The field of 3D printing is continuing its rapid development in both academic and industrial research environments. The development of 3D printing technologies has opened new implementations in rapid prototyping, tooling, dentistry, microfluidics, biomedical devices, tissue engineering, drug delivery, etc. Among different 3D printing techniques, photopolymerization-based process (such as stereolithography and digital light processing) offers flexibility over the final properties of the 3D printed materials (such as optical, chemical, and mechanical properties) using versatile polymer chemistry. The strategy behind the 3D photopolymerization is based on using monomers/oligomers in liquid state (in the presence of photoinitiators) that can be photopolymerized (via radical or cationic mechanism) upon exposure to light source of different wavelengths (depending on the photoinitiator system). An overview of recent evolutions in the field of photopolymerization-based 3D printing and highlights of novel 3D print...

Photopolymerization in 3D Printing

Sustainable near UV-curable acrylates based on natural phenolics for stereolithography 3D printing

Self-healing, reprocessing and 3D printing of transparent and hydrolysis-resistant silicone elastomers

Thiol–ene photopolymerization has been widely applied in polymer synthesis and the fabrication of optical devices via 3D printing due to its unique features such as low shrinkage stress and yielding homogeneous networks However, the poor storage stability and unpleasant odor of conventional primary thiols have limited their application Detailed evaluation of the photocuring properties of secondary thiols with low odor and good shelf-life stability is lacking In this study, we systematically discussed the thermal storage stability, photopolymerization kinetics, and mechanical, thermal, and physical properties of three types of multifunctional secondary thiols and one type of primary thiol The results show that all secondary thiol–ene systems exhibit better thermal storage stability (>7 days) at 60 °C than the primary thiol–ene system ( 154) show great potential for the fabrication of 3D optical devices with high resolution

Highly stable thiol–ene systems: from their structure–property relationship to DLP 3D printing

Volumetric additive manufacturing (VAM) forms complete 3D objects in a single photocuring operation without layering defects, enabling 3D printed polymer parts with mechanical properties similar to their bulk material counterparts. This study presents the first report of VAM-printed thiol-ene resins. With well-ordered molecular networks, thiol-ene chemistry accesses polymer materials with a wide range of mechanical properties, moving VAM beyond the limitations of commonly used acrylate formulations. Since free-radical thiol-ene polymerization is not inhibited by oxygen, the nonlinear threshold response required in VAM is introduced by incorporating 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a radical scavenger. Tuning of the reaction kinetics is accomplished by balancing inhibitor and initiator content. Coupling this with quantitative measurements of the absorbed volumetric optical dose allows control of polymer conversion and gelation during printing. Importantly, this work thereby establishes the first comprehensive framework for spatial-temporal control over volumetric energy distribution, demonstrating structures 3D printed in thiol-ene resin by means of tomographic volumetric VAM. Mechanical characterization of this thiol-ene system, with varied ratios of isocyanurate and triethylene glycol monomers, reveals highly tunable mechanical response far more versatile than identical acrylate-based resins. This broadens the range of materials and properties available for VAM, taking another step toward high-performance printed polymers.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.202003376

Hyun Sang Park

Papers

Tough, stable spiroacetal thiol‐ene resin for 3D printing