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Switchable adhesion, especially that responds to both solids and liquids simultaneously, has recently attracted much attention due to its wide applications. However, it is hard to endow a surface with switchable solid/liquid adhesion and high maximum solid adhesion at the same time due to the opposing requirement of solid contact fraction. In this paper, a shape memory/elasticity dual‐structure adjustable strategy to satisfy that special demand is offered. In detail, by constructing the shape memory epoxy resin arrays with spherical polyurethane mushroom on Fe3O4 doped substrate, a smart photo/thermal responsive material with switchable solid/liquid adhesion is prepared. In the work, the structure of the shape memory resin arrays can be reversibly changed between upright and collapsed states, leading to switchable solid and liquid adhesion. Meantime, the structure of the polyurethane mushroom can be squeezed to increase the contact area with the solid and spontaneously recovered, which can effectively improve the maximum solid adhesion with no effect on liquid adhesion. Furthermore, the obtained material has good cyclicity and universality, which has been applied to selectively pick silicon wafers and water droplets. The findings of this study may provide new strategies for the development of smart adhesive materials. [ABSTRACT FROM AUTHOR]

Recently, slippery surfaces with controllable droplet sliding have aroused much attention in both fundamental research and realistic applications. However, for almost all existing surfaces, constant stimuli such as heat, light, magnetic field, etc., are indispensable. Herein, by constructing pit structures on a shape memory polymer and further infusing oil with low surface tension, we report a shape memory slippery surface that can overcome the above imperfection. Based on the shape memory performance, the surface can memorize a diverse pit size as the surface is stretched or recovered. With the variation of pit structure, the sliding performances for both water and organic liquid droplets can be reversibly adjusted between the rolling and pinning states. This work, based on the shape memory effect, reports smart droplet sliding control through regulating the surface microstructure, which not only provides a strategy for droplet sliding control, but also offers some ideas for designing novel intelligent slippery surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • The membrane can regulate the adhesion to both solid and water droplets. • Both microstructure and surface energy were crucial for special adhesion. • The membrane can be used to in-situ capture/release both solid and liquid. Recently, inspired by gecko's smart adhesion, many intelligent adhesive surfaces have been reported. However, all of these are focused on single adhesion to liquid or solid, to obtain a surface with switchable adhesion to both water and solid is still a challenge. Herein, by coating a layer of polyurethane (PU) with micropillar structures onto a shape memory polymer (SMP) substrate to imitate the skin and muscle of the gecko's foot, respectively, we report a new shape memory film that can repeatedly display curved/unfolded shapes with the help of the excellent shape memory property. Research results indicate that besides the variation of the contact area, a proper surface energy is also crucial for the special adhesion. Furthermore, based on the smart adhesive performance, in-situ capture/release of both solid and liquid were demonstrated by using the film. This research proposes a film with tunable adhesion to both solid and liquid, which provides a fresh idea for designing novel adhesive film, and meanwhile broadens the application of the adhesive materials. [ABSTRACT FROM AUTHOR]

A novel patterned superhydrophobic surfaces with shape memory performance is reported. Based on the shape memory ability in surface microstructure, the surface pattern and corresponding wettability can be reversibly controlled between various states, such as high/low adhesions and isotropic/anisotropic wettings. And the patterned surface has special advantages compared with traditional hydrophilic patterns such as anti-pollution property and excellent stability were also demonstrated. • New patterned superhydrophobic surfaces with shape memory performance are designed. • The pattern and corresponding wettability can be reversibly controlled. • The patterned surface has anti-pollution property and excellent stability. • The surface can be used in droplet storage, capture and directional transportation. Recently, more and more attention has been focused on superhydrophobic patterned surfaces with controllable wettability and adhesion. However, almost all present works are based on designing hydrophilic patterns onto the superhydrophobic surfaces. Smart wetting control on microstructure patterned surfaces is still extremely rare since reversible regulating surface microstructure is relatively more difficult. Herein, we report such a strategy for smart surface wetting control. As a demonstration, a superhydrophobic shape memory polymer (SMP) array was prepared, patterns such as dots and lines can be easily obtained through pressing structured templates on the surface, and such patterns can be removed after a further heating process. During the whole process, lots of surface wetting properties including large/small contact angles, high/low adhesions, and isotropic/anisotropic sliding abilities can be reversibly controlled. The smart controllability comes from the excellent shape memory effect (SME) of the material, which can memorize and present diverse microstructure patterns and solid/liquid contact models. Furthermore, some applications including droplet storage, capture/release, directional transportation, and special advantages compared with traditional hydrophilic patterns such as anti-pollution property and excellent stability were also demonstrated. This work not only opens a novel way for controlling surface wetting, but also provides a new superhydrophobic platform for manipulation of microdroplet. [ABSTRACT FROM AUTHOR]

• A new surface is prepared by coating the TiO 2 nanoparticles on the SMP pillar arrays. • The surface realize the restoration of superhydrophobic/superhydrophilic switching. • The restorable functional application in droplet storage is demonstrated. • The strategy can easily be extended to other inorganic oxides, such as ZnO and V 2 O 5. Recently, the switchable wetting surfaces between superhydrophobicity and superhydrophilicity have been widely studied. However, for almost all existing surfaces, especially inorganic responsive smart surfaces (TiO 2 , ZnO, etc.), their surface microstructures are easily damaged under external force, thus resulting in the loss of superwetting switching and corresponding functions. Realizing the restoration of the damaged surface microstructures would be promising to solve the problem, but it has never been reported. Herein, we advance a fresh strategy to solve the above question by combining shape memory polymer (SMP) and TiO 2 nanoparticles. The as-prepared TiO 2 coated SMP arrays have an excellent responsivity between superhydrophobicity and superhydrophilicity under alternation of UV irradiation and storage in dark. After pressing, the collapsed arrays can only achieve the limited wetting switching between hydrophobicity and hydrophilicity under the same treating condition. Importantly, SMP can help the collapsed surface microstructure recover the initial morphology based on its shape memory effect, and realizing the restoration of superwetting switching. The restorability is ascribed to the cooperative effect between the shape memory property of the SMP and UV-induced surface chemistry variation of TiO 2 nanoparticles. Furthermore, the restorable functional application in droplet storage is also demonstrated. This work provides a fresh idea for designing new smart superwetting surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • A beetle-inspired surface is prepared by loading silicone oil into the SMP arrays. • The surface can show switchable adhesion to both solid and liquid simultaneously. • The switchable adhesion enables in-situ gripping / release of solids. • Directed liquid shedding is achieved on a surface with contrary adhesion behaviors. Surfaces with switchable adhesion have been vigorously investigated over the past decades by mimicking the unique adhesive mechanisms of living systems. However, designing a universal intelligent adhesive surface for both solid and liquid remains a challenge. Herein, drawing inspiration from the controllable capillary forces generated by muscle movements and oil-secretion on the foot pads of the beetle (Hemisphaerota cyanea), we report a novel oil-loaded shape memory polymer (SMP) micropillars with such smart controllability. Based on the shape memory effect (SME) of the SMP, the pillars can be reversibly switched between the tilted state and the upright state, which simultaneously changes the distribution of the trapped oil, and thus generates different capillary forces. This variation results in reversible adhesion behaviors of the surface to diverse solids including flat glass, CD disk, polytetrafluoroethylene (PTFE), rough glass, sandpaper, nylon net, and liquid droplets like acid, basic, salt-containing water droplets, and some organic liquids such as glycol, glycerol, and formamide. Given its smart adhesion, the surface was further applied in in-situ gripping/release of solid objects and directed liquid shedding. This work provides a new design strategy for smart adhesive materials, which may contribute to the development of smart grippers, microfluidics, etc. [ABSTRACT FROM AUTHOR]