Cross-linking is a research area in chemistry and materials science that involves the formation of covalent bonds between polymer chains, creating a network structure. This process can improve the mechanical properties, stability, and durability of materials, making them more resistant to degradation and deformation. Cross-linking can be achieved through various methods, such as thermal, chemical, or radiation-induced cross-linking. This research area is important in the development of materials for various applications, including in the fields of adhesives, coatings, biomaterials, and electronics.