Shaukat Usman, Sölle Bernhard, Rossegger Elisabeth, Rana Sravendra, Schlögl Sandra
Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
School of Engineering, Energy Acres, University of Petroleum & Energy Studies (UPES), Dehradun 248007, India.
Polymers (Basel). 2022 Dec 8;14(24):5377. doi: 10.3390/polym14245377.
As an energy-efficient additive manufacturing process, vat photopolymerization 3D-printing has become a convenient technology to fabricate functional devices with high resolution and freedom in design. However, due to their permanently crosslinked network structure, photopolymers are not easily reprocessed or repaired. To improve the environmental footprint of 3D-printed objects, herein, we combine the dynamic nature of hydroxyl ester links, undergoing a catalyzed transesterification at elevated temperature, with an acrylate monomer derived from renewable resources. As a sustainable building block, we synthesized an acrylated linseed oil and mixed it with selected thiol crosslinkers. By careful selection of the transesterification catalyst, we obtained dynamic thiol-acrylate resins with a high cure rate and decent storage stability, which enabled the digital light processing (DLP) 3D-printing of objects with a structure size of 550 µm. Owing to their dynamic covalent bonds, the thiol-acrylate networks were able to relax 63% of their initial stress within 22 min at 180 °C and showed enhanced toughness after thermal annealing. We exploited the thermo-activated reflow of the dynamic networks to heal and re-shape the 3D-printed objects. The dynamic thiol-acrylate photopolymers also demonstrated promising healing, shape memory, and re-shaping properties, thus offering great potential for various industrial fields such as soft robotics and electronics.
作为一种节能的增材制造工艺，光固化3D打印已成为一种便捷的技术，可用于制造具有高分辨率和设计自由度的功能器件。然而，由于其永久交联的网络结构，光聚合物不易再加工或修复。为了改善3D打印物体的环境影响，在此，我们将羟基酯键在高温下发生催化酯交换反应的动态特性与一种源自可再生资源的丙烯酸酯单体相结合。作为一种可持续的构建模块，我们合成了一种丙烯酸化亚麻籽油，并将其与选定的硫醇交联剂混合。通过仔细选择酯交换催化剂，我们获得了具有高固化速率和良好储存稳定性的动态硫醇-丙烯酸酯树脂，这使得能够对结构尺寸为550微米的物体进行数字光处理（DLP）3D打印。由于其动态共价键，硫醇-丙烯酸酯网络能够在180℃下22分钟内释放其初始应力的63%，并且在热退火后显示出增强的韧性。我们利用动态网络的热激活回流来修复和重塑3D打印物体。动态硫醇-丙烯酸酯光聚合物还表现出有前景的修复、形状记忆和重塑性能，因此在软机器人和电子等各种工业领域具有巨大潜力。
