Lotus Leaf-Inspired Breathable Membrane with Structured Microbeads and Nanofibers

Abstract

Electrospinning is a feasible technology to fabricate nanomaterials. However, the preparation of nanomaterials with controllable structures of microbeads and fine nanofibers is still a challenge, which hinders widespread applications of electrospun products. Herein, inspired by the micro/nanostructures of lotus leaves, we constructed a structured electrospun membrane with excellent comprehensive properties. First, micro/nanostructures of membranes with adjustable microbeads and nanofibers were fabricated on a large scale and quantitatively analyzed based on the controlling preparation, and their performances were systematically evaluated. The deformation of diverse polymeric solution droplets in the electrospinning process under varying electric fields was then simulated by molecular dynamic simulation. Finally, novel fibrous membranes with structured sublayers and controllable morphologies were designed, prepared, and compared. The achieved structured membranes demonstrate a high water vapor transmission rate (WVTR) > 17.5 kg/(m2 day), a good air permeability (AP) > 5 mL/s, a high water contact angle (WCA) up to 151°, and a high hydrostatic pressure of 623 mbar. The disclosed science and technology in this article can provide a feasible method to not only adjust micro/nanostructure fibers but also to design secondary multilayer structures. This research is believed to assist in promoting the diversified development of advanced fibrous membranes and intelligent protection.

Toward low-emissivity passive heating: a supramolecular-enhanced membrane with warmth retention

“…1a). 38 The conduction parameters (applied voltage, syringe velocity, collector distance) were set at 18 kV, 1 mL h −1 and 15 cm, respectively. The few-layered MXene nanosheets were obtained by a selective etching procedure and further ultrasonic treatment.…”

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“…PVDF polymers are the most frequently used for fabricating W&B nanofibrous membranes attributed to their inherent hydrophobicity, spinnability, mechanical properties, and corrosion resistance. [55][56][57] Yang et al first developed the PVDF W&B membranes with porosity of 76.9%, providing a mass of vapor transmitting channels and resulting in the WVTR of 11.8 kg m −2 d −1 . [58] However, owing to the lack of rough structure and large pore sizes (2.2 µm), the membranes exhibited insufficient waterproofness (44.1 kPa).…”

“…[ 60,61 ] Hu et al., inspired by the micro/nanostructures of lotus leaves, constructed a structured electrospun membrane with adjustable microbeads by regulating the spinning voltage, the feed speed, the polymer solution concentration, and the conductivity of the solution. [ 57 ] Benefiting from the micro‐nanoscale rough structure, the obtained PVDF nanofibrous membranes achieved impressive WVTR of >17.5 kg m −2 d −1 , good air permeability >5 mL s −1 , and high hydrostatic pressure of 623 mbar. Furthermore, Jiang et al.…”

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