Dynamic covalent chemistry (DCC), exemplified by imine chemistry, has unlocked unprecedented opportunities for designing polymeric materials with tunable structures and multifunctionality. Building upon this foundation, our recent work leverages imine-based dynamic covalent systems to address two critical challenges in materials science: (1) Quaternary Nanocomposites: By incorporating cleavable dynamic covalent bonds at the “root” of polymer-grafted nanoparticles, we achieved repeated grafting, degrafting, and regrafting of polymer brushes on nanoparticle surfaces. This strategy enables the fabrication of nanocomposites with multiple chemically distinct polymer grafts while avoiding phase separation—a breakthrough for modular and adaptive hybrid materials. (2) Water-Degradable Networks: Utilizing a guanidine-mediated Mannich-type reaction, we constructed dynamic polymer networks (films and hydrogels) from low-cost reactants (guanidine hydrochloride, aldehydes, and diamines). These materials exhibit stimuli-responsiveness, autonomous self-healing, and complete degradation in room-temperature water within 30 days—a rare combination of robustness and degradability. The inherent reversibility of dynamic covalent bonds not only facilitates reprocessability but also provides a pathway toward a sustainable future. Our findings highlight how DCC principles can bridge the gap between performance-driven engineering and sustainability. Looking ahead, these works opens avenues for designing “programmable” materials with on-demand degradation kinetics, particularly for transient electronics, eco-friendly packaging, and biomedical devices. By integrating molecular-level dynamism with macroscopic functionality, we envision a new paradigm where advanced materials coexist harmoniously with circular economy principles.