Hierarchical micropapillae and nanofolds are known to exist on the petals' surfaces of red roses. These micro-and nanostructures provide a sufficient roughness for superhydrophobicity and yet at the same time a high adhesive force with water. A water droplet on the surface of the petal appears spherical in shape, which cannot roll off even when the petal is turned upside down. We define this phenomenon as the "petal effect" as compared with the popular "lotus effect". Artificial fabrication of biomimic polymer films, with well-defined nanoembossed structures obtained by duplicating the petal's surface, indicates that the superhydrophobic surface and the adhesive petal are in Cassie impregnating wetting state.

A low-cost, high-oil-adsorption film consisting of polystyrene (PS) fibers is fabricated by a facile electrospinning method. Different fiber diameter and porous fiber's surface morphology play roles in oil adsorption capacity and oil/water selectivity. The results showed that oil adsorption capacity of PS oil sorbent film with small diameter and porous surface structure for diesel oil, silicon oil, peanut oil and motor oil were approximate to 7.13, 81.40, 112.30, and 131.63 g/g, respectively. It was higher than normal fibrous sorbent without any porous structure. The thinner porous PS oil sorbent also had excellent oil/water selectivity in the cleanup of oil from water.

An interesting ''water diode'' film is fabricated by a facile electrospinning technique. The fibrous film is a composite of hydrophobic polyurethane (PU) and hydrophilic crosslinked poly (vinyl alcohol) (c-PVA) fibrous layers. By taking advantages of the hydrophobichydrophilic wettability difference, water can penetrate from the hydrophobic side, but be blocked on the hydrophilic side.Heterogeneous materials are attractive because they may endow new functions different to the intrinsic properties of two original materials, which plays vital important roles in physics, chemistry and electronics domains. 1 The most representative case among heterogeneous materials is the diode, which allows unidirectional electric conduction by a couple of p-type and n-type semiconductors. In this communication, we reported an interesting ''water diode'' film, by which water can spontaneously penetrate from one side to another side, while blocking penetration in the reverse direction.Functional surfaces with special wettability are of both fundamental and technological significance. Fruitful achievements have demonstrated that chemical composition as well as surface topology evidently affect the surface wettability. 2-7 Recently, researchers found that rice leaf and butterfly wings consist of oriented surface micro/ nanostructures, which afford an intriguing planar anisotropic wettability. On these surfaces, water drops can easily roll in the parallel direction of the orientation instead of in the perpendicular direction. 8,9 These findings immediately inspired wide interest in the investigation of surfaces with anisotropic wettability. Various elegant chemical or physical methods have been proposed in manufacturing anisotropic wetting surfaces by modifying the surface with gradient free energy chemicals 10-12 or building asymmetric topologies such as grooves, 13,14 channels, 15,16 or slanted pillars on surfaces. 17,18 However, most of the current studies are still concentrated on the two-dimensional plane, harnessing wetting performance in three-dimensions is seldom achieved 19 and its underlying mechanism is still undeveloped. Herein, we designed and fabricated a composite film with heterogeneous wettability by seamless coupling a fibrous hydrophobic polyurethane (PU) film and a hydrophilic crosslinked poly (vinyl alcohol) (c-PVA) film. By taking advantages of the distinct hydrophobic-hydrophilic difference, an interesting unidirectional water-penetration function has been successfully realized. Water can spontaneously penetrate from the hydrophobic side to the hydrophilic side of the film, but this is not the case for the reverse direction. Differences in the surface energy between these two materials as well as microporous structures arise from fibrous structures, resulting in the novel unidirectional water penetration phenomenon. Such composite films which demonstrate water penetration in one direction may provide many fascinating applications such as smart texture and flowing control devices.The composite PU/c-PVA fibrous fil...

A multifluidic coaxial electrospinning approach is reported here to fabricate core/shell ultrathin fibers with a novel nanowire-in-microtube structure from more optional fluid pairs than routine coaxial electrospinning. The advantage of this approach lies in the fact that it introduces an extra middle fluid between the core and shell fluids of traditional coaxial electrospinning, which can work as an effective spacer to decrease the interaction of the other two fluids. Under the protection of a proper middle fluid, more fluid pairs, even mutually miscible fluids, can be operated to generate "sandwich"-structured ultrathin fibers with a sharp boundary between the core and shell materials. It thereby largely extends the scope of optional materials. Selectively removing the middle layer of the as-prepared fibers results in an interesting nanowire-in-microtube structure. Either homogeneous or heterogeneous fibers with well-tailored sandwich structures have been successfully fabricated. This method is an important extension of traditional co-electrospinning that affords a more universal avenue to preparing core/shell fibers; moreover, the special hollow cavity structure may introduce some extra properties into the conventional core/shell structure, which may find potential applications such as optical applications, microelectronics, and others.

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Wearable and stretchable electronics including various conductors and sensors are featured with their lightweight, high flexibility, and easy integration into functional devices or textiles. However, most flexible electronic materials are still unsatisfactory due to their poor recoverability under large strain. Herein, we fabricated a carbon nanotubes (CNTs) and polyurethane (PU) nanofibers composite helical yarn with electrical conductivity, ultrastretchability, and high stretch sensitivity. The synergy of elastic PU molecules and springlike microgeometry enable the helical yarn excellent stretchability, while CNTs are stably winding-locked into the yarn through a simple twisting strategy, making good conductivity. By virtue of the interlaced conductive network of CNTs in microlevel and the helical structure in macrolevel, the CNTs/PU helical yarn achieves good recoverability within 900% and maximum tensile elongation up to 1700%. With these features, it can be used as a superelastic and highly stable conductive wire. Moreover, it also can monitor the human motion as a rapid-response strain sensor by adjusting the content of the CNTs simply. This general and low-cost strategy is of great promise for ultrastretchable wearable electronics and multifunctional devices.

Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.