Green and sustainable itaconic acid-based vitrimers with rapid stress relaxation, superior fire safety, and recyclability via synergistic roles of multiple dynamic bonds

Abstract

The construction of bio-based vitrimers with tailored functions by strategic utilization of renewable raw materials and their derivatives is eagerly anticipated. However, achieving rapid dynamic bonds exchange and intrinsic flame retardancy without traditional flame retardant elements faces a critical challenge. Here, we precisely integrated a synergistic covalent network in itaconic acid-based EIA/TA/BAS (ETB) vitrimers enabled by the complementary functions and synergy of dynamic ester, disulfide, and siloxane bonds. The results showed that ETB exhibited superior shielding capabilities for both UV (≈0% transmittance) and visible light (≈3% transmittance). Moreover, ETB achieved extremely rapid dynamic bonds exchange, evidenced by complete stress relaxation within 8 s at 180 °C, and exhibited excellent shape memory (recovery in ≈60 s). Meanwhile, the rapid bonds exchange imparted ETB with recyclability and robust welding (loading of 500 g). The unique ester and disulfide bonds derived from bio-based compounds imparted ETB with rapid chemical degradation (1 M NaOH, 80 °C, 1 h). Notably, ETB achieves intrinsic flame retardancy of UL-94 V-1 level, through the synergistic action of the siloxane and disulfide bonds, which release non-flammable gases and promote silicon–sulfur synergistic char formation. This work provides a simple and cost-effective strategy for developing functional polymers based on the inherent structures of bio-based monomers.