Wrinkle Structures Research Articles

Tuning the Wrinkles in 3D Graphene Architectures for Mass and Electron Transport

AbstractDue to the high in‐plane Young's modulus and defects, graphene is prone to deformations such as wrinkles. The effects of wrinkles on the mass and electron transport properties need to be elucidated as graphene has great potential in applications such as catalysis, sensors, energy storage, and conversion. In this paper, the wrinkling of graphene oxide sheets is dominated by the mass ratio of graphene oxide to N,N′‐dicyclohexylcarbodiimide (DCC) to fabricate 3D graphene architectures (TDGAs) with tunable porosity. This template‐free DCC tactic of regulating the wrinkling procedure forms hierarchical porosity and modulates the exposure of defect sites. Considering the confinement effect of the wrinkles and defect sites, orthorhombic phase Nb2O5 (T‐Nb2O5) nanoparticles are loaded onto TDGAs, and as‐obtained T‐Nb2O5@TDGAs composites exhibit favorable properties of Li‐ion and electron transport after the wrinkle structures are optimized. The DCC tactic manifests excellent performance in manipulating mass transport properties through tuning the wrinkles on TDGAs‐based composites, which may greatly contribute to graphene based materials with high performances in energy storage.

Regulating surface wrinkles using light.

Regulating existing micro and nano wrinkle structures into desired configurations is urgently necessary yet remains challenging, especially modulating wrinkle direction and location on demand. In this work, we propose a novel light-controlled strategy for surface wrinkles, which can dynamically and precisely regulate all basic characteristics of wrinkles, including wavelength, amplitude, direction and location (λ, A, θ and Lc), and arbitrarily tune wrinkle topographies in two dimensions (2D). By considering the bidirectional Poisson's effect and soft boundary conditions, a modified theoretical model depicting the relation between stress distributions and the basic characteristics was developed to reveal the mechanical mechanism of the regulation strategy. Furthermore, the resulting 2D ordered wrinkles can be used as a dynamic optical grating and a smart template to reversibly regulate the morphology of various functional materials. This study will pave the way for wrinkle regulation and guide fabrication technology for functional wrinkled surfaces.

Formation of the Wrinkle Structure on a Styrene–Butadiene–Styrene Block Copolymer Surface by Surface Chemical Reformation via Ion-Beam Irradiation

A styrene-butadiene-styrene (SBS) block copolymer was utilized to fabricate the wrinkle pattern in accordance with the buckling theory, and ion-beam (IB) irradiation was applied to induce surface r...

Formation of Wrinkle Structures on Styrene-b-isoprene-b-styrene Films Using One-Step Ion-Beam Irradiation

We investigated the wrinkle formation on ion-beam (IB)-irradiated substrates coated with the thermoplastic elastomer styrene-b-isoprene-b-styrene (SIS) and demonstrate a relation of the wrinkle structure and the newly formed top layer induced by IB. IB irradiation led to polymer crosslinking on the surface, thereby forming a new skin layer, a finding which was supported by an X-ray photoelectron spectroscopy analysis, Young's moduli calculated using force-distance curves, and time-of-flight secondary ion mass spectrometry depth profiling. The wrinkle wavelength increased according to the irradiation time, which indicates that the latter mainly increased the thickness of the crosslinking layer. The increase in the wrinkle wavelength varied from 420 to 670 nm by changing the IB irradiation time. In this paper, we present not only the expectation of wrinkle fabrication using our method, but also the possibility of choosing diverse materials such as the thermoplastic elastomer SIS for fabrication of wrinkle structures.

Flexible and stretchable MXene/Polyurethane fabrics with delicate wrinkle structure design for effective electromagnetic interference shielding at a dynamic stretching process

Abstract Flexible materials with favorable electromagnetic wave interference (EMI) shielding performance are highly desirable to response to the fast-growing wireless technologies and flexible electronic devices. However, next-generation of wireless techniques or electronic devices should withstand multiple deformation forms such as bending, folding, wrinkling and stretching. Among them, it is rather difficult for shielding materials to achieve high performance at a dynamic stretching process due to the gradually dropdown of electrical conductivities when increasing tensile deformation. Herein, for the first time, we report a highly flexible and stretchable electrospun polyurethane (PU) nanofibers fabric covered by MXene (Ti3C2Tx) with delicate wrinkle structure design to meet this demand. The as-prepared MXene/PU fabric with sandwich structure exhibits stable mechanical properties and can keep EMI shielding values (SE) (>~20 dB) at a stretching process within 30% deformation. These amazing properties of the composite fabrics make them promising candidates for EMI shielding applications in wireless technologies, robots joints and flexible electronic devices.

Wrinkled smart surfaces: Enhanced switchable wettability and directional liquid transportation

Smart surfaces that can convert external stimuli to changes of surface properties are playing a significant role in both fundamental research and practical applications. However, it is still a challenge to create smart surfaces with good switchability in a facile and controllable way. Herein, a wrinkled smart surface is prepared by a strategy which combines stimuli-responsive polymers and surface wrinkles, where polymers provide surface responsiveness and wrinkles result in enhancement and a regulation effect. A model system composed of the pH-responsive polymer PDEAEMA grafted on the surface of a wrinkled Au/PS bilayer via Au-SH bonding is presented. The contact angle (CA) difference between acidic/basic droplets is found to be much larger for wrinkled surfaces (~117°) than that of flat surfaces (~30°), suggesting that wrinkles can significantly reinforce the switchability of wetting. Moreover, by taking advantage of wrinkles in sample processing and high controllability, we further optimize the wrinkle structure and incorporate asymmetric patterns into the wrinkled smart surface, thereby achieving directional manipulation of acidic and basic droplets/liquids. Due to the excellent capability found in this study, wrinkled smart surfaces may find potential applications in sensors, microfluidics, separation, and smart interfacial design.

Stretchable and durable Parylene/PEDOT:PSS/Parylene multi-layer induced by plastic deformation for stretchable device using functionalized PDMS

Currently, electronic components having wavy structures are being actively studied because such wavy structures exhibit stretchability through flattening under stretching. The buckling of a thin film on an elastomer is an easy and inexpensive approach of creating a wavy structure and has attracted considerable attention. Despite its simplicity and easiness, the requirement of stretchers during film deposition limits fabrication methods, such as spin-coating and printing methods, and hinders their application in industry. Here, we eliminated the requirement of stretchers during film deposition by utilizing plastic deformation of the thin film and extending methods of developing a wrinkle structure. We used poly-3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), the most widely used conductive polymer, as a thin film and adopted its stretchable wrinkle structure for stretchable electronic devices. The stretchability and durability of PEDOT:PSS were enhanced by sandwiching the PEDOT:PSS layer between two Parylene layers. The PEDOT:PSS layer was conductive at a stretch of up to 170%, and the change in resistance was less than 10% after 4000 cyclic loads. Additionally, we demonstrated a new concept of a flexible and stretchable light emitting device using the proposed Parylene/PEDOT:PSS/Parylene multi-layer and functionalized polydimethylsiloxane.

Geometry Control of Wrinkle Structures Aligned on Hydrogel Surfaces.

Surface geometries in nature such as wrinkle structures have various functions. Attention has been paid to the fabrication method of the geometry and geometry control by external stimuli. This is because surface geometries as an active interface are able to contribute to the control of interactions with the external environment. In this study, aligned wrinkles were fabricated on the surface of stretched hydrogels in aqueous conditions by the electrophoretic formation of a polyion complex layer. The geometry of wrinkles was controlled by the stretching ratio and Young's modulus of hydrogels, and hierarchical wrinkle structures were fabricated after unloading the stretched hydrogels. Therefore, it can be a new wrinkle-formation method capable of transferring the initial elastic anisotropy of the substrate material to the wrinkle structure. Creation of thermoresponsive wrinkles that can transform their geometrical configuration reversibly was achieved by fabrication of aligned wrinkles on the surface of thermoresponsive hydrogels.

Wrinkle structure on multifunctional MOFs to facilitate PPCPs adsorption in wastewater

A novel multifunctional metal-organic frameworks (MOFs) UiO-66@Fe3O4@UiO-66 (UiO = University of Oslo) was fabricated to adsorb pharmaceuticals and personal care products (PPCPs) under near neutral conditions. We designed a wrinkle structure on the surface of UiO-66@Fe3O4@UiO-66 by seeded growth strategy. These wrinkles were composed of Fe3O4 nanoparticles and outermost UiO-66. It made the specific surface area of the MOFs increases, and provided multiple active sites for a representative pollutant salicylic acid (SA) adsorption. Moreover, lattice defects formed during secondary growth facilitating the coordination interaction between SA and the secondary building unit of UiO-66@Fe3O4@UiO-66 under near neutral conditions. These advantages made the adsorption capacity of per unit mass UiO-66 in UiO-66@Fe3O4@UiO-66 about 42% higher than that of the pristine UiO-66, and the removal rate of 1 mg L−1 SA reach 64.5% in real wastewater. Furthermore, magnetic Fe3O4 particles in the wrinkles exhibited outstanding magnetic separation performance. So that UiO-66@Fe3O4@UiO-66 can be effectively separated from the liquid media and regenerated after adsorption. The results show that the wrinkled MOFs could be used as an excellent candidate for SA adsorption in real wastewater. More importantly, this strategy could guide the preparation of different kind of MOFs to adsorb PPCPs in wastewater.

Inspiration of wrinkles in layered material for the mechanism study of several geological activities

In this work, we propose a universal method of preparing wrinkle structures in layered crystals, which provides a good model for studying the physical properties of layered materials under strain. More importantly, there are some similarities between wrinkle engineering and geological activities, which inspires us to give some possible explanations to the mechanism for geological activities like earthquake and volcanic. The wrinkle structures of layered crystals can be achieved by exerting uniaxial or biaxial stress on the flexible substrate, which is very similar to the layered structure of the Earth and the formation of mountain folds on the Earth's surface. Since the Earth has an uneven mass distribution and self-rotation as well, the moments of inertia for plates are different from each other. Here in this work, we point out that there is a difference in angular velocity between the north hemisphere and south hemisphere, which may strongly influence the topography and geology activities near the equator. This work provides a possible mechanism explanation for several geological phenomena such as earthquakes, volcanoes, and continental drift. Based on China's special topography, we propose a matter flow hypothesis and discuss the orientation of matter flow in detail. We point out that the geological activity mechanism in China and the regions around plate boundaries is quite different. The matter flow hypothesis can be well applied to explain the causes of earthquake disasters in China, the distribution of mineral resources, and the possible causes of oil in the Middle East countries. Besides, it also provides a new theoretical guidance for predicting the earthquake disasters and prospecting the mineral resources in China. This work provides a new idea for humans to avoid natural disasters, to understand the natural phenomena on the Earth, and to make rational use of natural resources.

Trace fossils from the Mississippian of the Piaskowa Góra section (the Intra-Sudetic Basin, SW Poland)

Eight ichnotaxa and enigmatic tubular forms were discovered and described for the first time from clastic deposits (the Culm facies) of the uppermost part of the Szczawno Formation (upper Mississippian) from in the Piaskowa Góra section in the northern part of the Intra-Sudetic Basin near Wałbrzych. The trace fossils are represented mostly by pascichnia and less numerous domichnia, fodinichnia and repichnia. Psammichnites plummeri and numerous Phycosiphon isp . are the most common ichnotaxa. They are accompanied by Archaeonassa fossulata, Beaconites cf. capronus , Curvolithus multiplex, Dictyodora liebeana, Palaeophycus isp ., and Planolites isp . D. liebeana is described for the first time from the lower Serpukhovian. Most components of the ichnoassemblage are typical of the Cruziana ichnofacies, but the co-occurrence of Dictyodora and Phycosiphon could indicate a transition to deeper environmental settings (the Zoophycos ichnofacies). The lithological features as well as the accompanying trace fossils, wrinkle structures and floral remains of Archaeocalamites indicate rapid sedimentation, alternating with more tranquil periods of sedimentation, in an intermediate environment between the lower offshore (the distal Cruziana ichnofacies) and the fan-delta slope (below the wave base, the Zoophycos ichnofacies). The studied trace fossils and palynological data indicate that marine conditions in the Wałbrzych area in the Mississippian prevailed locally until the early Sepukhovian.

A multidimensional hierarchical structure designed for lateral strain-isolated ultrasensitive pressure sensing

A brand new multidimensional hierarchical structure (a wrinkle structure in the pre-stretching direction and arch structure in the perpendicular direction) is designed and introduced in strain-isolated ultrasensitive piezoresistive sensing.

Fibrous silica HZSM-5 towards CO2 adsorption performance: Effect of copper oxide loading

CO2 adsorption is one of the technologies to reduce CO2 from gas mixture in atmosphere which contributes to global warming through greenhouse effect. Hence, many studies have been conducted to explore the most effective techniques for reducing the amount of carbon dioxide in the atmosphere. In this study, effect of different weight percent CuO (5–20 wt%) loaded onto fibrous silica HZSM-5 (FHZSM-5) towards CO2 adsorption performance was investigated. Firstly, fibrous silica HZSM-5 (FHZSM-5) was synthesized via combining microemulsion-seed crystallization technique and followed by CuO loading using wet impregnation method. Furthermore, characterizations were performed by using XRD, FTIR, N2 physisorption and FESEM in order to confirm the structure and morphology of the material. Lastly, the CO2 physisorption capability of the material is examined. The XRD and N2 physisorption results showed the presence of CuO peaks, reduced crystallinity and decreased the surface area of FHZSM-5 with the increasing loading of CuO. The FTIR analysis proved the interaction of CuO with the FHZSM-5 framework. The FESEM analysis demonstrated the presence of wrinkle structure on FHZSM-5. The CO2 adsorption performance was in sequence of FHZSM-5 (36.8 cm3/g) > 5CuO/FHZSM-5 (26.1 cm3/g) > 10CuO/FHZSM-5 (20.5 cm3/g) > 20CuO/FHZSM-5 (18.9 cm3/g) > 5CuO/SiO2 (4.5 cm3/g). Current study revealed the potential of fibrous morphology, importance of high surface area and porosity in FHZSM-5 for enhancing CO2 physical adsorption performance.

Analysis of hierarchical wrinkle structure generated in thin film on winkler spring substrate

The buckling deformation of a structure consisting of a soft substrate and a hard thin film induces autonomous formation of a fine periodic structure represented by wrinkles. In recent years, a hierarchical wrinkle structure in which wrinkles with different periods are superimposed has attracted attention, and its engineering application is expected. However, no methodology has been established for structural control. In this study, we investigate the mechanism of autonomous formation of hierarchical wrinkle structure using thin film-winkle spring substrate system.

Facile synthesis of tunable dendritic fibrous SBA-15 (DFSBA-15) with radial wrinkle structure

Abstract In this study, typical mesoporous hexagonal rod-typed SBA-15 was successfully transformed into spherical shape with additional dendrimers, namely Dendritic Fibrous SBA-15 (DFSBA-15) by employing microwave-assisted microemulsion system. Physiochemical properties of DFSBA-15 were greatly influenced by aging temperature, urea/TEOS ratio, co-surfactant types, and aging time. It was found that the co-surfactant types were insignificant in controlling the pore size, while the aging conditions (temperature and time) were significant in controlling the fiber density. The analysis results (XRD, N2 physisorption, FTIR, and TEM) confirmed the optimal conditions for DFSBA-15 synthesis were at aging temperature of 100 °C, urea/TEOS ratio of 0.5, n-butanol as co-surfactant, and aging time of 12 h. The as-synthesized optimized DFSBA-15 was compared with the conventional SBA-15 via XRD, N2 physisorption, FTIR, CO2-TPD, NH3-TPD, TGA, TEM, and FESEM-EDX. As compared, DFSBA-15 rendered vast accessibility to the adsorption sites, higher basicity ( ≈ 86% enhancement) and acidity ( ≈ 66% enhancement), abundant siliceous framework and higher thermal stability ( ≈ 19% enhancement), owing to its radially oriented pores which elongated to the outer surface from the nucleus of its sphere. The outcome of this study anticipated the wide applications of DFSBA-15 in catalysis and biomedical fields by revealing the facile protocols of optimal DFSBA-15 synthesis.

Hydrogel Adhesion by Wrinkling Films.

A novel adhesion control method for hydrogels utilizing swelling-induced wrinkling gel films is developed. Structures such as flat, crease, and wrinkle at the interface of adhered gels are controlled by swelling ratio of gel films. The role of microstructures at the gel-gel interface is investigated by adhesive strength measurement. Aligned wrinkles are fabricated with anisotropic swelling films. The adhesive strength of hydrogels with wrinkles parallel to tensile direction is larger than that with perpendicular wrinkles. Adhered gels detach without damage to their surfaces when the wrinkle structures are disrupted by peeling of the wrinkled film. Moreover, thermoresponsive film is used to control wrinkle structures at the adhered interface by temperature. The adhered interface is stable in cold water because of the existence of wrinkles; however, they detach in hot water due to wrinkle deformation. By using wrinkle structure at adhesive interfaces, both strong adhesion and easy detachment of hydrogels are achieved.

Capacitive Force Sensor with Wide Dynamic Range Using Wrinkled Micro Structures as Dielectric Layer.

We propose a wide dynamic range capacitive force sensor with two wrinkle-structured elastomer layers as a dielectric layer. The sensor consists of electrodes on each substrate and two dielectric layers between them. The electrode is made of platinum and fabricated by using a lift-off process. The polyimide film is used as a substrate. Two wrinkle-structured dielectric layers, which are placed in perpendicular direction, are made by poly(dimethylsiloxane) (PDMS) replica molding process. With the pressure applied on the device, dielectric layers deform while decreasing distance between the electrodes and thus increasing the capacitance of the sensor. The orthogonally positioned wrinkled structures make possible to increase the dynamic range of the capacitive cell. The proposed capacitive sensor operates in the pressure range of 1 MPa with the maximum sensitivity of 0.06%/kPa.

Skin-Inspired Humidity and Pressure Sensor with a Wrinkle-on-Sponge Structure.

Sensors with multifunctions have attracted great attention for their extensive application value, among which humidity sensing and pressure sensing are necessary to electronics undoubtedly because of the complex physical environment we live in. Inspired by the structure of skin, in this article, we design a new method to combine wrinkle structure with porous sponge structure and achieve a novel, flexible, compressible, and bifunctional sensor based on carbon nanotube-polydimethylsiloxane (CNT-PDMS) with functions of humidity sensing and pressure sensing. The performance of the humidity sensing part can be controlled by the ultraviolet and ozone (UVO) treatment time and CNT concentration, while the sensitivity of the pressure sensing part can be controlled by the CNT concentration and grinding time of sugar granules. The bifunctional sensor can easily sense approaching and touching of a hand, which shows great potential of alarming and protecting some electronics. Moreover, the bifunctional sensor can also be used in detecting human joint motions and breath conditions as a wearable and flexible health monitor.

Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada

Abstract Microbially induced sedimentary structures (MISS) are reportedly widespread in the Early Triassic and their occurrence is attributed to either the extinction of marine grazers (allowing mat preservation) during the Permo-Triassic mass extinction or the suppression of grazing due to harsh, oxygen-poor conditions in its aftermath. Here we report on the abundant occurrence of MISS in the Lower Triassic Blind Fiord Formation of the Sverdrup Basin, Arctic Canada. Sedimentological analysis shows that mid-shelf settings were dominated by deposition from cohesive sand-mud flows that produced heterolithic, rippled sandstone facies that pass down dip into laminated siltstones and ultimately basinal mudrocks. The absence of storm beds and any other “event beds” points to an unusual climatic regime of humid, quiet conditions characterized by near continuous run off. Geochemical proxies for oxygenation (Mo/Al, Th/U, and pyrite framboid analysis) indicate that lower dysoxic conditions prevailed in the basin for much of the Early Triassic. The resultant lack of bioturbation allowed the development and preservation of MISS, including wrinkle structures and bubble textures. The microbial mats responsible for these structures are envisaged to have thrived, on sandy substrates, within the photic zone, in oxygen-poor conditions. The dysoxic history was punctuated by better-oxygenated phases, which coincide with the loss of MISS. Thus, Permo-Triassic boundary and Griesbachian mudrocks from the deepest-water settings have common benthos and a well-developed, tiered burrow profile dominated by Phycosiphon. The presence of the intense burrowing in the earliest Triassic contradicts the notion that bioturbation was severely suppressed at this time due to extinction losses at the end of the Permian. The notion that Early Triassic MISS preservation was caused by the extinction of mat grazers is not tenable.

Spontaneously formed organic wrinkle structure for top-emitting organic light emitting diodes

Due to the imperfections of top metal electrodes, top-emitting organic light emitting diodes (TEOLEDs) suffer low efficiencies and non-uniform angular emission spectral characteristics. We demonstrate a novel and simple method of overcoming these drawbacks by directly forming wrinkles on the thin film encapsulation (TFE) surface of TEOLEDs. The developed method relies on the use of a liquid prepolymer that spontaneously forms randomly distributed micron-sized wrinkles upon exposure to ultra-violet light. The wrinkles contribute to the extraction of light confined in the air mode by widening the angle of the escape cone, leading to a 1.4-fold increase in the current efficiency. Due to the spatial randomness of the organic wrinkle structure, almost negligible spectral angular dependency was achieved. As a merit of the simple process at room temperature without complicated processes such as patterning and vacuum processes, the developed organic wrinkle structure can be directly used to enhance the characteristics of TEOLEDs, and is expandable to flexible OLEDs and various optoelectronic devices.