Closed-Loop Recyclable, Self-Catalytic Transesterification Vitrimer Coatings with Superior Adhesive Strength, Fire Retardancy, and Environmental Stability
Cheng Wang, Guofeng Ye, Qi Zhang, Hao Wang, Siqi Huo, Zhitian Liu
Abstract
The nondegradability, nonreusability, and flammability of epoxy coatings have brought serious environmental and safety issues. Herein, a multifunctional, fire-retardant epoxy vitrimer coating (DCNC/45PETO) was prepared via curing bis(2,3-epoxypropyl)cyclohex-4-ene-1,2-dicarboxylate (DCNC) with a well-designed phosphaphenanthrene-containing polyethylenimine (PETO) at room temperature. DCNC/45PETO exhibits excellent adhesion to different substrates, with a high adhesive strength of 7.9 MPa on wood, outperforming previous wood coatings/adhesives. The DCNC/45PETO coating endows wood with excellent fire retardancy, including a high limiting oxygen index of 34.0% and a vertical burning (UL-94) V-0 rating. DCNC/45PETO demonstrates durable adhesion and fire-retardant performances in harsh environments. The self-catalytic transesterification within the DCNC/45PETO network effectively avoids the application of extra toxic catalysts, and this coating can be reused for at least 5 times in mild conditions without compromising its performances. This study provides an innovative design strategy for creating multifunctional vitrimer coatings, showing great application potential in the construction field.