Hierarchical Multi‐Step Folding of Polymer Bilayers

Stoychev, Georgi; Turcaud, Sébastien; Dunlop, John W. C.; Ionov, Leonid

doi:10.1002/adfm.201203245

Cited by 148 publications

(149 citation statements)

References 22 publications

(18 reference statements)

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“…The control of directionality by orienting directing structural elements within the fl exible matrix and by combining bending and curling elicits more complex kinematic patterns that cannot be attained when using simple bilayer structures. [42][43][44] Alignment of the GFs at an angle of 45° with respect to L (AG/OGF@AG, Figure 1 g) restricted the hydration-induced expansion along the direction of the GFs in the OGF@AG layer and resulted in either left-handed or right-handed coiling of the strip into a helix upon exposure to a weak fl ow of humid air ( Figure 3 d and Movie S4, Supporting Information). When the AG/OGF@AG strip (5 mm wide, 100 µm thick) was placed on a moist substrate with the OGF@AG layer in contact with the surface, it coiled into a helix that had the OGF@AG layer on the outer and the AG layer on the inner surface (Movie S5, Supporting Information).…”

Section: Directing the Motion By Orientated Reinforcing Elementsmentioning

confidence: 99%

Directed Motility of Hygroresponsive Biomimetic Actuators

Zhang

Чижик

Wen

et al. 2015

Adv Funct Materials

110

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The capability of cellulose microfibrils to elicit directionality by anisotropically restricting the deformation of amorphous biogenic matrices is central to the motility of many plants as motoric and shape‐restoring elements. Herein, an approach is described to control directionality of artificial composite actuators that mimic the hygroinduced motion of composite plant tissues such as the opening of seed pods, winding of plant tendrils, and burial of seed awns. The actuators are designed as bilayer structures where single or double networks of buried parallel glass fibers reinforce the composite. By anisotropically restricting the expansion along certain directions they also effectively direct the mechanical reconfiguration, thereby determining the mechanical effect. A mathematical model is developed to quantify the kinematic response of fiber‐reinforced actuators. Within a broader context, the results of this study provide means for control over mechanical deformation of artificial dynamic elements that mimic the oriented fibrous architectures in biogenic motoric elements.

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Section: Directing the Motion By Orientated Reinforcing Elementsmentioning

confidence: 99%

Directed Motility of Hygroresponsive Biomimetic Actuators

Zhang

Чижик

Wen

et al. 2015

Adv Funct Materials

110

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“…By mimicking the sophisticated hierarchical structures present in nature, the motion of polymer films has been successfully demonstrated in several cases. [23][24][25][26][27][28][29][30] For example, hydrogel bilayers embedded with intersecting inorganic platelets or cellulose fibrils have exhibited pine-cone-like bending and pod-like twisting motions. 24,31 However, the practical applications of these actuators were limited because of the low modulus and weak mechanical strength of the hydrogels.…”

Section: Introductionmentioning

confidence: 99%

A monolithic hydro/organo macro copolymer actuator synthesized via interfacial copolymerization

et al. 2017

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Synthetic polymer actuators have attracted increasing attention for their potential applications in artificial muscles, soft robotics and sensors. The majority of previous efforts have focused on smart hydrogels with bilayer structures that can change their shape in response to environmental stimuli, such as temperature, light and certain chemicals. However, the practical application of hydrogels is limited because of their low modulus and weak mechanical strength. Here we synthesized a robust monolithic actuator of a macro-scale hydro/organo binary cooperative Janus copolymer film. The process involves direct, one-step interfacial polymerization of immiscible hydrophilic and hydrophobic vinyl monomer solutions, and the resultant product exhibited binary cooperative shape transformation to multiple external stimuli. The Janus copolymer film can work in both aqueous solutions and organic solvents, with bidirectional and site-specific bending arising from cooperative asymmetric swelling/shrinking of the hydrogel and organogel networks. In addition, the as-prepared Janus copolymer film can act as a sensor element for solvent leakage detection. This binary cooperative strategy is applicable to most immiscible monomer systems and provides a general approach to developing novel functional copolymer materials. NPG Asia Materials (2017) 9, e380; doi:10.1038/am.2017.61; published online 19 May 2017 INTRODUCTIONThe shape transformations of biological organisms [1][2][3][4][5][6] have been the inspiration for many products in the field of artificial muscles, 7-13 soft robotics, 14-19 sensors 20 and complex shape engineering. 21,22 For example, the leaves of the Venus flytrap snap together to capture insects by virtue of the synergy between the hydroelastic instability and asymmetric expansion of the inner and outer surfaces at the cellular level. 2 The layered anisotropic orientated cellulose fibrils induce hygroscopic movements of pine cones, 1 wheat awns, 3 orchid tree seedpods 6 and other plants. By mimicking the sophisticated hierarchical structures present in nature, the motion of polymer films has been successfully demonstrated in several cases. [23][24][25][26][27][28][29][30] For example, hydrogel bilayers embedded with intersecting inorganic platelets or cellulose fibrils have exhibited pine-cone-like bending and pod-like twisting motions. 24,31 However, the practical applications of these actuators were limited because of the low modulus and weak mechanical strength of the hydrogels. 32 Elastomer single layer films, such as azobenzene polymer films synthesized using an elaborate molecular design, 13,27 can achieve smart responsive curving. However, these films require a unidirectional stimulus to generate anisotropic contraction/expansion of their two sides; this factor limits the film thickness to the micrometer or sub-millimeter level. 27,[33][34][35] Therefore,

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“…On the other hand, the hygroscopic movements of pine cones 24 and ice plant seed capsules 22 , although slower, can function even when the host organisms are dead. Recently, enormous efforts have been paid to these bio-prototypes, with progress being made on responsive nanocomposites and surfaces 3 , energy generators and transducers 25,26 , programmable origami 27 , soft robotics [28][29][30] , smart gels [31][32][33] and artificial muscles [34][35][36] . Yet, most of the polymer actuators suffer from the relatively slow and small scale movements; furthermore, they are susceptible to severe circumstances and involve complex preparation such as multistep lithographic processes 21,37 .…”

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confidence: 99%

An instant multi-responsive porous polymer actuator driven by solvent molecule sorption

et al. 2014

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Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20°C) at a speed of an order of magnitude faster than the state-ofthe-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-tomake and survives even after hydrothermal processing (200°C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn 'inert' objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.

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Hierarchical Multi‐Step Folding of Polymer Bilayers

Cited by 148 publications

References 22 publications

Directed Motility of Hygroresponsive Biomimetic Actuators

Directed Motility of Hygroresponsive Biomimetic Actuators

A monolithic hydro/organo macro copolymer actuator synthesized via interfacial copolymerization

An instant multi-responsive porous polymer actuator driven by solvent molecule sorption

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