Reversible bidirectional bending of hydrogel-based bilayer actuators

Li, Xue; Cai, Xiangbin; Gao, Yongfeng; Serpe, Michael J.

doi:10.1039/c7tb00426e

Cited by 119 publications

(96 citation statements)

References 31 publications

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“…At both temperatures, the mat shrank significantly in the direction of fibers' alignment and swell in the perpendicular direction. Since pH 3 is lower than the p K a of the copolymer (6.2; Figure S5, Supporting Information), the carboxylic acid groups of AA moieties in the polymer backbone remain protonated and hence in the hydrophobic state . Therefore, the change in dimensions is mainly controlled by the conformational changes of NIPAm moieties of the copolymer.…”

Section: Resultsmentioning

confidence: 99%

“…Soft actuators with bilayer structure have been previously reported . Their actuation relies on the stimuli‐induced anisotropic size change of two attached layers.…”

Section: Introductionmentioning

confidence: 99%

“…Their actuation relies on the stimuli‐induced anisotropic size change of two attached layers. Li et al have prepared bilayer actuators based on a semi‐interpenetrating network of poly( N ‐isopropylacrylamide) (PNIPAm) and poly(diallyldimethylammonium) on a passive layer of polydimethylsiloxane, which can undergo reversible bidirectional bending to grip an object in response to temperature and pH stimuli. Cheng et al have fabricated a four‐arm gripper based on two layers of PNIPAm and poly(2‐(dimethylamino) ethyl methacrylate), which rapidly responses to both temperature and pH.…”

Section: Introductionmentioning

confidence: 99%

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Composite Polymeric Membranes with Directionally Embedded Fibers for Controlled Dual Actuation

Liu

Bakhshi

Jiang

et al. 2018

Macromol. Rapid Commun.

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In this paper, preparation method and actuation properties of an innovative composite membrane composed of thermo- and pH-responsive poly(N-isopropylacrylamide-co-acrylic acid) fibers (average diameter ≈ 905 nm) embedded within a passive thermoplastic polyurethane (TPU) matrix at different angles with degree of alignment as high as 98% are presented. The composite membrane has a gradient of TPU along the thickness. It has the capability of temperature- and pH-dependent direction-, and size-controlled actuation in few minutes. The stresses generated at the responsive fiber and nonresponsive matrix provide actuation, whereas the angle at which fibers are embedded in the matrix controls the actuation direction and size. The temperature has no effect on actuation and actuated forms at pH 7 and above, whereas the size of the actuated forms can be controlled by the temperature at lower pH. The membranes are strong enough to reversibly lift and release ≈426 times weight of their own mass (2.47 g metal ring is lifted by a 5.8 mg membrane). Soft actuators are of interest as smart scaffolds, robotics, catalysis, drug release, energy storage, electrodes, and metamaterials.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Soft actuators with bilayer structure have been previously reported . Their actuation relies on the stimuli‐induced anisotropic size change of two attached layers.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Composite Polymeric Membranes with Directionally Embedded Fibers for Controlled Dual Actuation

Liu

Bakhshi

Jiang

et al. 2018

Macromol. Rapid Commun.

View full text Add to dashboard Cite

show abstract

“…Later, several studies that either used cross‐linked PNIPAM as the active layer (changes volume with temperature) and hydrophobic polymers as the passive layer in a bilayer system or made complex patterns by photolithography were put forward, providing differentially cross‐linked hydrogels, patterned bilayers, interpenetrating networks with PNIPAM as the active layer, combinations of two hydrogel layers of differential swellability, etc. for shape transitions …”

Section: Design Strategies For Inducing Actuation By Temperature Watmentioning

confidence: 99%

“…Similarly, the network collapses when the acid groups are protonated at low pH. When such hydrogel polymers or their interpenetrating networks are used as active layers in a bilayer system, actuation is controlled by pH …”

Section: Ph‐ and Multifunctional Hydrogel Actuatorsmentioning

confidence: 99%

Progress in the Field of Water‐ and/or Temperature‐Triggered Polymer Actuators

Agarwal

Jiang

Chen

2018

Macro Materials & Eng

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Water‐ and/or temperature‐triggered polymer actuators have great potential in robotics, microfabrication and micromanipulation, cell culture, artificial scaffolds, muscles, and motors. In the past few years, a large amount of work has been carried out, and several innovative concepts have been proposed to address challenges such as actuation with large‐scale displacement in a very short time, actuation of large‐sized samples, complex 3D shaping, directional control, multiresponsive actuation, and strong actuators. Herein, the progress made in the field of actuators triggered by water, temperature, and a combination of both is presented, emphasizing the new concepts of fast and direction‐controlled actuation, the corresponding mechanisms, the associated challenges, and future tasks and perspectives.

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Harnessing the Power of Stimuli‐Responsive Polymers for Actuation

Wan

Zhang

et al. 2019

Adv Funct Materials

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A common behavior found in nature is the ability of plants and animals to naturally respond to their surroundings through actuation. Stimuli‐responsive polymers exhibit the same ability to naturally respond to changes in their environment, although manipulating them in a manner that allows their responses to be harnessed to do work via actuation is far from trivial. In this Review, examples that use temperature, pH, light, and electric field (and other) stimulation for actuation are highlighted. The actuation can result in materials that can be used to grip, lift, and move objects as well as for their own movement. As tremendous progress is being made in this research area, it is hard to imagine a future without these materials impacting lives in some way.

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Reversible bidirectional bending of hydrogel-based bilayer actuators

Abstract: Semi-IPN hydrogel-based bilayers were fabricated and exhibited unique bidirectional bending behavior in response to solution temperature and pH, which is vastly different from what is observed for bilayers composed of only conventional hydrogels.

Cited by 119 publications

References 31 publications

Composite Polymeric Membranes with Directionally Embedded Fibers for Controlled Dual Actuation

Composite Polymeric Membranes with Directionally Embedded Fibers for Controlled Dual Actuation

Progress in the Field of Water‐ and/or Temperature‐Triggered Polymer Actuators

Harnessing the Power of Stimuli‐Responsive Polymers for Actuation

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