Reprintable self-healing polymer networks
November 10-14, 2019
We report a versatile approach to designing printable, re-processable polymer networks with controllable mechanical properties. The approach involves epoxy-based oligomeric building blocks which are reversibly crosslinked within reversible networks. The reversible crosslinking was enabled by Diels-Alder (DA) reactions between furan moieties of the oligomeric precursor and maleimide moieties of a crosslinker agent. The polymer networks formed in ambient conditions by DA reaction reversibly dissociated at elevated temperatures via retro DA reaction. The low viscosity of dissociated networks between 80 and 145 oC facilitated re-processing of the materials via injection molding or 3D printing. Importantly, the presence of reversible chemical crosslinks between furan and maleimide moieties enabled fast curing of the polymer resin and improved interlayer adhesion at the interfaces between the deposited layers during fused deposition modelling. Using this approach, the same oligomeric precursor could be used with variable amount of a crosslinker for fabrication of a series of polymer networks with the glass transition temperatures precisely controlled between -10 and 30 oC. The polymer networks demonstrated programmable MPa-range elastic moduli, and fast self-healing behavior. Moreover, the materials were rendered stimuli responsive via covalent attachment of light-responsive dyes, whose photoisomerization was triggered by exposure to UV irradiation. These results suggest a new and promising pathway into development of versatile materials for additive manufacturing of multifunctional adaptable structures.
Svetlana Sukhishvili, Qing Zhou, and Frank Gardea, "Reprintable self-healing polymer networks" in "Composites at Lake Louise 2019", John Kieffer, University of Michigan, USA Erik Spoeke, Sandia National Laboratories, USA Meisha Shofner, Georgia Institution of Technology, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/composites_all_2019/6