Bionic lotus‐leaf‐structured fluorine‐free polyurethane by combining electrospinning and electro‐spraying for waterproof and breathable textiles

Abstract

Developing environmentally friendly and high‐performing viable waterproof and breathable membranes (WBMs) is critical but significantly challenging. Herein, we combine electrospinning and electro‐spraying methods. First, elastic thermoplastic polyurethane (TPU) is used as the polymer, and poly(methylhydrosiloxane) (PMHS) with low surface energy is introduced to prepare TPU/PMHS fiber‐based membranes by electrospinning. Electro‐spraying is performed using a dilute solution of TPU/PMHS/SiO2, with fluorine‐free hydrophobic SiO2 nanoparticles introduced to facilitate the construction of a rough lotus‐leaf‐like surface structure, ultimately obtaining TPU/PMHS/SiO2 WBMs with bead‐on‐string fiber binary structures and a strong water repellency. The results indicate that the TPU/PMHS/SiO2 WBMs comprise a three‐dimensional porous structure formed by randomly arranged fibers and a lotus biomimetic structure consisting of bead‐like fibers, providing the membrane with excellent mechanical properties and waterproof breathability, including a tensile strength of 15.8 MPa, static water pressure of 33 kPa, water vapor transmission rate of 5169 g m−2 d−1, and contact angle of 142°. Additionally, the fiber membrane exhibits an excellent strain recovery after 1000 cycles of cyclic stretching under 100% strain, verifying the excellent elastic properties of the TPU/PMHS/SiO2 WBMs. This simple preparation process and unique composite structure can facilitate the design and preparation of environmentally friendly, waterproof, and breathable materials.