Ultrafast yet controllable dual-responsive all-carbon actuator for

Subscriber access provided by MIDWESTERN UNIVERSITY

Functional Nanostructured Materials (including low-D carbon)

Ultrafast yet controllable dual-responsive all-carbon actuator for implementing unusual mechanical movements Hao Li, and Jianfeng Wang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b22099 • Publication Date (Web): 22 Feb 2019 Downloaded from http://pubs.acs.org on February 22, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Ultrafast yet Controllable Dual-Responsive AllCarbon Actuator for Implementing Unusual Mechanical Movements Hao Li, and Jianfeng Wang* Hunan Province Key Laboratory of Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University, Changsha 410082, China KEYWORDS: all-carbon actuators, dual response, ultrafast speed, controllable deformation, mechanical movements

ABSTRACT: Synthetic soft actuators with the integration of fast response speed, large-scale displacement and precise control over deformation direction are highly demanded for implementing agile and precise mechanical movements in smart robots, artificial muscles and biomimetic devices. In this work, ultrafast yet controllable all-carbon actuators are created based on graphene oxide and oriented carbon nanotubes. This all-carbon actuator shows humidity- and near infrared light-induced actuation with unprecedented performance integration, including ultrafast response (0.08 s), ultralarge deformation (angel change per length 70 o/mm), on-demand control over deformation direction (directional bending and chiral twisting) and high reversibility (no detectable fatigue after 10000 cycles). Impressively, the remarkable actuation performances allow the all-carbon actuator to implement diverse unusual movements, including light-triggered jumping vertically at a speed of 250 mm/s, rolling horizontally at a speed of 12 mm/s, throwing

ACS Paragon Plus Environment

1

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 26

object at a speed of 505 mm/s, arresting high-speed object (335 mm/s), as well as humiditytriggered lifting object instantly (0.34 s).


2

Page 3 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Synthetic soft actuators which can implement agile and precise mechanical movements in response to external stimuli (e.g., light,1-11 heat,12-15 and humidity16-22) are being eagerly sought in the field of smart robots, artificial muscles and biomimetic devices.23, 24 Some plant actuators exhibit extreme motion output for survival, which is difficult to be achieved in synthetic counterparts.25 For example, mimosa folds up its leaves in 0.5 s by osmotically driven cellular water loss after touch stimulation.26 Noose-like carnivorous fungus traps nematodes in less than 0.1 s by swelling rapidly.27 Venus ﬂytrap snaps their two pieces of leaves together in one tenth of a second by controlling elastic instability to capture insects accurately.28 Physically, these extreme motion outputs arise from multiple indispensable factors, including fast response speed, large-scale displacement and precise control over deformation direction. For synthetic swelling/shrinking actuators, response time is generally long from several seconds to several minutes because of slow solvent transport. Recently, some efforts have been made to shorten the bending time through designing specific microstructure within bilayer or gradient materials for facilitating moisture/water diffusion. Porous foam is bent non-directionally, generating a bending angle per length of 54o within 0.3 s.29 Loose electrospun fibrous mat is bent into a ring within 0.984 s.30 Impressively, thin layered microstructure, sensitive to fluctuation in ambient humidity, is randomly bent into one curl in 0.05 s, so that it exhibits unusual mechanical motion with being able to jump instantly.31 On the other hand, some efforts have been made to control over the bending direction through designing oriented microstructure or stripe patterns with being swollen/shrunk anisotropically.32 Hydrogel containing site-specifically oriented inorganic platelets is directionally bent and twisted with time in the range of several minutes and several hours.33 Pine cone-inspired polymer bilayer containing oriented carbon nanotubes is


3


Page 4 of 26

directionally bent in about one second.34 Stripe hydrogel with compositional gradient is twisted into chiral helix within two hours.35 Although some progress has been made to boost actuation speed or control over actuation direction, in only very cases artificial actuators with excellent integration of the two aspects are obtained.36, 37 Moreover, artificial film actuator with being able to implement directional extreme motions is still not achieved so far. It is reported that submicrometer-thick graphene oxide (GO) film allows unimpeded permeation of water because of fast diffusion of water molecules through two-dimensional capillaries between stacked hydrophilic GO sheets.38 In addition, oriented fiber could impose anisotropic constraint on the deformation of hygroscopic polymer.39 In this study, we, for the first time, develop a humidity- and light-responsive all-carbon actuator composed of a hydrophilic GO layer and a less hydrophilic oriented CNT layer. Due to fast absorption/desorption of water molecules from GO layer and anisotropic deformation constraint of oriented CNT on GO layer, the dual-responsive all-carbon actuator exhibits ultrafast, as little as 0.08 s, yet directional controlled bending and twisting with large-scale displacement. The remarkable actuation is highly reversible without detectable fatigue after 10000 cycles. The allcarbon actuator is successfully employed to implement diverse unusual mechanical movements, demonstrated as jumping vertically, fast rolling horizontally, throwing object slantwise, capturing high-speed object and lifting object instantly. Such robust actuation readily lends the all-carbon actuator to integration in a diverse variety of applications, such as artificial muscles, biomimetic devices, high-speed motors and smart robots. RESULTS AND DISCUSSION The all-carbon GO-CNT actuator was fabricated via a facile three-step process, as shown in Figure 1A. First, continuous oriented CNT sheet was drawn from CNT array and paved on a


4

Page 5 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


filter membrane.40 Then, GO was deposited onto CNT sheet through vacuum-assisted filtration, leading to a black GO-CNT bilayer film (Figure 1B). In the bilayer film, the thickness of CNT layer and GO layer was about 0.15 µm and 0.65 µm, respectively. The bilayer film exhibits slightly anisotropic mechanical property with a high tensile strength of 125 MPa along CNT orientation and a relative low strength of 103 MPa perpendicular to CNT orientation (Supporting Information, Figure S1). Finally, the bilayer film was cut into rectangular strips along different directions relative to CNT orientation. Four types of GO-CNT actuators were obtained, in which the angle (α) between CNT orientation and the longitudinal direction of strip was 0°, 45°, 90° and 135°. The four actuators are denoted as strip-0°, strip-45°, strip-90° and strip-135o respectively. We used SEM, contact angle measurement and X-ray photoelectron spectroscopy (XPS) to characterize the microstructure and surface property of GO-CNT actuator. Figure 1C shows its surface SEM image on the side of CNT layer. It is observed that CNTs are well aligned along film plane. It exhibits slight hydrophilicity with water contact angle of 74°. XPS analysis reveals that, besides predominant carbon element, the CNT layer contains little oxygen. The C/O atomic ratio is 14:1 (Figure 1E). The C1s spectrum analysis reveals three types of carbon-containing bonds: C-C (284.8 eV), C-O (286.8 eV) and C=O (288.2 eV). The surface on the side of GO layer exhibits many random wrinkles, arising from the local folding of ultrathin flexible GO sheets (Figure 1D). Its water contact angle is 34°, obviously lower than the CNT layer. The high hydrophilicity is due to their abundant oxygen-containing groups. The C/O atomic ratio is 2:1 (Figure 1F). The C1s spectrum analysis reveals four types of carbon-containing bonds: C-C (284.8 eV), C-O (286.8 eV), C=O (288.2 eV) and O-C=O (288.6 eV).


5


Page 6 of 26

The asymmetric hydrophilicity imparts the GO-CNT actuator with deformation ability in responsive to the increase of humidity. The actuation process of four actuators with different α angles (strip-0°, strip-90°, strip-45°and strip-135°) was recorded by a digital video camera and investigated using frame-by-frame analysis, as shown in Figure 2A-D and Movie S1. Surprisingly, all actuators exhibited extremely fast deformation within 0.08~0.17 s. This is related to the hydrophilicity of GO nanosheet and unimpeded permeation of water molecules through the gap between GO nanosheets.38 Their deformation direction strongly depended on α angles. Flat strip-0°and strip-90°were bent toward CNT layer along long side and short side into ring and tube, respectively. Interestingly, flat strip-45°and strip-135°were twisted directionally toward CNT layer into right-handed helix and left-handed helix, respectively. Furthermore, these deformations were highly reversible. Once humidity was decreased, all actuators restored to initial flat state immediately (Supporting Information, Figure S2). The bending or twisting angles with time in one cycle are shown in Figure 2E. The maximum bending angle was 360o for strip0o and 350o for strip-90o. The maximum twisting angle was 720o for strip-45o and 540o strip-135o. The magnitude of maximum deformation was highly tunable through humidity (Supporting Information, Figure S3). In addition, all actuators had excellent cyclic stability. No detectable decrease in deformation angle was observed, even after 10000 cycles (Figure 2F). We compare the deformation angle per length and actuation time of our actuator with previously reported humidity-driven actuators and other fast actuators (Figure 2G and Supporting Information, Table S1). It is found that the deformation angle per length of our actuator surpasses the most of reported actuators. Furthermore, the response time (0.08 s) is much shorter than normal humidity-driven actuators. It is also superior to some reported fast actuators, including humidity-driven porous foam (0.3 s),29 humidity-driven GO-containing


6

Page 7 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


bilayer film (0.5 s),41 temperature-driven electrospun fibrous mat (0.984 s),20 and is even comparable to some fast swelling/shrinking plant actuators and snap-buckling plant actuators in nature, such as mimosa (0.5 s)26 carnivorous fungus (~ 0.1 s),27 and Venus flytrap (0.1 s)28 (Supporting Information, Figure S4). Importantly, such marvelous combination of ultrafast actuation speed, ultralarge actuation amplitude and controllable deformation is rarely achieved in previous reports.37 Besides humidity-driven actuation, the GO-CNT bilayer has excellent actuation performances by NIR light, due to that both CNT and GO have high absorption of NIR light and high efficiency of thermal transformation.42, 43 The converted heat causes rapid desorption of water molecules from GO layer and thus drives the GO-CNT bilayer to deform instantaneously. The NIR light-driven fast deformation is shown in Figure 3A-D and Movie S2. Once irradiated by light, flat strip-0o and strip-90o were bent toward GO layer along long side and short side into ring and tube, while strip-45o and strip-135o were twisted directionally toward GO layer into lefthanded helix and right-handed helix. These bending and twisting deformations were completed within 0.2~0.24 s. After light irradiation stopped, the GO layer absorbed water molecules again from surrounding environment. As a result, the actuators restored from bending and twisting shape to initial flat state (Supporting Information, Figure S5). In one cycle, the bending and twisting angles were extracted through frame-by-frame analysis of video. The angle-time curve is shown in Figure 3E. Strip-0o and strip-90o had maximum bending angles of 360o and 350o. Strip-45o and strip-135o exhibited maximum twisting angles of 630o and 700o. The maximum deformation angle was highly tunable through increasing light power density, as shown in Supporting Information, Figure S6. In addition, the light-driven bending and twisting was highly reversible with no observable degradation in 10000 cycles (Figure 3F).


7


Page 8 of 26

We compare the deformation angles per length and actuation time of our actuators with previously reported light-driven GO-containing actuators, CNT-containing actuators and other light-driven actuators (Figure 3G and Supporting Information, Table S2). It is found that the deformation angles per length surpasses most light-driven actuators. Remarkably, the actuation time is far superior to all light-driven carbon-based actuators.44 Importantly, such combination of ultrafast response speed, large actuation amplitude and controllable deformation in response to light is not achieved in previous reports. The deformation of GO-CNT actuator in response to NIR light is closely related to different photothermal shrinkage of CNT layer and GO layer, and anisotropic mechanical properties of CNT layer. The two factors cause anisotropic strain mismatch of CNT layer and GO layer, which promotes the controllable deformation of the actuators. When NIR light was applied, CNT layer was shrunk by 0.4% vertical to CNT orientation, while it was only shrunk by 0.08% along CNT orientation (Figure 4A). The anisotropic shrinkage is attributed to its anisotropic elastic modulus. CNT layer had a modulus of 30.11 GPa along CNT orientation, two orders of magnitude higher than that vertical to CNT orientation (0.16 GPa) (Figure 4B). The high modulus restrained CNT layer from shrinking along CNT orientation. For GO layer, NIR light irradiation caused isotropic shrinkage (Figure 4C). Mechanical property measurement showed that GO layer had isotropic modulus of 8.14 GPa, due to its inherent two-dimensional geometry (Figure 4D). The shrinkage was up to 1.15%, obviously larger than CNT layer. The large shrinkage arose from strong dehydration within water-rich GO layer, which had much more oxygen-containing groups than CNT layer (Figure 1C-F). Therefore, the strain difference between CNT layer and GO layer along CNT orientation (GO∥﹣CNT∥=1.07%) was larger than that vertical to CNT orientation (GO⊥﹣CNT⊥=0.75%). As a result, the strip-0o is bent substantially along CNT toward GO layer


8

Page 9 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(Figure 4E and Figure 3A). For strip-90o, strip-45o and strip-135o, bending along CNT toward GO layer leads to tube, left-handed cylinder helix and right-handed cylinder helix with CNT being on the outside and aligned along circumference of final geometric structures (Figure 3B-D). In contrast to NIR light-induced dehydration shrinkage, humidity causes hygroexpansion of GO-CNT actuator. CNT layer swelled anisotropically, in which the strain vertical to CNT orientation was larger than that along CNT orientation (Supporting Information, Figure S7). GO layer swelled isotropically with strain being larger than that of CNT layer. The expansion strain difference between CNT layer and GO layer along CNT orientation (GO∥﹣CNT∥) was much larger than that vertical to CNT orientation (GO⊥﹣CNT⊥). The large strain mismatch allows the actuator to be bent substantially along CNT toward CNT layer. As a result, strip-0o, strip-90o, strip-45o and strip-135o are transformed into ring, tube, right-handed cylinder helix and lefthanded cylinder helix with CNT being in the inside and aligned along circumference of final geometric structures (Figure 2A-D). The ultrafast yet controllable actuation allows the GO-CNT actuator to implement unusual motion output in response to humidity and NIR light. A strip-0o with a length of 17 mm and a width of 4 mm was put on a piece of paper with GO layer being downward. Once NIR light was applied, the long strip started to bend at two ends and was evolved into “M” shape structure within 0.08 s. In this process, the strip height increased linearly at a speed of 25 mm/s with elastic energy being accumulated gradually. Then, the “M” shape structure was suddenly switched upward into arc structure at a higher speed of 75 mm/s because the accumulated elastic energy was released instantaneously. Once the strip was away from paper substrate, it accelerated at a speed of 250 mm/s because of absence of friction force, and finally reached a


9


Page 10 of 26

maximum height of 8 mm in 0.14 s (Figure 5A, Movie S3 and Supporting Information, Figure S8). The second demonstration of unusual motion output is light-driven rapid rolling (Figure 5B and Movie S4). A strip-0o was assembled into an 8 mm-diameter ring with GO layer being outside. Once the ring was irradiated from upper left by NIR light, the curvature of irradiated region was decreased, which caused the center of gravity to shift forward. As a result, the ring rolled rapidly for 62 mm in 5.2 s, corresponding to an average velocity of 12 mm/s. The third demonstration is to throw object (Figure 5C and Movie S5). A plastic ball was placed at the lower end of strip-0o. Once irradiated by NIR light, the strip carried the ball to bend upward. At that moment of separation from strip, the ball moved obliquely at a speed of 505 mm/s, and finally stopped at 23 mm away from its initial position (Supporting Information, Figure S9). The fourth demonstration is to arrest high-speed object (Figure 5D and Movie S6). A suspended plastic bulk moved at a speed of 335 mm/s and passed right above an assembled cross-shaped gripper. Light triggered the gripper to bend instantly for catching the plastic bulk. Finally, rapid energy output was demonstrated in humidity-driven GO-CNT actuator. A plastic cargo was mounted at one end of strip-45o with a weight of 0.3 mg. Once humidified, the strip-45o was instantaneously twisted into right-handed helix and lifted the cargo, 23 times heavier than the strip, for 12 mm in 0.34 s, corresponding to a calculated power density of 7.84 W/kg (Figure 5E and Movie S7). CONCLUSIONS In summary, ultrafast yet controllable dual-driven GO-CNT actuators were created based on GO and oriented CNT through a facile, flexible fabrication process. Multiple types of large-size, reversible deformation in response to humidity and NIR light were achieved, from two-


10

Page 11 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


dimensional directional bending to three-dimensional chiral twisting, all of which are guided by pre-programmed CNT orientations. Only 0.08~0.24 s these deformations require, obviously superior to previously reported various actuators and comparable to some ultrafast actuators in nature. The combination of ultrafast actuation speed, large actuation amplitude and controllable actuation styles allow the actuators to jump vertically, fast roll horizontally, throw, catch and lift objects instantaneously. The integration of multiple outstanding properties makes the GO-CNT actuator a great candidate for applications in artificial muscles, biomimetic devices, high-speed motors and smart robots. METHODS Materials: Drawable carbon nanotube array was grown on a silicon wafer by using chemical vapor deposition. Graphene oxide dispersion (CAS: 7440-44-0) was purchased from Nanjing XFNANO Materials Tech Co., Ltd. CH3COOK, MgCl2, NaBr, NaCl, K2CO3, KCl, and K2SO4 were obtained from Sinopharm Chemical Reagent Co., Ltd. Fabrication of GO-CNT actuators: First, 5-cm-wide oriented CNT sheet was drawn from CNT array by a glass rod and paved onto a PTFE filtration membrane (0.1 μm in pore size) through a layer-by-layer fashion. After four layers of CNT sheet were paved, it was condensed with ethanol by vacuum filtration for 3 min. Then, GO was deposited onto the condensed CNT through vacuum filtration of diluted GO dispersion (0.5 mg/ml, 10 ml) for 2 h. After dried overnight at room temperature and 56% relative humidity, the GO-CNT film was peeled off and cut into strips along different directions. The angle between CNT orientation and long side of strip is 0o, 45o, 90o and 135o. The four actuators are denoted as strip-0o, strip-45o, strip-90o and strip-135o, respectively.


11


Page 12 of 26

Characterizations: Scanning electron microscope (SEM) images were obtained by a field emission scanning electron microscope (Hitachi S-4800). X-ray photoelectron spectroscopy (XPS) was recorded on an ESCALAB250Xi photoelectron spectrometer (ThermoFisher-VG Scientific) with Al Kα (1486.6 eV). Stereomicroscope (TY-WB47) was used to monitor the size change of pure GO and CNT films in response to NIR light. The water contact angles were measured on an OCA 20 machine (Data Physics, Germany). Tensile property was conducted with an AGS-X testing system (Shimadzu). Humidity-driven actuation measurement: The sizes of strip-0o, strip-45o, strip-90o and strip135o for Humidity-driven actuation measurement are 23 mm × 3.5 mm, 20 mm × 4 mm, 15 mm × 5 mm and 20 mm × 4 mm, respectively. For the measurement of humidity-driven deformation and recovery, the GO-CNT sample was clamped by a fixed tweezer and placed above a waterfilled glass dish. The humidity of sample was controlled to be 80% through adjusting the vertical distance between sample and water surface. After that, the water-filled glass dish was moved along horizon direction to be close to and away from sample. The deformation process was recorded using a single-lens reflex camera (FDR-AX700, SONY). The timing for humiditydriven bending and twisting began with the initial deformation of samples. For the measurement of dependence of deformation angle on relative humidity, the GO-CNT sample and a hygrometer was placed in a closed glass vessel for one day, which contained saturated aqueous solutions of CH3COOK, MgCl2, NaBr, NaCl, K2CO3, KCl or K2SO4. These saturated aqueous solutions yielded 25%, 36%, 50%, 66%, 75%, 82%, and 97% RH, respectively. NIR light-driven actuation measurement: The sizes of strip-0o, strip-45o, strip-90o and strip135o for NIR light-driven actuation measurement are 13 mm × 5 mm, 20 mm × 4 mm, 15 mm × 5 mm and 20 mm × 4 mm, respectively. For the measurement of NIR light-driven deformation


12

Page 13 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


and recovery, the GO-CNT sample was clamped by a fixed tweezer and placed below a NIR light resource. The power density of light around sample was controlled to be 300 mW/cm 2 through adjusting the distance between sample and light resource. Light-driven deformation and recovery were carried out through turning on and off the light resource. The deformation process was recorded using a single-lens reflex camera (FDR-AX700, SONY). The timing for NIR lightdriven bending and twisting began with the initial deformation of samples. For the measurement of dependence of deformation angle on power density, the GO-CNT sample was placed at different distance from NIR-light resource. The light power density was recorded by an infrared power meter (LH-129, Shenzhen Lian Hui Cheng Technology Co. Ltd.).


13


Figures

A

B 0º vacuum

90º

a

1 cm

D

1 μm 74o

E

50 μm

C-C 284.8 eV C-O 286.8 eV C=O 288.2 eV

F

C-C 284.8 eV C-O 286.8 eV C=O 288.2 eV COOH 288.6 eV

C

O

284

288

292

296

Intensity

C

Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 26

O C 284

288

292

296

34o 400

800

1200

Binding Energy (eV)

400

800

1200

Binding Energy (eV)

Figure 1. Fabrication and structure of GO-CNT bilayer actuators. (A) Fabrication procedures, including the drawing of oriented CNT film from array, vacuum-assisted filtration of GO solution and the cutting of GO-CNT film into strips. The angle between CNT orientation and the length direction of strip is defined as α. (B) Photo of as-prepared GO-CNT film. (C) SEM image of the CNT surface and the contact angle of water on CNT layer. (D) SEM image of the GO surface and the contact angle of water on GO layer. (E) Wide range XPS curve of CNT layer, showing a high C/O atomic ratio of 14:1. The inset is C1s peak. (F) Wide range XPS curve of GO layer, showing a low C/O atomic ratio of 2:1. The inset is C1s peak.


14

Page 15 of 26

A

0s

0.06 s

0.12 s

0.16 s

B

0s

0.02 s

0.04 s

0.08 s

C

0s

0.06 s

0.12 s

0.17 s

D

0s

0.06 s

0.12 s

0.17 s

400

G 80

400 a=0° a=45°

200

200 0

800 600

Angle (°)

600

F

a=90° a=135°

0.5

1.0

1.5

Time (s)

2.0

Our actuator Porous foam GO-containing bilayer Electrospun mat Humidity-driven actuators

60

o

a=0° a=45°

Angle / length( /mm)

E 800

Angle (°)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0

1

10

a=90° a=135°

100

1000

10000

Cycle number

40 20 0 0.1

1

10

100

1000

Time (s)

Figure 2. Humidity-driven deformation of GO-CNT actuators. (A-D) The real time actuation images of the actuators with different α values (A: strip-0o, B: strip-90o, C: strip-45o, D: strip135o) in response to humidity change from 56% to 80%. (E) Dependence of their deformation angles on operation time in one cycle. The rising part of curves corresponds to the sample actuated at 80% humidity. The descending part of curves corresponds to the sample restored at 56% humidity. (F) Dependence of their deformation angles on cycle number. (G) Ashby-like plot for comparison of our actuator with previously reported humidity-driven actuators and other fast actuators, including porous foam, GO-containing bilayer film, electrospun fibrous mat. The comparison directly shows that our actuator realizes the integration of ultrafast speed and large deformation angle per length.


15


A

0s

0.07 s

0.14 s

0.2 s

B

0s

0.08 s

0.16 s

0.24 s

C

0s

0.08 s

0.16 s

0.22 s

D

0s

0.07 s

0.15 s

0.23 s

a=0° a=45°

400 200 0

F

800

G

600

Angle (°)

600

a=90° a=135°

400 a=0° a=45°

200

0

1

2

3

Time (s)

4

80 Our actuator GO-based actuators CNT-based actuators Other light-driven actuators

60

o

800

Angle / length( /mm)

E

Angle (°)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 26

0

1

10

100

a=90° a=135°

1000

10000

Cycle number

40 20 0 0.1

1

10

100

1000 10000

Time (s)

Figure 3. NIR light-driven deformation of GO-CNT actuators. (A-D) The real time actuation images of the actuators with different α values (A: strip-0o, B: strip-90o, C: strip-45o, D: strip135o) in response to NIR light irradiation with an intensity of 300 mW/cm2. (E) Dependence of their deformation angles on operation time in one cycle. The rising part of curves corresponds to the sample actuated by NIR light (300 mW/cm2). The descending part of curves corresponds to the sample restored without irradiation of NIR light. (F) Dependence of their deformation angles on cycle number. (G) Ashby-like plot for comparison of our actuator with previously reported light-driven actuators, including GO-based actuators, CNT-based actuators and other types of actuators. The comparison shows that our actuators have ultrafast speed and large deformation per length concurrently.


16

off

off

on

B

on

1200 1000 800 600

10 8 6 4 2 0 0

Stress (MPa)

A

400

E CNT⊥ 1 2 3 Strain (%)

4

0.5

1.0

CNT∥

200 0 -0.5

Light on 0.0

1.5

2.0

Strain (%)

Light off

C

off

off

on

on

D Stress (MPa)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Stress (MPa)

Page 17 of 26

150 120 90

CNT

60

GO∥ GO⊥

GO

30 0 0

H2O 1

2

3

4

5

Strain (%)

Figure 4. Deformation mechanism of GO-CNT actuator in response to NIR light irradiation. (A) Optical images of CNT film (1 cm × 1 cm) without and with irradiation, showing anisotropic shrinkage in response to NIR light. The CNT film was shrunk by 40 μm perpendicular to CNT orientation and by 8 μm along CNT orientation. White arrows represent the orientation direction of CNT. Scale bars are 200 μm. (B) Typical tensile stress-strain curves of CNT film, showing anisotropic mechanical properties. The mechanical property along CNT orientation is much higher than that perpendicular to CNT orientation. (C) Optical images of GO film (1 cm × 1 cm) without and with irradiation, showing isotropic shrinkage of about 115 μm. Scale bars are 200 μm. (D) Typical tensile stress-strain curves of GO film, showing isotropic mechanical properties. (E) Schematic illustration of the bending/unbending deformation behaviors of the actuator in response to NIR light irradiation. NIR light irradiation causes large isotropic shrinkage of GO layer, while CNT layer generates anisotropic shrinkage. Red arrows represent shrinkage direction and amplitude.


17


A

0s

0.08 s

B

0s

1.8 s

C

0s

0.02 s

Page 18 of 26

D

0s

E

0s

0.06 s 0.16 s

0.1 s

3.6 s

0.04 s

0.12 s D

0.34 s 0.14 s

5.2 s

0.18 s

0.22 s

Figure 5. Demonstrations of the ultrafast yet controllable dual-driven GO-CNT actuators for implementing unusual mechanical motions. (A) Light-triggered abrupt jumping of strip-0o, showing a maximum height of 8 mm in 0.14 s. The black arrows denote movement direction. (B) Light-driven fast rolling of GO-CNT ring made of strip-0o, corresponding to an average velocity of 12 mm/s. (C) Light-driven throwing of plastic ball by strip-0o, showing a movement distance of 23 mm in 0.18 s. (D) Light-driven arresting of high-speed moving plastic bulk by an assembled cross-shaped strip-0o. (E) Humidity-driven instantaneous twisting of strip-45o for lifting object, showing the raise of a plastic cargo, 23 times heavier than the strip, for 12 mm in 0.34 s.


18

Page 19 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


ASSOCIATED CONTENT Supporting Information is available free of charge. Supplementary text, figures and table (PDF) Movie S1: Humidity-driven actuation of GO-CNT actuators (AVI) Movie S2: NIR light-driven actuation of GO-CNT actuators (AVI) Movie S3: Light-triggered abrupt jumping of strip-0o (AVI) Movie S4: Light-driven fast rolling of GO-CNT ring made of strip-0o (AVI) Movie S5: Light-driven throwing of plastic ball by strip-0o (AVI) Movie S6: Light-driven arresting of high-speed moving plastic bulk by an assembled crossshaped strip-0o (AVI) Movie S7: Humidity-driven instantaneous twisting of strip-45o for lifting object (AVI) AUTHOR INFORMATION Corresponding Author * E-mail: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT The authors acknowledge the financial support from High-Level Talent Gathering Project in Hunan Province (2018RS3055) and Fundamental Research Funds for the Central Universities.


19


Page 20 of 26

REFERENCES (1)

Zhang, X.; Yu, Z.; Wang, C.; Zarrouk, D.; Seo, J. W.; Cheng, J. C.; Buchan, A. D.; Takei,

K.; Zhao, Y.; Ager, J. W.; Zhang, J.; Hettick, M.; Hersam, M. C.; Pisano, A. P.; Fearing, R. S.; Javey, A. Photoactuators and Motors Based on Carbon Nanotubes with Selective Chirality Distributions. Nat. Commun. 2014, 5, 2983-2991. (2)

Hu, Y.; Liu, J.; Chang, L.; Yang, L.; Xu, A.; Qi, K.; Lu, P.; Wu, G.; Chen, W.; Wu, Y.

Electrically and Sunlight-Driven Actuator with Versatile Biomimetic Motions Based on Rolled Carbon Nanotube Bilayer Composite. Adv. Funct. Mater. 2017, 27, 1704388. (3)

Sun, X.; Wang, W.; Qiu, L.; Guo, W.; Yu, Y.; Peng, H. Unusual Reversible

Photomechanical Actuation in Polymer/Nanotube Composites. Angew. Chem., Int. Ed. 2012, 51, 8520-8524. (4)

Wang, E.; Desai, M. S.; Lee, S. W. Light-Controlled Graphene-Elastin Composite

Hydrogel Actuators. Nano Lett 2013, 13, 2826-2830. (5)

Jiang, Z.; Xu, M.; Li, F.; Yu, Y. Red-Light-Controllable Liquid-Crystal Soft Actuators via

Low-Power Excited Upconversion Based on Triplet-Triplet Annihilation. J. Am. Chem. Soc. 2013, 135, 16446-16453. (6)

Tai, Y.; Lubineau, G.; Yang, Z. Light-Activated Rapid-Response Polyvinylidene-

Fluoride-Based Flexible Films. Adv. Mater. 2016, 28, 4665-4670. (7)

Lahikainen, M.; Zeng, H.; Priimagi, A. Reconfigurable Photoactuator Through

Synergistic Use of Photochemical and Photothermal Effects. Nat. Commun. 2018, 9, 4148-4156. (8)

Takashima, Y.; Hatanaka, S.; Otsubo, M.; Nakahata, M.; Kakuta, T.; Hashidzume, A.;

Yamaguchi, H.; Harada, A. Expansion-Contraction of Photoresponsive Artificial Muscle Regulated by Host-Guest Interactions. Nat. Commun. 2012, 3, 1270-1278.


20

Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(9)

Van Oosten, C. L.; Bastiaansen, C. W.; Broer, D. J. Printed Artificial Cilia from Liquid-

Crystal Network Actuators Modularly Driven by Light. Nat. Mater. 2009, 8, 677-682. (10)

Iwaso, K.; Takashima, Y.; Harada, A. Fast Response Dry-Type Artificial Molecular

Muscles with [c2]Daisy Chains. Nat. Chem. 2016, 8, 625-632. (11)

Wani, O. M.; Zeng, H.; Priimagi, A. A light-Driven Artificial Flytrap. Nat. Commun.

2017, 8, 15546-15553. (12)

Chen, T.; Bakhshi, H.; Liu, L.; Ji, J.; Agarwal, S. Combining 3D Printing with

Electrospinning for Rapid Response and Enhanced Designability of Hydrogel Actuators. Adv. Funct. Mater. 2018, 28, 1800514. (13)

Wang, C.; Wang, Y.; Yao, Y.; Luo, W.; Wan, J.; Dai, J.; Hitz, E.; Fu, K. K.; Hu, L. A

Solution-Processed High-Temperature, Flexible, Thin-Film Actuator. Adv. Mater. 2016, 28, 86188624. (14)

Kim, Y. S.; Liu, M.; Ishida, Y.; Ebina, Y.; Osada, M.; Sasaki, T.; Hikima, T.; Takata, M.;

Aida, T. Thermoresponsive Actuation Enabled by Permittivity Switching in an Electrostatically Anisotropic Hydrogel. Nat. Mater. 2015, 14, 1002-1009. (15)

Chin, S. M.; Synatschke, C. V.; Liu, S.; Nap, R. J.; Sather, N. A.; Wang, Q.; Alvarez, Z.;

Edelbrock, A. N.; Fyrner, T.; Palmer, L. C.; Szleifer, I.; Olvera de la Cruz, M.; Stupp, S. I. Covalent-Supramolecular Hybrid Polymers as Muscle-Inspired Anisotropic Actuators. Nat. Commun. 2018, 9, 2395-2406. (16)

Chen, X.; Mahadevan, L.; Driks, A.; Sahin, O. Bacillus Spores as Building Blocks for

Stimuli-Responsive Materials and Nanogenerators. Nat. Nanotechnol. 2014, 9, 137-141. (17)

Weng, M.; Zhou, P.; Chen, L.; Zhang, L.; Zhang, W.; Huang, Z.; Liu, C.; Fan, S.

Multiresponsive Bidirectional Bending Actuators Fabricated by a Pencil-on-Paper Method. Adv.


21


Page 22 of 26

Funct. Mater. 2016, 26, 7244-7253. (18)

De Haan, L. T.; Verjans, J. M. N.; Broer, D. J.; Bastiaansen, C. W. M.; Schenning, A. P.

H. J. Humidity-Responsive Liquid Crystalline Polymer Actuators with an Asymmetry in the Molecular Trigger That Bend, Fold, and Curl. J. Am. Chem. Soc. 2014, 136, 10585-10588. (19)

Han, D.; Zhang, Y.; Liu, Y.; Liu, Y.; Jiang, H.; Han, B.; Fu, X.; Ding, H.; Xu, H.; Sun, H.

Bioinspired Graphene Actuators Prepared by Unilateral UV Irradiation of Graphene Oxide Papers. Adv. Funct. Mater. 2015, 25, 4548-4557. (20)

Cheng, H.; Liu, J.; Zhao, Y.; Hu, C.; Zhang, Z.; Chen, N.; Jiang, L.; Qu, L. Graphene

Fibers with Predetermined Deformation as Moisture-Triggered Actuators and Robots. Angew. Chem., Int. Ed. 2013, 52, 10482-10486. (21)

Mu, J.; Wang, G.; Yan, H.; Li, H.; Wang, X.; Gao, E.; Hou, C.; Pham, A. T. C.; Wu, L.;

Zhang, Q.; Li, Y.; Xu, Z.; Guo, Y.; Reichmanis, E.; Wang, H.; Zhu, M. Molecular-Channel Driven Actuator with Considerations for Multiple Configurations and Color Switching. Nat. Commun. 2018, 9, 590-600. (22)

Zhang, L.; Liang, H.; Jacob, J.; Naumov, P., Photogated Humidity-Driven Motility. Nat.

Commun. 2015, 6, 7429-7440. (23)

Hu, Y.; Li, Z.; Lan, T.; Chen, W. Photoactuators for Direct Optical-to-Mechanical Energy

Conversion: From Nanocomponent Assembly to Macroscopic Deformation. Adv. Mater. 2016, 28, 10548-10556. (24)

Zhao, Y.; Song, L.; Zhang, Z.; Qu, L. Stimulus-Responsive Graphene Systems Towards

Actuator Applications. Energy & Environ. Sci. 2013, 6, 3520-3536. (25)

Skotheim, J. M.; Mahadevan, L. Physical Limits and Design Principles for Plant and

Fungal Movements. Science 2005, 308, 1308-1310.


22

Page 23 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(26)

Weintraub, M. Leaf Movements in Mimosa Pudica L. New Phytol. 1952, 50, 357-382

(27)

Polonovski, M.; Jayle, M. Existence in the Blood Plasma of a Substance Hastening the

Peroxydasic Activity of the Hemoglobin. C.R. Soc. Biol. Paris 1938, 129, 457-460. (28)

Forterre, Y.; Skotheim, J. M.; Dumais, J.; Mahadevan, L. How the Venus Flytrap Snaps.

Nature 2005, 433, 421-425. (29)

Zhao, Q.; Dunlop, J. W.; Qiu, X.; Huang, F.; Zhang, Z.; Heyda, J.; Dzubiella, J.;

Antonietti, M.; Yuan, J. An Instant Multi-Responsive Porous Polymer Actuator Driven by Solvent Molecule Sorption. Nat. Commun. 2014, 5, 4293-4301. (30)

Jiang, S.; Liu, F.; Lerch, A.; Ionov, L.; Agarwal, S. Unusual and Superfast Temperature-

Triggered Actuators. Adv. Mater. 2015, 27, 4865-4870. (31)

Arazoe, H.; Miyajima, D.; Akaike, K.; Araoka, F.; Sato, E.; Hikima, T.; Kawamoto, M.;

Aida, T. An Autonomous Actuator Driven by Fluctuations in Ambient Humidity. Nat. Mater. 2016, 15, 1084-1089. (32)

Ionov, L. Hydrogel-Based Actuators: Possibilities and Limitations. Materials Today 2014,

17, 494-503. (33)

Erb, R. M.; Sander, J. S.; Grisch, R.; Studart, A. R. Self-Shaping Composites with

Programmable Bioinspired Microstructures. Nat. Commun. 2013, 4, 1712-1720. (34)

Deng, J.; Li, J.; Chen, P.; Fang, X.; Sun, X.; Jiang, Y.; Weng, W.; Wang, B.; Peng, H.

Tunable Photothermal Actuators Based on a Pre-programmed Aligned Nanostructure. J. Am. Chem. Soc. 2016, 138, 225-230. (35)

Wu, Z. L.; Moshe, M.; Greener, J.; Therien-Aubin, H.; Nie, Z.; Sharon, E.; Kumacheva,

E., Three-dimensional Shape Transformations of Hydrogel Sheets Induced by Small-Scale Modulation of Internal Stresses. Nat. Commun. 2013, 4, 1586-1593.


23


(36)

Page 24 of 26

Liu, L.; Jiang, S.; Sun, Y.; Agarwal, S. Giving Direction to Motion and Surface with

Ultra-Fast Speed Using Oriented Hydrogel Fibers. Adv. Funct. Mater. 2016, 26, 1021-1027. (37)

Wang, J.; Wang, J.; Chen, Z.; Fang, S.; Zhu, Y.; Baughman, R. H.; Jiang, L. Tunable,

Fast, Robust Hydrogel Actuators Based on Evaporation-Programmed Heterogeneous Structures. Chem. Mater. 2017, 29, 9793-9801. (38)

Nair, R. R.; Wu, H. A.; Jayaram, P. N.; Grigorieva, I. V.; Geim, A. K. Unimpeded

Permeation of Water Through Helium-Leak-Tight Graphene-Based Membranes. Science 2012, 335, 442-444. (39)

Zhang, L.; Chizhik, S.; Wen, Y.; Naumov, P. Directed Motility of Hygroresponsive

Biomimetic Actuators. Adv. Funct. Mater. 2016, 26, 1040-1053. (40)

Li, Q.; Liu, C.; Lin, Y.; Liu, L.; Jiang, K.; Fan, S. Large-Strain, Multiform Movements

from Designable Electrothermal Actuators Based on Large Highly Anisotropic Carbon Nanotube Sheets. ACS Nano 2015, 9, 409-418. (41)

Xu, G.; Zhang, M.; Zhou, Q.; Chen, H.; Gao, T.; Li, C.; Shi, G. A Small Graphene Oxide

Sheet/Polyvinylidene Fluoride Bilayer Actuator with Large and Rapid Responses to Multiple Stimuli. Nanoscale 2017, 9, 17465-17470. (42)

Robinson, J. T.; Tabakman, S. M.; Liang, Y.; Wang, H.; Casalongue, H. S.; Vinh, D.; Dai,

H. Ultrasmall Reduced Graphene Oxide with High Near-Infrared Absorbance for Photothermal Therapy. J. Am. Chem. Soc. 2011, 133, 6825-6831. (43)

Koerner, H.; Price, G.; Pearce, N. A.; Alexander, M.; Vaia, R. A. Remotely actuated

polymer

Nanocomposites-Stress-Recovery

of

Carbon-Nanotube-Filled

Thermoplastic

Elastomers. Nat. Mater. 2004, 3, 115-120. (44)

Han, B.; Zhang, Y.-L.; Chen, Q.-D.; Sun, H.-B. Carbon-Based Photothermal Actuators.


24

Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Adv. Funct. Mater. 2018, 28, 1802235.


25


Page 26 of 26

The table of contents entry

0.08 s


26

Ultrafast yet controllable dual-responsive all-carbon actuator for

Recommend Documents