Sustainable Structural Hot-Melt Adhesives Enabled by Functionalized Crystalline Lamellae

Conventional hot-melt adhesives (HMAs) suffer from low shear strength and poor recyclability, limiting their structural applications. Here, a sustainable HMA system is developed from renewable building blocks that combines strong adhesion with closed-loop chemical recyclability. Incorporating polar functional groups into crystalline lamellae enables efficient stress transfer through rigid domains, achieving a balance between cohesive and adhesive forces. The resulting sulfur-based polymers exhibit shear strengths above 14.7 MPa on wood and 15.1 MPa on stainless steel, along with excellent oxygen and water vapor barrier properties suitable for microelectronic encapsulation. Moreover, these materials can be fully depolymerized from a mixed materials system under mild hydrogenation to regenerate the original monomers. This work establishes a design strategy for structural HMAs that unifies high performance, sustainability, and recyclability.