Sustainable cellulose nanocrystal based hydrophobic coatings with excellent self-cleaning and high thermal stability for multi-scenario applications

Paper-based packaging is widely applied for reducing the application of nonbiodegradable fossil-based polymers because of the growing environmental problems. However, paper significantly weakened its mechanical strength in a humid environment because of its hygroscopic nature, and traditional nonbiodegradable polymer coated hydrophobic paper caused microplastics after being discarded. This work developed sustainable cellulose nanocrystals (CNCs) based hydrophobic coatings (DPCs) with self-cleaning properties via self-polymerization of dopamine (DA) and subsequent grafting dodecyltrimethoxysilane (DTMS). The as-produced DPC-3 coating had the highest water contact angle (WCA) of 127.1 ± 1.5° with high water dispersion stability among the other samples because introducing DTMS could significantly transform the hydrophilicity of PDA@CNC to hydrophobicity. Compared to pure CNCs, DPC-3 exhibited excellent thermal stability, and its maximum decomposition temperature (Tmax) improved by 32.5 °C. The obtained DPC-3 powder could be well mixed with chemical solutions and applied to the various substrate surfaces to form hydrophobic and self-cleaning coatings for versatile and promising multi-scenario applications in the waterproofing of paper-based express boxes, fabrics, and paper, as well as self-cleaning of glass. Such improved hydrophobic and high-performance DPCs coatings showed promising choices to reduce the use of nonbiodegradable polymer coating. •Cellulose nanocrystals based hydrophobic coatings (DPC) via reacting with DA and DTMS.•DPC-3 coating had highest water contact angle of 127.1 ± 1.5° with good dispersion stability.•DPC-3 exhibited excellent thermal stability with Tmax increament range of 32.5 °C.•Hydrophobic and self-cleaning DPC-3 coatings showed versatile multi-scenario applications.