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
Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
Electrical, Computer, and Energy Engineering Department, University of Colorado, Boulder, CO, 80309, USA.
Adv Mater. 2020 Nov;32(47):e2003376. doi: 10.1002/adma.202003376. Epub 2020 Oct 1.
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.
体积增材制造（VAM）在单次光固化操作中即可形成完整的3D物体，不存在分层缺陷，能够制造出具有与其块状材料相当机械性能的3D打印聚合物部件。本研究首次报道了VAM打印的硫醇-烯树脂。硫醇-烯化学通过有序的分子网络可获得具有广泛机械性能的聚合物材料，使VAM突破了常用丙烯酸酯配方的限制。由于自由基硫醇-烯聚合不受氧气抑制，因此通过加入2,2,6,6-四甲基-1-哌啶氧基（TEMPO）作为自由基清除剂来引入VAM所需的非线性阈值响应。通过平衡抑制剂和引发剂的含量来实现反应动力学的调节。将此与吸收的体积光剂量的定量测量相结合，可以控制打印过程中的聚合物转化率和凝胶化。重要的是，这项工作由此建立了第一个用于时空控制体积能量分布的综合框架，展示了通过断层体积VAM在硫醇-烯树脂中3D打印的结构。对这种具有不同比例异氰脲酸酯和三甘醇单体的硫醇-烯体系进行机械表征，发现其机械响应具有高度可调性，比相同的丙烯酸酯基树脂更加通用。这拓宽了VAM可用材料和性能的范围，朝着高性能打印聚合物又迈进了一步。
