Hydrophobic and Anticorrosive Properties of Nano‐ <scp> SiO ₂ </scp> ‐Modified Castor Oil‐Based Polyurethane

ABSTRACT In order to enhance the hydrophobic and anticorrosive properties of castor oil‐based polyurethane (CO‐PU), γ‐glycidyloxypropyltrimethoxysilane (KH‐560, an epoxy‐functional silane) was selected for surface modification of Nano‐SiO 2 . The modified Nano‐SiO 2 was incorporated into an organosilane‐modified CO‐PU (CKPU) matrix to produce a series of nano‐SiO 2 ‐modified castor oil‐based polyurethane composites (CKPU‐Nano). While previous studies (e.g., Xiaoyan Gao et al. on synthesis, Hao‐Jie Song et al. on tribology, and Xiaoli Wei et al. on super‐hydrophobicity) have explored polyurethane/SiO 2 nanocomposites, this work uniquely focuses on a biomass‐derived polyurethane substrate for eco‐friendly coating applications. The investigation was characterized by a combination of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to examine the effects of varying Nano‐SiO 2 mass ratios on the properties of CKPU‐Nano, including tensile properties, water contact angle, gloss, electrochemistry, and resistance to liquid media. The findings demonstrated that the composite performance was optimal with 1 wt% Nano‐SiO 2 incorporation. The composite coating exhibited a maximum water contact angle of 93°, a corrosion potential ( E cor ) of −0.345 V, a corrosion current density ( I corr ) of 1.88 × 10 −7 A/cm 2 , and a polarization resistance ( R p ) of 122.46 kΩ cm 2 after immersion in a 3.5% NaCl solution. These findings provide a research strategy for expanding the application of sustainable, biomass‐based polyurethanes with high‐performance hydrophobic and anticorrosive properties.