French scientists develop super flexible biomimetic membrane materials for smart fabrics

The soft elastic material has good flexibility, large deformation and high energy conversion efficiency, and has great application requirements in the field of smart fabrics. However, the preparation of soft elastomeric systems with long life, low cost and good biocompatibility is still a challenging task. In nature, spider silk is a representative of the excellent properties of natural fibers, which can exhibit ultra-high stretchability. Even some varieties of spider silk can stretch 100 times without breaking. In fact, this is sticky with spider silk. The fibers in the form of "pre-stored" in various forms are inseparable. In addition, animal cells also have excellent flexibility, they are achieved by membrane folding and microvilli structure, for example, macrophages can expand their surface area by 5 times to engulf large microorganisms or cell debris, which is actually with cells. Membrane folds are directly related to the "pre-stored" film in the form of microvilli. The above-mentioned high-elasticity system in nature provides an important inspiration for scientists to design high-performance stretchable soft materials. Researchers such as Arnaud Antkowiak of the French National Academy of Sciences (CNRS) simulated cell wrinkle and villus strain buffer structures, using polyvinylidene fluoride-CO-hexafluoropropylene (PVDF-HFP) as a material, by perfusing in nanofiber membranes. The wetting liquid drive builds a super-flexible material with reversible deformation. The research team first prepared PVDF-HFP nonwoven film by electrospinning technology. The maximum resistance to deformation of the nanofiber membrane was only 30% before further processing. In order to simulate the surface tension to drive the stretching of the lower cortex actin layer, the researchers further infused the wetting liquid (silicone oil) into the fiber membrane, and the resulting capillary force stored its additional membrane components in the folds and grooves. Forming a network of veins, thereby imparting ultra-high stretchability to the PVDF-HFP film material. The PVDF-HFP membrane materials were further prepared into planar, columnar and spherical shapes. Studies have shown that different membrane materials exhibit similar wrinkle behavior driven by liquid capillary action, but there are subtle differences in force behavior and deformation scale. Among them, the spherical membrane material exhibits good stability in a 10-fold volume expansion/contraction cycle test of up to 100,000 times. The theoretical research results help people understand the stress buckling behavior of soft elastic materials from the perspective of microstructure deformation, and provide reference strategies for the design and construction of super flexible materials, which has important guiding significance for the development of a new generation of flexible smart textiles. Related papers published in Science on Capillarity-induced folds fuel extreme shape changes in thin wicked membranes.