3D printing complex architectures of responsive-hydratable polymers are enabled by stereolithography via photopolymerization. Yet, insufficient crosslinking leads to compromised structural integrity of the photopolymerized samples, which affects the functionality and reliability of hydrogel devices significantly. Here we investigate how curing parameters and ink formulation affect 3D printed PEGDA samples by using a combination of microfabrication, structural characterization, and reactive coarse-grained molecular dynamics simulation. Our findings show that the degree of curing exhibits a graded profile from confocal Raman spectroscopy and submicron pores from atomic force microscopy, both of which are also observed in our molecular simulations. Moreover, with environmental scanning electron microscopy, we probe the microscopic swelling and bending dynamics of 3D printed hydratable PEGDA structures as well as their structural integrity. Our in-depth characterization results reveal how hydrogel elasticity and irreversible densification due to pore formation highly depends on the exposure time, light intensity and the associated degree of crosslinking. This work provides new molecular insights into processing–structure relation in stereolithography 3D printing.

中文翻译：

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PEGDA 光聚合在微立体光刻术中对 3D 打印水凝胶结构和溶胀的影响

三维打印响应水合聚合物的复杂结构是由立体平版启用经由光聚合。然而，不充分的交联会导致光聚合样品的结构完整性受损，从而显着影响水凝胶装置的功能和可靠性。在这里，我们通过结合使用微细加工、结构表征和反应性粗粒分子动力学模拟来研究固化参数和油墨配方如何影响 3D 打印的 PEGDA 样品。我们的研究结果表明，固化程度显示出共焦拉曼光谱和原子力显微镜中的亚微米孔的分级分布，这两者也在我们的分子模拟中观察到。此外，通过环境扫描电子显微镜，我们探测了 3D 打印的可水合 PEGDA 结构的微观膨胀和弯曲动力学及其结构完整性。我们的深入表征结果揭示了水凝胶弹性和由于孔形成导致的不可逆致密化如何高度依赖于曝光时间、光强度和相关的交联度。这项工作为立体光刻 3D 打印中的加工-结构关系提供了新的分子见解。