Fibrous materials with high light transmittance exhibit great potential in a wide range of applications; unfortunately, fabrication of such materials still remains a challenge due to the strong light scattering caused by the rough fibrous structure and the voids between fibers. Window screens are commonly used in our daily life, and their unique woven structure ensures excellent mechanical properties, while the voids between wires allow light to pass through. By learning from the architecture of window screens, we proposed a novel patterned electrospinning approach with window screen like wire meshes as collectors to deposit fibers with anisotropic thickness gradients and further to improve the optical properties. The results indicated that the obtained fibrous mats closely copied the structure of the wire meshes, and exhibited unique thickness anisotropy with most of the fibers densely packed on the wires in a small area, while very few fibers sparsely suspended in the voids over a large area. Owing to the large area of the thin region within fibrous mats, the overall light transmittance of such a well-organized mat was greatly improved as compared with that of an isotropous mat. Furthermore, by carefully investigating the microstructure of the fibrous mats and simulating the electric field distribution with the software Comsol Multiphysics, a novel needle array collector with an ultra large area of voids was designed to achieve optimal light transparency. Finally, as proof of concepts, we investigated the potential use of transparent fibrous mats as a visual wound dressing and a window dust filter, respectively.
Kai Gou,Lei Wang,Minghui Wei,Jingtao Jiang,Gengsheng Weng
Morphing a two-dimensional (2D) plate into customized three-dimensional (3D) structures with complex curvatures is of great importance for developing the next generation of soft robotics, flexible devices, and sensors. Yet, the practical application of shape-morphing materials remains challenging due to the material’s inhomogeneous or discontinuous design. Herein, we demonstrate a biomorphogenesis-inspired paradigm that utilizes the ultraviolet mapping-based thickness gradient (UVM-TG) design for the shape transformation of bilayer-structured polymer sheets composed of a hydrogel layer and a hydrophobic polymer layer. The hydrophobic polymer layer as the passive layer is laser-engraved to create the thickness gradient distribution, which programs the dehydrative-shrinking-driven 3D shape transformation of the bilayer polymer sheets to deform into 3D structures with complex Gaussian curvatures, e.g., gourd and roadster. These 3D structures without uncontrollable surface buckling and wrinkles during those nonzero Gaussian curvature shape transformations exhibit reversible shaping/flattening switchability. Our UVM-TG design strategy, which does not require the inhomogeneous or discontinuous design of shape-morphing materials, establishes a facile strategy for fabricating shape-morphing materials.
The gradient surface shows enormous potential in the development of tissue engineering, biosensor, microfluidic control, and particle sorting. In this work, a poly(polyethyleneglycol methacrylate) (poly(PEGMA)) gradient surface was prepared through surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-AGRET ATRP). The effect of various parameters on the thickness growth of poly(PEGMA) film were analyzed, among which the excessive reducing agent was utmost important. The reducing agents supported the regeneration of Cu I and eliminated the disturbance of air, maintaining the "living polymerization" of poly(PEGMA) up to 73.1 nm under tested conditions. The physicochemical properties of the fabricated surfaces were characterized by ellipsometry, X-ray photoelectron spectroscopy, water contact angle. The thickness slope of gradient poly(PEGMA) was controllable in a nanoscale range. The gradient surface was further grafted with CRGD (Cys-Arg-Gly-Asp) peptides onto the poly(PEGMA- co -[glycidyl methacrylate]) blocks via the ring-opening reaction between epoxy and amino groups, which showed a gradient change in water contact angle and adhesion of endothelial cells.
危险品化学品经营许可证（带存储）