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

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/SiO 2 , with fluorine-free hydrophobic SiO 2 nanoparticles introduced to facilitate the construction of a rough lotus-leaf-like surface structure, ultimately obtaining TPU/PMHS/SiO 2 WBMs with bead-on-string fiber binary structures and a strong water repellency. The results indicate that the TPU/PMHS/SiO 2 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/SiO 2 WBMs. This simple preparation process and unique composite structure can facilitate the design and preparation of environmentally friendly, waterproof, and breathable materials.