Fiber-based photothermal, UV-resistant, and self-cleaning coatings fabricated by silicon grafted copolymers of chitosan derivatives and gallic acid

Superhydrophobic and hydrophobic properties are generally created by adopting low surface free energy materials. Therefore, most studies have focused on creating surface hydrophobicity by using hydrophobic or fluorinated materials. However, few studies are reported on realizing surface hydrophobicity by directly introducing hydrophilic molecules, which is also a challenge. Herein, with platinum nanozyme as the catalyst, the novel hydrophobic coatings have been rapidly gained via anchoring the polymer of hydrophilic gallic acid and chitosan or chitosan quaternary ammonium salt onto cotton fabric surface. Notably, the novel hydrophobic coatings exhibit significant advances compared with conventional hydrophobic ones created by utilizing fluorinated or hydrophobic materials, which breaks the limitation of employing low surface energy materials for gaining surface hydrophobicity. Subsequently, the sodium methyl silicate was grafted on the polymer's coatings to strengthen surface hydrophobicity and the abrasion resistance of hydrophobicity. Interestingly, the heating could induce the hydrophilicity of cotton fabric to recover to hydrophobicity. Moreover, the hydrophobic coatings also possess good photothermal conversion, UV resistance, and anti-oxidation activity for self-cleaning application and oil water separation. Briefly, the present work may open a new direction for preparing novel hydrophobic coatings by combining gallic acid and chitosan-based macromolecular carbohydrates.