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Emerging 3D-printed ceramics, though showing unprecedented application potential, are typically vulnerable to fractures and unable to heal at room temperature. By contrast, their natural counterparts, human bones, exhibit extraordinary self-healing capability through the activation of stem cell osteoblasts that precipitate mineralized calluses to enable interfacial healing at body temperature. Inspired by bones, we here employ bacteria as artificial osteoblasts to enable healing of 3D-printed porous ceramics at room temperature. The healing behavior relies on bacteria-initiated precipitation of calcium carbonate crystals to bridge fracture interfaces of ceramics. We show that bacteria-loaded porous ceramics can heal fracture interfaces to restore 100% mechanical strength at room temperature, and the healed strength is not compromised by heating up to 500 C or by corrosion of alkalis and oxidants. The bacteria-assisted healing mechanism is revealed by systematic control experiments, and the healing strength is explained by cohesive fracture modeling. We further incorporate this method into 3D-printed ceramics and demonstrate on-demand healing of ceramic dental crowns, ceramic water membranes, and ceramic lattices, and autonomous healing of ceramic armor. As the first-generation healing mechanism of 3D-printed ceramics, this paradigm is expected to open promising avenues for revolutionizing the low-damage-tolerance nature of existing 3D-printed ceramics.
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Healable, memorizable, and transformable lattice structures made of stiff polymers
Abstract Emerging transformable lattice structures provide promising paradigms to reversibly switch lattice configurations, thereby enabling their properties to be tuned on demand. The existing transformation mechanisms are limited to nonfracture deformation, such as origami, instability, shape memory, and liquid crystallinity. In this study, we present a class of transformable lattice structures enabled by fracture and shape-memory-assisted healing. The lattice structures are additively manufactured with a molecularly designed photopolymer capable of both fracture healing and shape memory. We show that 3D-architected lattice structures with various volume fractions can heal fractures and fully restore stiffness and strength over two to ten healing cycles. In addition, coupled with the shape-memory effect, the lattice structures can recover fracture-associated distortion and then heal fracture interfaces, thereby enabling healing of lattice wing damages, mode-I fractures, dent-induced crashes, and foreign-object impacts. Moreover, by harnessing the coupling of fracture and shape-memory-assisted healing, we demonstrate reversible configuration transformations of lattice structures to enable switching among property states of different stiffnesses, vibration transmittances, and acoustic absorptions. These healable, memorizable, and transformable lattice structures may find broad applications in next-generation aircraft panels, automobile frames, body armor, impact mitigators, vibration dampers, and acoustic modulators.
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- Award ID(s):
- 1762567
- PAR ID:
- 10154077
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- NPG Asia Materials
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 1884-4049
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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