A mechanically robust hydrogel with thermally induced plasticity and a shape memory effect

Kang, Peng; Yu, Hansen; Hao, Xiang; Yasin, Akram; Zhang, Xingyuan

doi:10.1039/c7sm00045f

Cited by 31 publications

(29 citation statements)

References 35 publications

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“…(B) Elongation ratio k versus recovery time t rec . Circles: experimental data in recovery tests followed cyclic deformation with k max = 2.5. Solid line: results of simulation.…”

Section: Fitting Of Observationssupporting

confidence: 82%

“…The ability of the model to describe observations is confirmed by fitting experimental data on (a) poly(vinyl alcohol) (PVA) gel, where chains are covalently crosslinked with glutaraldehyde and physically linked with borate ions, (b) poly(methacrylic acid– N ‐vinyl pyrrolidone–ethylene glycol methyl ether methacrylate) (MAAc‐VP‐PEGMA) gel with chains connected by hydrogen bonds between MAAc and VP segments, (c) poly(acrylamide–acrylic acid) (AAm‐AAc) gel, whose chains are bridged by metal‐coordination bonds with Fe 3+ ions, (d) poly(acrylamide–acrylic acid– n ‐octadecyl acrylate) (AAm‐AAc‐ODA) gel physically crosslinked with hydrophobic ODA aggregates and ionic complexes between Fe 3+ cations and carboxylic groups, and (e) AAm‐AAc gel, where chains are covalently crosslinked with BIS and physically bonded by Fe 3+ ions.…”

Section: Introductionmentioning

confidence: 88%

“…We proceed with matching observations on AAm‐AAc‐ODA gel. First, micellar copolymerization was conducted of AAm monomers (12 wt %), AAc monomers (10 wt % of AAm), and ODA monomers (35 wt % of AAm) in an aqueous solution of sodium dodecyl sulfate (SDS, 18 wt %) and sodium chloride (1.5 M) by using ammonium persulfate (1 wt %) as an initiator.…”

Section: Fitting Of Observationsmentioning

confidence: 99%

“…(A) Tensile stress σ versus elongation ratio k . Circles: experimental data on AAm‐AAc‐ODA gel in cyclic test with strain rate

\overset{ɛ}{true} = 0.083

s −1 and maximum elongation ratio k max = 2.5. Other symbols: experimental data along the reloading paths after recovery for various times t rec min.…”

Section: Fitting Of Observationsmentioning

confidence: 99%

“…DN gels able to recover within a few minutes demonstrate an exponential decay in residual strain with recovery time t rec . When the recovery process requires more time, it involves two stages: elongation ratio k decreases rapidly with t rec at the first stage, and reduces slowly at the final stage. Comparison of observations on as‐prepared and fully swollen gel specimens shows that the duration of total recovery is weakly affected by degree of swelling The growth of maximum elongation ratio under stretching k max induces an appropriate increase in recovery time .…”

Section: Introductionmentioning

confidence: 98%

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Self‐recovery and fatigue of double‐network gels with permanent and reversible bonds

Drozdov

Christiansen

Düşünceli

et al. 2019

J Polym Sci B Polym Phys

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Double‐network (DN) gels subjected to cyclic deformation (stretching up to a fixed strain followed by retraction down to the zero stress) demonstrate a monotonic decrease in strain with time (self‐recovery). Observations show that the duration of total recovery varies in a wide interval (from a few minutes to several days depending on composition of the gel), and this time is strongly affected by deformation history. A model is developed for the kinetics of self‐recovery. Its ability to describe stress–strain diagrams in cyclic tests with various periods of recovery is confirmed by comparison with observations on several DN gels. Numerical simulation reveals pronounced enhancement of fatigue resistance in multi‐cycle tests with stress‐ and strain‐controlled programs when subsequent cycles of deformation are interrupted by intervals of recovery. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 438–453

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“…(B) Elongation ratio k versus recovery time t rec . Circles: experimental data in recovery tests followed cyclic deformation with k max = 2.5. Solid line: results of simulation.…”

Section: Fitting Of Observationssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 88%

Section: Fitting Of Observationsmentioning

confidence: 99%

“…(A) Tensile stress σ versus elongation ratio k . Circles: experimental data on AAm‐AAc‐ODA gel in cyclic test with strain rate

\overset{ɛ}{true} = 0.083

s −1 and maximum elongation ratio k max = 2.5. Other symbols: experimental data along the reloading paths after recovery for various times t rec min.…”

Section: Fitting Of Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 3 more Smart Citations

Self‐recovery and fatigue of double‐network gels with permanent and reversible bonds

Drozdov

Christiansen

Düşünceli

et al. 2019

J Polym Sci B Polym Phys

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Dual‐Encryption in a Shape‐Memory Hydrogel with Tunable Fluorescence and Reconfigurable Architecture

et al. 2021

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Materials capable of shape‐morphing and/or fluorescence imaging have practical significances in the fields of anti‐counterfeiting, information display, and information protection. However, it's challenging to realize these functions in hydrogels due to the poor mechanical properties and lack of tunable fluorescence. A tough hydrogel with good shape‐memory ability and phototunable fluorescence is reported here, which affords reprogrammable shape designing and information encoding for dual‐encryption. This hydrogel is prepared by incorporating donor–acceptor chromophore units into a poly(1‐vinylimidazole‐co‐methacrylic acid) network, in which the dense intra‐ and interchain hydrogen bonds lead to desirable features including high stiffness, high toughness, and temperature‐mediated shape‐memory property. Additionally, the hydrogel shows photomediated tunable fluorescence through a unimer‐to‐dimer transformation of the chromophores. By combining photolithography and origami/kirigami designs, hydrogel sheets encoded with fluorescent patterns can deform into specific 3D configurations. The geometrically encrypted fluorescent information in the architected hydrogels is readable only after sequential shape recovery and UV light irradiation. As demonstrated by proof‐of‐concept experiments, both the fluorescent pattern and the 3D configuration are reprogrammable, facilitating repeated information protection and display. The design of tough hydrogels with rewritable fluorescent patterns and reconfigurable shapes should guide the future development of smart materials with improved security and wider applications in aqueous environments.

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Stiffness Variable Polymers Comprising Phase‐Changing Side‐Chains: Material Syntheses and Application Explorations

et al. 2022

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lack the adaptability biological muscles have for variable working environments. Emerging opportunities in airborne and submarine vehicles, agricultural manipulations, biomedical devices, and wearable electronics require materials with variable rigidity to respond to dynamically changing conditions. [3][4][5][6] The mechanical impedance of such materials can be altered or fine-tuned to allow the system to adapt without a sophisticated control algorithm. For example, when grasping a fragile object such as an egg using a gripper, a stiffness variable material provides an adaptive contact force to optimally complete the task. Similarly, bio-inspired robots and wearable exoskeletons require stiffness variable materials capable of a large stiffness change to provide structural load-bearing and mechanical work output. In the softened state, the material can deform to locomote, maneuver, and absorb the energy arising from a collision or when interfacing with the human body. Some applications, such as medical endoscope designs, involve "move-and-hold" operations. This is where a variable-stiffness structure that holds a particular orientation in space or rigidly supports a load is able to become deformable on demand to change shape or reposition. [7] Other potential applications that can benefit from variable stiffness materials include biomechanically compatible sensor insertions for neural implants, vibration, and noise control in aerospace structures, and conformal shape morphing robotic systems. Requirements of Stiffness Variable MaterialsTo impart the perceived smart and adaptive systems with versatile and advantageous functionalities matching or surpassing those of natural systems, the stiffness variable materials should possess the following important features:1. Wide modulus variation: A range of modulus variation greater than 100 or even 1000-fold is required. A high modulus is desired for load-bearing and supporting freestanding structures, while a low modulus provides conformation, shape transformation, energy absorption, and dissipation. 2. Mild stimulus: A mild stimulus to trigger the stiffness variable operation, such as a narrow temperature span in Stiffness variable materials have been applied in a variety of engineering fields that require adaptation, automatic modulation, and morphing because of their unique property to switch between a rigid, load-bearing state and a soft, compliant state. Stiffness variable polymers comprising phase-changing side-chains (s-SVPs) have densely grafted, highly crystallizable long alkyl sidechains in a crosslinked network. Such a bottlebrush network-like structure gives rise to rigidity modulation as a result of the reversible crystallization and melting of the side chains. The corresponding modulus changes can be more than 1000-fold within a narrow temperature span, from ≈10 2 MPa to ≈10 2 kPa or lower. Other important properties of the s-SVP, such as stretchability, optical transmittance, and adhesion, can also be altered. This work reviews the underlying molecular mech...

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A mechanically robust hydrogel with thermally induced plasticity and a shape memory effect

Cited by 31 publications

References 35 publications

Self‐recovery and fatigue of double‐network gels with permanent and reversible bonds

Self‐recovery and fatigue of double‐network gels with permanent and reversible bonds

Dual‐Encryption in a Shape‐Memory Hydrogel with Tunable Fluorescence and Reconfigurable Architecture

Stiffness Variable Polymers Comprising Phase‐Changing Side‐Chains: Material Syntheses and Application Explorations

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