the printed objects and collaborative printing of multimaterial gradient structure would be in a crucial future path and need more efforts to control the photochemical reaction.…”