Photochemically Activated 3D Printing Inks: Current Status, Challenges, and Opportunities

Abstract

Abstract3D printing with light is enabled by the photochemistry underpinning it. Without fine control over our ability to photochemically gate covalent bond formation by the light at a certain wavelength and intensity, advanced photoresists with functions spanning from on‐demand degradability, adaptability, rapid printing speeds and tailored functionality are impossible to design. Herein, we critically assess recent advances in photoresist design for light‐driven 3D printing applications and provide an outlook of the outstanding challenges and opportunities. We achieve this by classing the discussed photoresists in chemistries that function photoinitiator‐free and those that require a photoinitiator to proceed. Such a taxonomy is based on the efficiency with which photons are able to generate covalent bonds, with each concept featuring distinct advantages and drawbacks.This article is protected by copyright. All rights reserved

Graphite Nitride Carbon (g-C3N4) and Borates as Near-UV Heterogeneous Photoinitiators for Acrylate Photopolymerization

“…Compared with traditional thermal polymerization, photopolymerization offers numerous advantages, including low energy consumption, minimal environmental impact, reduced side reactions, and a controllable reaction time. Such characteristics align with the principles of green chemistry, rendering photopolymerization a technology with robust development prospects that has garnered substantial attention across diverse sectors such as coatings, adhesives, and inks, − as well as in cutting-edge fields like high-resolution and high-precision fine structure molding and 3D printing. , …”

Photoreaction Drives Efficient, Precise, and Sustainable Additive Manufacturing

“…With respect to the light wavelength control, one should be aware that the highest reactivity may deviate from the absorption maximum, although a higher absorption may benefit the reactivity according to the First and Second Laws of Photochemistry. Thus, according to the research by the Barner-Kowollik group, the utilization of photochemical action plots may be needed for better understanding the relation between photochemical reactivity and absorptivity, 33 as displayed in Figure 15. One amazing added benefit for conducting such photochemical action plots is that one may achieve true λ-orthogonality that seems impossible from the UV−vis absorption spectra.…”

“…(d) Developed photoresist layer after λ-orthogonal printing under 330 and 435 nm, respectively. (Reproduced with permission from ref . Copyright 2024, Wiley-VCH.…”

“…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. 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 multi-material gradient structure would be in a crucial future path and need more efforts to control the photochemical reaction.…”

Recent Advances in Multi‐Photon 3D Laser Printing: Active Materials and Applications

“…In addition to the accessibility of printers, the development of suitable photocurable inks has evolved tremendously in recent years. [6][7][8][9] This can be seen in the wide variety of new inks that are suitable for different applications enabling for example, 3D printing with optical-quality surfaces, high-speed, high resolution, or biocompatibility, among others. However, due to the constant expansion of the field, there is an urgent need for the implementation of new features.…”