Self-assembly of modified cellulose nanocrystals on flexible fabric via hydrophobic force induction for versatile applications

Over the years, there has been a proliferation of superhydrophobic fabrics constructed by self-assembly techniques. However, most of these suffer from poor mechanical durability and chemical stability, while the complexity of the process severely limits their practical application in textiles with special functionalities. In this study, We have built a self-assembly coating with many advantages such as large specific surface area, ultra-fast, high particle utilization, and dense and homogeneous alignment of particles. We modified cellulose nanocrystals (m-CNCs) using a variety of hydrophobic monomers, and the modified cellulose nanocrystals were suspended in a solution of isopropanol-containing end-hydroxy polysiloxane (MSDS) and hydrogen-containing polysiloxane (PHMS). The silicone system was used to treat a cotton fabric to obtain a superhydrophobic fabric by hydrophobically inducing modified cellulose nanocrystals to self-assemble on the fibre surface. Unlike many previous studies, owing to the m-CNC particles being chemically bonded between the multilayer nanostructure and the fabric, the coating had excellent mechanical durability and remained superhydrophobic after abrasion by sandpaper or peeling with tape. In addition, the nanostructure of the coating surface trapped air in the surface pores, preventing the penetration of H+, Na+, Cl−, and OH− in liquids; thus, the fabric remained hydrophobic both under extreme solution conditions and after soaping cycle tests, showing excellent stability and cycling ability. At the same time, the breaking strength of the fabric is improved after finishing, and the wearability is almost unchanged. Coated fabrics have good potential in the fields of self-cleaning, anti-staining, oil absorption, and oil–water separation.