Bio-Based Monoepoxy-Terminated Polysiloxane-Modified Coating for Hydrophobic and Oil-Resistant Paper

Nondegradable waste has caused a series of environmental issues, including soil pollution and marine microplastics. In this study, we report a green, recyclable, and easily available material for preparing hydrophobic and oil-resistant packaging paper. A grafting dispersion of monoepoxy-terminated polysiloxane (mono-PDMS-E) grafted chitosan (CS) and cellulose nanofibers (CNFs) was prepared via a one-pot method. The CNFs-CS/mono-PDMS-E complex was cast into films, and its successful preparation was confirmed by ¹H NMR and FTIR analyses. With increasing CNF content, the water and oil contact angles of the CNFs-CS/mono-PDMS-E films decreased, while their thermal stability and mechanical properties improved. The CNFs-CS/mono-PDMS-E was then applied as a coating for food packaging paper. When CNF content was 3%, and the coating weight was 4.85 ± 1.2 g/m², the coated paper (CNFs-CS/mono-PDMS-E-Paper) exhibited excellent hydrophobicity (Cobb₆₀: 20.48 g/m²) and oil resistance (Kit rating: 9.5/12). The whiteness, tensile strength, and tear index of the paper were measured before and after coating. Surface elemental analysis was performed via XPS, and a structural model was constructed. SEM was used to analyze the effect of CNF addition on microphase separation in the CNFs-CS/mono-PDMS-E films and the changes in paper porosity after coating. The recyclability of the pulp was verified by repulping and washing treatments on the CNFs-CS/mono-PDMS-E-Paper (CNFs = 7%) sample. This study provides a perspective for reducing soil pollution and marine microplastics. The CNFs-CS/mono-PDMS-E-Paper is expected to promote sustainable development due to its readily available, green, and recyclable features.