Institute of Applied Synthetic Chemistry, Technische Universität Wien, Getreidemarkt 9/163, 1060 Vienna, Austria.
Cubicure GmbH, Gutheil-Schoder-Gasse 17, Tech Park Vienna, 1230 Vienna, Austria.
Biomacromolecules. 2023 Apr 10;24(4):1751-1762. doi: 10.1021/acs.biomac.2c01505. Epub 2023 Mar 17.
3D printing of bio-based and renewable polymers such as lignin has gained research attention during the last few decades. We report on the synthesis and characterization of a liquid lignin-based photopolymer and its application in additive manufacturing (AM). Wheat straw soda lignin is liquified in an oxyalkylation reaction with propylene oxide under alkaline conditions and modified with methacryloyl chloride to obtain a lignin-based methacrylate resin. Ninety percent of the functional hydroxyl groups are grafted during the synthesis. The photopolymerization efficiency was evaluated by real-time-NIR-photorheology experiments with two different photoinitiators, leading to double bond conversions (DBC) of ≥80%. 3D-printing experiments of the methacrylated lignin were performed with the hot lithography technology. For the first time, a light-curable lignin derivative with a lignin content of over 30% was successfully 3D printed via vat photopolymerization without any reactive diluents, which is a significant improvement over current state-of-the-art solutions. This outstanding result is a motivating proof of concept and a promising starting point for the in-depth evaluation of bio-based precursors as an alternative to nonrenewable derivatives for 3D printing.
在过去几十年中，3D 打印生物基和可再生聚合物（如木质素）引起了研究关注。我们报告了一种基于液体木质素的光聚合材料的合成和表征及其在增材制造（AM）中的应用。麦草堿木素在碱性条件下与环氧丙烷进行氧烷基化反应液化，并与丙烯酰氯改性得到木质素基甲基丙烯酸酯树脂。在合成过程中，有 90%的功能羟基被接枝。通过使用两种不同的光引发剂进行实时 NIR 光流变学实验，评估了光聚合效率，导致双键转化率（DBC）≥80%。采用热光刻技术进行了甲基丙烯酰化木质素的 3D 打印实验。首次成功地通过 vat 光聚合打印了一种光固化木质素衍生物，其木质素含量超过 30%，而无需任何反应性稀释剂，这是对当前最先进解决方案的重大改进。这一出色的结果为基于生物的前体作为替代不可再生衍生物用于 3D 打印的概念验证提供了动力，并为深入评估提供了有希望的起点。
