The aquatic fern salvinia can retain an air layer on its hairy leaf surface when submerged under water, which is an inspiration for biomimetic applications like drag reduction. In this research, an electrostatic flocking technique is used to produce a hairy surface to mimic the air-trapping performance of the salvinia leaf.Viscose and nylon flocks with different sizes were selected. A volumetric method was established to analyze the air-retaining performance of the flocking samples, Salvinia molesta and lotus leaves as well.Through air volume change analyses, it is found that another factor that can affect the Salvinia molesta air-retaining ability is the curving of the leaf under water. A flocking sample fabricated by a kind of nylon flock is demonstrated to have a comparable air-retaining ability under static conditions as a Salvinia molesta leaf in its flat form.

No abstract

The plant leaf of Salvinia molesta can retain an air layer underwater due to the hydrophobic and elastic eggbeater-shaped hairs on its surface, which have potential applications in thermal insulation devices. In this research, terry fabrics are explored to mimic the air-retaining ability of the salvinia leaf for potential application in overwater life-saving appliances. The surface structure of the fabric is analyzed and the superhydrophobicity is obtained by hydrophobic treatment combined with microscale roughness brought by the fabric texture. The air volume change and the thermal insulation tests demonstrated that terry fabrics, F1 and F3, can retain an air layer on their surfaces and hold air in between the fibers and inside the loops for a long time underwater, which would provide thermal insulation and buoyancy force—the two key features of life-saving appliances.

Hydrophobic surfaces have great potential in applications in oil–water separation, super water/oil repellents, friction reducing, etc. Hydrophobic performance has been extensively investigated in view of smart textile development. Oxidized multi-walled carbon nanotubes (CNTs) and graphene oxide (GO) were grafted with perfluoro-1-iodohexane, and 10.24 and 17.65 at% fluorine contents of these functional products were obtained, respectively. The surface chemistry of the functionalized CNTs and GO were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Hydrophobic textiles were achieved by treating the functionalized CNTs and GO using a common dip-dry method. The functionalized CNTs and GO were also applied to polyvinylidene fluoride filter paper by the vacuum filtration method to form hydrophobic films. The morphologies of these surfaces were characterized by field emission scanning electron microscopy. The functional cotton fabrics showed hydrophobicity with water droplet contact angles (CAs) of 149.1°and 154.4°, respectively. The produced films showed hydrophobicity with CAs of 108° and 151°, respectively. The difference of the CA was attributed to the diversity of both the structure and the chemical composition. In future study, multifunctional materials could be created on the basis of the hydrophobic surfaces reported in this paper by combining them with other functional components, which has great potential in applications in the smart textiles.

UV-laser induced changes on surface structure and properties of Poly(ethylene terephthalate) (PET) fabric were discussed. Scanning electron microscope (SEM) observation revealed the morphological modification of PET fabrics with the ablation of 308nm excimer laser. The contact angle measurement and vertical drop test were used to find out the difference in the wetting property of the untreated and laser ablated PET fabric. Extra carboxylic radicals and increased amorphous part on the surface of the laser-ablated fabric were estimated by the attenuated total reflectance Fourier-transform infrared spectrum (ATR FT-IR) analysis. Dyeing property of the PET fabric was changed evidently by laser irradiation.