共查询到20条相似文献，搜索用时 0 毫秒
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Arif M. Abdullah Xiuling Li Paul V. Braun John A. Rogers K. Jimmy Hsia 《Advanced functional materials》2020,30(14)
Self‐assembly of 3D structures presents an attractive and scalable route to realize reconfigurable and functionally capable mesoscale devices without human intervention. A common approach for achieving this is to utilize stimuli‐responsive folding of hinged structures, which requires the integration of different materials and/or geometric arrangements along the hinges. It is demonstrated that the inclusion of Kirigami cuts in planar, hingeless bilayer thin sheets can be used to produce complex 3D shapes in an on‐demand manner. Nonlinear finite element models are developed to elucidate the mechanics of shape morphing in bilayer thin sheets and verify the predictions through swelling experiments of planar, millimeter‐scaled PDMS (polydimethylsiloxane) bilayers in organic solvents. Building upon the mechanistic understandings, The transformation of Kirigami‐cut simple bilayers into 3D shapes such as letters from the Roman alphabet (to make “ADVANCED FUNCTIONAL MATERIALS”) and open/closed polyhedral architectures is experimentally demonstrated. A possible application of the bilayers as tether‐less optical metamaterials with dynamically tunable light transmission and reflection behaviors is also shown. As the proposed mechanistic design principles could be applied to a variety of materials, this research broadly contributes toward the development of smart, tetherless, and reconfigurable multifunctional systems. 相似文献
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Wenying Shi Shan He Min Wei David G. Evans Xue Duan 《Advanced functional materials》2010,20(22):3856-3863
The preparation of a highly oriented photoluminescent film of fluorescein (FLU) and 1‐heptanesulfonic acid sodium (HES) co‐intercalated in a layered double hydroxide (LDH) matrix by electrophoretic deposition (EPD) is reported, and its application as an optical pH sensor is demonstrated. The FLU‐HES/LDH films with thickness ranging from nanometer to micrometer on indium tin oxide substrates exhibite good c‐orientation of LDH platelets (the ab‐plane of the LDH platelets parallel to the substrate), as confirmed by X‐ray diffraction and scanning electron microscopy. Polarized luminescence of the film is observed with anisotropy value r = 0.29, resulting from the highly oriented FLU in the LDH gallery. Furthermore, the optical pH sensor with film thickness of 300 nm exhibits a broad linear dynamic range for solution pH (5.02–8.54), good repeatability (relative standard deviation (RSD) less than 1.5% in 20 consecutive cycles) and reversibility (RSD less than 1.5% in 20 cycles), high photostability and storage stability (ca. 95.2% of its initial fluorescence intensity remains after one month) as well as fast response time (2 s). Therefore, this work creates new opportunities for the preparation and application of LDH‐based chromophores in the field of optical sensors. 相似文献
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Maarten Jaspers Alan E. Rowan Paul H. J. Kouwer 《Advanced functional materials》2015,25(41):6503-6510
The mechanical properties of hydrogels are commonly modified by changing the concentration of the molecular components. This approach, however, does not only change hydrogel mechanics, but also the microstructure, which in turn alters the macroscopic properties of the gel. Here, the Hofmeister effect is used to change the thermoresponsiveness of polyisocyanide hydrogels. In contrast to previous Hofmeister studies, the effect is used to change the phase transition temperatures and to tailor the mechanics of the thermoresponsive (semiflexible) polymer gels. It is demonstrated that the gel stiffness can be manipulated over more than two orders of magnitude by the addition of salts. Surprisingly, the microstructure of the gels does not change upon salt addition, demonstrating that the Hofmeister effect provides an excellent route to change the mechanical properties without distorting other influential parameters of the gel. 相似文献
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Jie Wei Xiao‐Jie Ju Xiao‐Yi Zou Rui Xie Wei Wang Ying‐Mei Liu Liang‐Yin Chu 《Advanced functional materials》2014,24(22):3312-3323
Novel multi‐stimuli‐responsive microcapsules with adjustable controlled‐release characteristics are prepared by a microfluidic technique. The proposed microcapsules are composed of crosslinked chitosan acting as pH‐responsive capsule membrane, embedded magnetic nanoparticles to realize “site‐specific targeting”, and embedded temperature‐responsive sub‐microspheres serving as “micro‐valves”. By applying an external magnetic field, the prepared smart microcapsules can achieve targeting aggregation at specific sites. Due to acid‐induced swelling of the capsule membranes, the microcapsules exhibit higher release rate at specific acidic sites compared to that at normal sites with physiological pH. More importantly, through controlling the hydrodynamic size of sub‐microsphere “micro‐valves” by regulating the environment temperature, the release rate of drug molecules from the microcapsules can be flexibly adjusted. This kind of multi‐stimuli‐responsive microcapsules with site‐specific targeting and adjustable controlled‐release characteristics provides a new mode for designing “intelligent” controlled‐release systems and is expected to realize more rational drug administration. 相似文献
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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. 相似文献
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Dorina M. Opris Martin Molberg Christian Walder Yee Song Ko Beatrice Fischer Frank A. Nüesch 《Advanced functional materials》2011,21(18):3531-3539
Several polydimethylsiloxane elastomers were developed and investigated regarding their potential use as materials in dielectric elastomer actuators (DEA). A hydroxyl end‐functionalized polydimethylsiloxane was reacted with different crosslinkers and the electromechanical properties of the resulting elastomers were investigated. The silicone showing the best actuation at the lowest electric field was further used as matrix and compounded with encapsulated conductive polyaniline particles. These composites have enhanced properties including increased strain at break, higher dielectric constant as well as, gratifyingly, breakdown fields higher than that of the matrix. One of the newly synthesized composites is compared to the commercially available acrylic foil VHB 4905 (3M) which is currently the most commonly used elastomer for DEA applications. It was found that this material has little hysteresis and can be activated at lower voltages compared to VHB 4905. For example, when the newly synthesized composite was 30% prestrained, a lateral actuation strain of about 12% at 40 V μm?1 was measured while half of this actuation strain at the same voltage was measured for VHB 4905 film that was 300% prestrained. It also survived more than 100 000 cycles at voltages which are close to the breakdown field. Such materials might find applications wherever small forces but large strains at low voltages are required, in, for example, tactile displays. 相似文献
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Kazuhiko Tsurui Masahito Murai Sung‐Yu Ku Craig J. Hawker Maxwell J. Robb 《Advanced functional materials》2014,24(46):7338-7347
Two libraries of random conjugated polymers are presented that incorporate varying ratios of regioisomeric azulene units connected via the 5‐membered or 7‐membered ring in combination with bithiophene or fluorene comonomers. It is demonstrated that the optoelectronic and stimuli‐responsive properties of the materials can be systematically modulated by tuning the relative percentage of each azulene building block in the polymer backbone. Significantly, these materials exhibit stimuli‐responsive behavior in the solid state with spin‐coated thin films undergoing rapid and reversible color switching. Ultimately, this work introduces a new design strategy in which the optoelectronic properties of conjugated polymers can be modulated by varying only the regiochemistry of the constituent building blocks along a polymer chain. 相似文献
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Iryna Gryn Emmanuelle Lacaze Roberto Bartolino Bruno Zappone 《Advanced functional materials》2015,25(1):142-149
Large‐area periodic defect patterns are produced in smectic A liquid crystals confined between rigid plate electrodes that impose conflicting parallel and normal anchoring conditions, inducing the formation of topological defects. Highly oriented stripe patterns are created in samples thinner than 2 μm due to self‐assembly of linear defect domains with period smaller than 4 μm, whereas hexagonal lattices of focal conic domains appear for thicker samples. The pattern type (1d/2d) and period can be controlled at the nematic–smectic phase transition by applying an electric field, which confines the defect domains to a thin surface layer with thickness comparable to the nematic coherence length. The pattern morphology persists in the smectic phase even after varying the field or switching it off. Bistable, non‐equilibrium patterns are stabilized by topological constraints of the smectic phase that hinder the rearrangement of defects in response to field variations. 相似文献
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Guangxi Huang Yuqing Jiang Sifen Yang Bing Shi Li Ben Zhong Tang 《Advanced functional materials》2019,29(16)
Multi‐stimuli‐responsive fluorescent molecule tetraphenylethylene (TPE) derivative 1 is synthesized, which contains a TPE skeleton and peripheries of two methoxyl groups and one carboxyl group. It shows a typical aggregation‐induced emission behavior and also exhibits fluorescence responses to pH change and amine vapors, and multicolored mechanochromic properties. The emission of 1 can be reversibly switched among blue (1p‐f, 462 nm, Φf = 7.4%), bright cyan (1p‐h, 482 nm, Φf = 82.3%), and yellow (1p‐g, 496 nm, Φf = 10.5%) with high contrast through solvent fuming, heating, or grinding. Molecule 1 occurs in four crystalline states (1c‐a, 1c‐b, 1c‐c, and 1c‐d) after crystallization from different solvents. The multicolored mechanochromic property is related to the different interactions and packing modes of molecules in the crystals. The crystals with weak fluorescent emission have characteristic porous structures and corresponding intensive XRD diffraction peaks, which are absent in the crystal with intensive fluorescent emission. The porous structures are critical for the fluorescence intensity of the molecules. Upon heating, the porous structures of crystals are damaged and fluorescence is significantly enhanced. 相似文献
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Kyung Min Lee Matthew L. Smith Hilmar Koerner Nelson Tabiryan Richard A. Vaia Timothy J. Bunning Timothy J. White 《Advanced functional materials》2011,21(15):2913-2918
Cantilevers composed of glassy, photoresponsive liquid crystalline polymer networks (LCNs) are shown to oscillate at high frequency (～50 Hz) and large amplitude when exposed to light from a 442 nm coherent wave (CW) laser. Added dimensionality to previously reported in‐plane oscillations is enabled by adjusting the orientation of the nematic director to the long axis of the cantilever yielding in‐plane bending accompanied by out‐of‐plane twisting (flexural–torsional oscillation). The fundamental photoresponse of this class of glassy azobenzene liquid crystal polymer networks (azo‐LCN) is further probed by examining the influence of cantilever aspect ratio, laser intensity, and temperature. The frequency of photodirected oscillations is strongly correlated to the length of the cantilever while the amplitude and threshold laser intensity for oscillation is strongly correlated to temperature. 相似文献
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Florian Geyer Yuta Asaumi Doris Vollmer Hans‐Jürgen Butt Yoshinobu Nakamura Syuji Fujii 《Advanced functional materials》2019,29(25)
A new type of armored droplet, a so‐called polyhedral liquid marble, is introduced in this work. These armored liquid marbles consist of liquid droplets stabilized by hydrophobic hexagonal plates made of poly(ethylene terephthalate), which adsorb to the liquid–air interface. Depending on the specific combination of plate size and droplet diameter, the plates self‐assemble into highly ordered hexagonally arranged domains. Even tetrahedral‐, pentahedral‐, and cube‐shaped liquid marbles composed of only 4 to 6 plates are demonstrated. During evaporation of the internal liquid, due to the high adsorption energy of the plates at the liquid–air interface, the overall surface area stays constant, resulting in strongly deformed polyhedral liquid marbles. In line with this, highly asymmetric polyhedral liquid marbles and letters are obtained due to the strong interfacial jamming exerted by the rigid hexagonal plates. This is particularly pronounced for larger plate sizes, leading to liquid marbles with unusually sharp edges (for example, rectangular edges). The polyhedral liquid marbles exhibit various stimuli‐responsive behaviors simultaneously being exposed to water, ammonia, or tetrahydrofuran vapors. Air‐driven polyhedral liquid marbles floating on water can reach velocities of several centimeters per second. 相似文献
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We present a novel method to produce bioactive surface patterns whose size can be changed in response to a variation of the environmental conditions, rather than local treatment. Our approach is based on the structured surface‐immobilization of thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) polymer chains with different transition temperatures. We experimentally demonstrate how the size of an area in which a particular polymer is collapsed or swollen can be controlled by ambient temperature. We show the temperature‐induced size‐control of a bioactive surface pattern by embedding functional motor proteins into the switchable polymer layers. 相似文献
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The small‐sized molecules that have been developed from single hydrophobic amino acids (Phe, Trp, Tyr and Leu) by suitably protecting the –NH2 and –CO2H groups generate diverse nanoscopic structures – such as nanorods, nanofibrils, nanotubes, and nanovesicles – depending upon the protection parameters and solvent polarity. The vesicular structures get disrupted in the presence of various salts, such as KCl, CaCl2, (NH4)2SO4 and N(n‐Bu)4Br. Insertion of unnatural (o/m/p)‐aminobenzoic acids as a protecting group and the lack of conventional peptide bonds in the molecules give the nanostructures proteolytic stability. The nanostructures also show significant thermal stability along with a morphological transformation upon heat treatment. Our in vitro studies reveal that the addition of micromolar concentration “curcumin” significantly reduces the formation of amyloid‐like fibrils. These diverse nanostructures are used as a template for fabricating silver nanoparticles on their outer surfaces as well as in the inner part, followed by calcination in air which helps to obtain a 1D silver nanostructure. Furthermore, the nanovesicles are observed to encapsulate a potent drug (curcumin) and other biologically important molecules, which could be released through salt‐triggered disruption of vesicles. 相似文献
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Richard A. Archer Johnathan R. Howse Syuji Fujii Hisato Kawashima Gavin A. Buxton Stephen J. Ebbens 《Advanced functional materials》2020,30(19)
The fabrication of multifunctional polymeric Janus colloids that display catalytically driven propulsion, change their size in response to local variations in pH, and vary cargo release rate is demonstrated. Systematic investigation of the colloidal trajectories reveals that in acidic environments the propulsion velocity reduces dramatically due to colloid swelling. This leads to a chemotaxis‐like accumulation for ensembles of these responsive particles in low‐pH regions. In synergy with this chemically defined accumulation, the colloids also show an enhancement in the release rate of an encapsulated cargo molecule. Together, these effects result in a strategy to harness catalytic propulsion for combined autonomous transport and cargo release directed by a chemical stimulus, displaying a greater than 30 times local cargo‐accumulation enhancement. Lactic acid can be used as the stimulus for this behavior, an acid produced by some tumors, suggesting possible eventual utility as a drug‐delivery method. Applications for microfluidic transport are also discussed. 相似文献
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Indong Jun Seok Joo Kim Ji‐Hye Lee Young Jun Lee Young Min Shin Eunpyo Choi Kyung Min Park Jungyul Park Ki Dong Park Heungsoo Shin 《Advanced functional materials》2012,22(19):4060-4069
The structure of tissue plays a critical role in its function and therefore a great deal of attention has been focused on engineering native tissue‐like constructs for tissue engineering applications. Transfer printing of cell layers is a new technology that allows controlled transfer of cell layers cultured on smart substrates with defined shape and size onto tissue‐specific defect sites. Here, the temperature‐responsive swelling‐deswelling of the hydrogels with groove patterns and their versatile and simple use as a template to harvest cell layers with anisotropic extracellular matrix assembly is reported. The hydrogels with a cell‐interactive peptide and anisotropic groove patterns are obtained via enzymatic polymerization. The results show that the cell layer with patterns can be easily transferred to new substrates by lowering the temperature. In addition, multiple cell layers are stacked on the new substrate in a hierarchical manner and the cell layer is easily transplanted onto a subcutaneous region. These results indicate that the evaluated hydrogel can be used as a novel substrate for transfer printing of artificial tissue constructs with controlled structural integrity, which may hold potential to engineer tissue that can closely mimic native tissue architecture. 相似文献
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Eric Głowacki Karen Horovitz Ching W. Tang Kenneth L. Marshall 《Advanced functional materials》2010,20(17):2778-2785
We have fabricated switchable gas permeation membranes in which a photoswitchable low‐molecular‐weight liquid crystalline (LC) material acts as the active element. Liquid crystal mixtures are doped with mesogenic azo dyes and infused into commercially available track‐etched membranes with regular cylindrical pores (0.40 to 10.0 μm). Tunability of mass transfer can be achieved through a combination of (1) LC/mesogenic dye composition, (2) surface‐induced alignment, and (3) reversible photoinduced LC‐isotropic transitions. Photo‐induced isothermal phase changes in the imbibed material afford large and fully reversible changes in the permeability of the membrane to nitrogen. Both the LC and photogenerated isotropic states demonstrate a linear permeability/pressure relationship, but they show significant differences in their permeability coefficients. Liquid crystal compositions can be chosen such that the LC phase is more permeable than the isotropic—or vice versa – and can be further tuned by surface alignment. Permeability switching response times are 5 s, with alternating UV and >420‐nm radiation at an intensity of 2 mW/cm2 being sufficient for complete and reversible switching. Thermal and kinetic properties of the confined LC materials are evaluated and correlated with the observed permeation properties. We demonstrate for the first time reversible permeation control of a membrane with light irradiation. 相似文献