Extrusion printing of ionic–covalent entanglement hydrogels with high toughness

Bakarich, Shannon; Panhuis, Marc in het; Beirne, Stephen; Wallace, Gordon G.; Spinks, Geoffrey M.

doi:10.1039/c3tb21159b

Cited by 156 publications

(155 citation statements)

References 22 publications

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“…If the field is to progress, advanced manufacturing techniques that integrate dielectric elastomers and hydrogels need to be developed. [7] Fabrication techniques specific to hydrogels have already been developed, including extrusion three-dimensional (3D) printing, [24,[32][33][34][35] digital projection based techniques, [36] and screen printing [37,38] . Extrusion printing techniques in particular are most easily capable of multi-material printing at high resolution and low costs.…”

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confidence: 99%

“…Extrusion printing techniques in particular are most easily capable of multi-material printing at high resolution and low costs. [33,34] Recently, Robinson et al fabricated a soft sensor with an ionicliquid based gel and a silicone elastomer by combining soft lithography with extrusion printing. [24] Although recent studies have successfully fabricated stretchable electronics consisting entirely of soft materials, conductive hydrogels and dielectric elastomers, thus far these fabrication techniques have relied on casting or a combination of extrusion printing with other methods.…”

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confidence: 99%

“…[33] The entire system was housed inside a nitrogen environment. The relative humidity (RH) of the environment was fixed at 43%…”

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confidence: 99%

“…A significant proportion of rheological modifiers used in extrusion printing are sensitive to the ionic strength of the precursor, [33,34,48,49] and may lead to precipitation [50][51][52] or flocculation [53] of the rheological modifiers at the high salt concentrations necessary for good electrical conductivity and water retention. This requirement excludes many of the modifiers that are routinely used for hydrogel printing.…”

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confidence: 99%

“…By performing a power-law fit of the data in Figure 2b, we obtain a value of 0.148 for the shear-thinning exponent n in the high-strain rate region ( > 1 [24,33,35,49] .…”

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3D Printing of Transparent and Conductive Heterogeneous Hydrogel–Elastomer Systems

et al. 2017

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A hydrogel–dielectric‐elastomer system, polyacrylamide and poly(dimethylsiloxane) (PDMS), is adapted for extrusion printing for integrated device fabrication. A lithium‐chloride‐containing hydrogel printing ink is developed and printed onto treated PDMS with no visible signs of delamination and geometrically scaling resistance under moderate uniaxial tension and fatigue. A variety of designs are demonstrated, including a resistive strain gauge and an ionic cable.

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confidence: 99%

“…[33] The entire system was housed inside a nitrogen environment. The relative humidity (RH) of the environment was fixed at 43%…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…By performing a power-law fit of the data in Figure 2b, we obtain a value of 0.148 for the shear-thinning exponent n in the high-strain rate region ( > 1 [24,33,35,49] .…”

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confidence: 99%

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3D Printing of Transparent and Conductive Heterogeneous Hydrogel–Elastomer Systems

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Printability and Techniques

2022

3D Printing of Foods

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A Novel Design Strategy for Fully Physically Linked Double Network Hydrogels with Tough, Fatigue Resistant, and Self‐Healing Properties

Chen

Zhu

Chen

et al. 2015

Adv Funct Materials

529

370

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1 wileyonlinelibrary.com recoverability and self-healing property, due to their intrinsic structural heterogeneity and/or lack of effi cient energydissipation mechanisms, [ 13 ] which greatly limit their uses for other applications requiring highly mechanical properties such as cartilage, tendon, muscle, and blood vessel.Many efforts have been made to develop tough hydrogels with new microstructures and toughening mechanisms, such as double network hydrogels, [ 14 ] nanocomposite hydrogels, [ 15 ] sliding-ring hydrogels, [ 16 ] macromolecular microsphere composite hydrogels, [ 17 ] tetrapolyethylene glycol hydrogels, [ 18 ] hydrophobically associated hydrogels, [ 19,20 ] and dipole-dipole or hydrogen bonding enhanced hydrogels. [ 21,22 ] Among them, double network (DN) hydrogels have demonstrated their excellent mechanical properties. The existing knowledge of DN gels from synthesis methods, network structures, to toughening mechanisms mainly comes from chemically cross-linked DN gels. [ 23 ] Both networks with contrasting structures in DN gels are separately crosslinked by covalent bonds, [ 24 ] and the interpenetration of two contrasting networks makes the chemically linked DN gels both tough and soft, as evidenced by stiffness (elastic modulus of 0.1-1.0 MPa), strength (failure tensile stress of 1-10 MPa, strain 1000%-2000%, failure compressive stress 20-60 MPa, strain 90%-95%), and toughness (tearing fracture energy of 10 2 -10 3 J m −2 ). [ 23 ] Chemically linked DN gels have comparable toughness to cartilage and rubber. The toughening mechanisms are largely based on "sacrifi cial bonds" that break from the fi rst network to effectively dissipate energy, protect the second network, sustain stress, and store elastic energy, thus to reinforce the gels. However, the fracture of the fi rst network also causes irreversible and permanent bond breaks, making the gels very diffi cult to be repaired and recovered from damages and fatigues. [ 25 ] Thus, the internal fracture process of the fi rst network is considered to be critical for toughness enhancement, because relatively large damage zones formed in the fi rst network allow for more accumulated damage before macroscopic crack propagation occurs throughout whole networks. [ 26,27 ] Double network (DN) hydrogels with two strong asymmetric networks being chemically linked have demonstrated their excellent mechanical properties as the toughest hydrogels, but chemically linked DN gels often exhibit negligible fatigue resistance and poor self-healing property due to the irreversible chain breaks in covalent-linked networks. Here, a new design strategy is proposed and demonstrated to improve both fatigue resistance and self-healing property of DN gels by introducing a ductile, nonsoft gel with strong hydrophobic interactions as the second network. Based on this design strategy, a new type of fully physically cross-linked Agar/hydrophobically associated polyacrylamide (HPAAm) DN gels are synthesized by a simple one-pot method. Agar/ HPAAm DN gels exhibit excellent mech...

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Extrusion printing of ionic–covalent entanglement hydrogels with high toughness

Cited by 156 publications

References 22 publications

3D Printing of Transparent and Conductive Heterogeneous Hydrogel–Elastomer Systems

3D Printing of Transparent and Conductive Heterogeneous Hydrogel–Elastomer Systems

Printability and Techniques

A Novel Design Strategy for Fully Physically Linked Double Network Hydrogels with Tough, Fatigue Resistant, and Self‐Healing Properties

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