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Additive manufacturing, more commonly known as 3D-printing, is bringing about a grand technological transformation in material design and fabrication. In contrast to traditional fabrication techniques, 3D-printing features rapid prototyping, complex and customized 3D structural designs, and multi-material integration. Among current 3D-printing systems, direct-ink-writing (DIW) exhibits unique functionalities due to its mild operation conditions and the ability to integrate various organic and inorganic entities. Although supramolecular binding motifs are increasingly utilized in 3D-printing designs, the optimization of 3D-printable inks remains largely empirical. In this thesis, we present two strategies to rationally design supramolecularly crosslinked 3D-printable hydrogels, including (1) micro-crystallization and (2) hierarchical co-assembly-enabled DIW 3D-printing. We also highlight the follow-up applications using either of the strategies and the design principles when aiming for a specific purpose.
First, we designed a 3D-printable hydrogel using the micro-crystallization of polypseudorotaxanes via kinetic trapping. The installation of stoppers and/or speed bumps on polymer chain ends enabled the formation of kinetically trapped polypseudorotaxane networks suitable for DIW 3D-printing. We systematically studied the assembly between polyethylene glycol (PEG) and α-CD and established a clear structure-property relationship. Harnessing the kinetic trapping characteristic, we designed 3D-printed heterostructures composed of two polyrotaxane networks, which were able to shape morph upon moisture variations.
Second, we applied the kinetic trapping principles to design 3D-printable pro-slide-ring crosslinker hydrogels composed of PEG and γ-CD. The supramolecularly crosslinked hydrogels were thereafter converted to crystalline-domain-reinforced slide-ring materials. Here, the micro-crystallization not only enabled 3D-printing but also reinforced the hydrogel material in terms of rigidity. The slide-ring cross-linkages and the crystalline domains overcame the trade-offs between toughness and elasticity, with the structure-property relationship elucidated through high-throughput synthesis and machine learning. The hydrogels were fabricated into high-performance capacitive stress sensors to demonstrate their excellent mechanical properties and material versatility.
Third, we introduced our efforts of using the hierarchical co-assembly strategy to develop 3D-printable 1,3,5-tricarboxamide (BTA) materials. We designed and synthesized 12 BTA monomers and employed them for two applications, including liquid crystalline materials for optical property modulations and the construction of tough hydrogel materials. Molecularly, we studied the self-assembly and co-assembly of BTA motifs, particularly in a crosslinked network. Macroscopically, we synthesized BTA-based crosslinked networks for optical and mechanical property investigations to correlate the structural information molecularly. We also demonstrated the construction of 3D-printed BTA materials, exhibiting superior features compared to materials synthesized in bulk.
M. Tang, Z. Zhong, C. Ke, “Advanced supramolecular design for direct ink writing of soft materials” Chemical Society Reviews, 2023, 52, 1614–1649
Q. Lin,# L. Li,# M. Tang,# S. Uenuma,# (equal contribution) J. Samanta, S. Li, X. Jiang, L. Zou, K. Ito, and C. Ke, "Kinetic trapping of 3D-printable cyclodextrin-based poly(pseudo)rotaxane networks" Chem, 2021, 7, 9, 2442–2459.
Tang, Miao, "Supramolecular design of 3D-printable hydrogels for functional materials" (2023). Dartmouth College Ph.D Dissertations. 205.
Available for download on Thursday, May 01, 2025