Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing. Issue 47 (1st October 2020)

• Record Type: Journal Article
• Authors: Cook, Caitlyn C.; Fong, Erika J.; Schwartz, Johanna J.; Porcincula, Dominique H.; Kaczmarek, Allison C.; Oakdale, James S.; Moran, Bryan D.; Champley, Kyle M.; Rackson, Charles M.; Muralidharan, Archish; McLeod, Robert R.; Shusteff, Maxim
• Is Part Of: Advanced materials. Volume 32:Issue 47(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-01
• Subjects: acrylate -- photopolymerization -- thiol‐ene -- tomography -- volumetric additive manufacturing; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202003376
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 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. Abstract : Thiol‐ene resins are adapted for volumetric 3D printing by incorporating a threshold response using a polymerization inhibitor. This feature, combined with quantitative spatial control of the absorbed optical energy dose, makes volumetric additive manufacturing possible with a large new class of materials. Adjusting the monomer compositions of these thiol‐enes accesses a broad range of mechanical properties.