In-situ polymerized zinc ions chelated Si-C-N cenospheres-based geopolymeric coating constructed by incorporating β-cyclodextrin and dopamine for flame-retarding plywood

Preparing halogen-free and efficient bio-flame retardants by recycling industrial solid waste is crucial for creating an environmentally friendly human settlement. Herein, β-cyclodextrin(β-CD) and dopamine(DA) are employed to chelate zinc ions (β-CD@Zn@DA) involved in cenospheres-based geopolymeric coating for further flame-retarding plywood. The results show that an appropriate dosage of β-CD (1.2 g, 1.00 wt%) improves the flame retardancy of the geopolymeric coating, and the peak heat release rate decreases from 107.17 kW·m−2 to 66.04 kW·m−2, the flame retardancy index increases from 1.00 to 1.41. Meanwhile, due to hydrogen bonding cross-linking and chelation of zinc ions, the coating is transformed into a dense and non-flammable ceramic-like blocking layer during firing to prevent heat or mass transfer. Furthermore, the pyrolysis kinetics identify that the Z.-L.-T. three-dimensional diffusion–reaction model governs the coatings’ pyrolysis, and an appropriate β-CD makes the pyrolysis Eα climb from 186.08 to 237.41 kJ·mol−1 at 980 ∼ 740 °C, corresponding to the resilient residues for blocking heat and fire. Therefore, in-situ polymerized zinc ions, chelated β-CD, and DA for facilely designing Si-C-N hybrid flame-retarding coating is explored, promoting the recycling of industrial solid waste and the development of more sustainable building materials.