Photopolymerization is a ubiquitous, indispensable technique widely applied in applications from coatings, inks, and adhesives to thermosetting restorative materials for medical implants, and the fabrication of complex macroscale, microscale, and nanoscale 3D architectures via additive manufacturing. However, due to the brittleness inherent in the dominant acrylate‐based photopolymerized networks, a significant need exists for higher performance resin/oligomer formulations to create tough, defect‐free, mechanically ductile, thermally and chemically resistant, high modulus network polymers with rapid photocuring kinetics. This study presents densely cross‐linked triazole‐based glassy photopolymers capable of achieving preeminent toughness of ≈70 MJ m−3and 200% strain at ambient temperature, comparable to conventional tough thermoplastics. Formed either via photoinitiated copper(I)‐catalyzed cycloaddition of monomers containing azide and alkyne groups (CuAAC) or via photoinitiated thiol‐ene reactions from monomers containing triazole rings, these triazole‐containing thermosets completely recover their original dimensions and mechanical behavior after repeated deformations of 50% strain in the glassy state over multiple thermal recovery–strain cycles.
Nature excels in both self-healing and 3D shaping; for example, self-healable human organs feature functional geometries and microstructures. However, tailoring man-made self-healing materials into complex structures faces substantial challenges. Here, we report a paradigm of photopolymerization-based additive manufacturing of self-healable elastomer structures with free-form architectures. The paradigm relies on a molecularly designed photoelastomer ink with both thiol and disulfide groups, where the former facilitates a thiol-ene photopolymerization during the additive manufacturing process and the latter enables a disulfide metathesis reaction during the self-healing process. We find that the competition between the thiol and disulfide groups governs the photocuring rate and self-healing efficiency of the photoelastomer. The self-healing behavior of the photoelastomer is understood with a theoretical model that agrees well with the experimental results. With projection microstereolithography systems, we demonstrate rapid additive manufacturing of single- and multimaterial self-healable structures for 3D soft actuators, multiphase composites, and architected electronics. Compatible with various photopolymerization-based additive manufacturing systems, the photoelastomer is expected to open promising avenues for fabricating structures where free-form architectures and efficient self-healing are both desirable.
more » « less- NSF-PAR ID:
- 10153903
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- NPG Asia Materials
- Volume:
- 11
- Issue:
- 1
- ISSN:
- 1884-4049
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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