kruislinker

A kruislinker, which translates from Dutch to "cross-linker," is a substance or a process that creates bonds between different polymer chains or molecules. These cross-links form a three-dimensional network structure, significantly altering the material's properties compared to its uncross-linked state. The process of cross-linking is often referred to as curing or vulcanization, especially in the context of rubber.

Cross-linking can occur through various mechanisms, including chemical reactions, thermal treatment, or irradiation. Chemical cross-linking often involves adding specific reagents that react with functional groups on the polymer chains, forming covalent bonds. For instance, sulfur vulcanization is a classic method for cross-linking rubber, using sulfur atoms to bridge polymer chains. Thermal cross-linking involves heating the material to activate chemical reactions that lead to the formation of cross-links. Radiation cross-linking utilizes high-energy radiation, such as gamma rays or electron beams, to generate free radicals on polymer chains, which then combine to form cross-links.

The introduction of cross-links profoundly affects a material's physical and mechanical characteristics. Typically, cross-linked polymers exhibit increased strength, rigidity, thermal stability, and resistance to solvents and creep. Conversely, cross-linking generally reduces a material's ductility and elasticity if the cross-link density is too high. The extent of cross-linking can be controlled to tailor the material's properties for specific applications. Examples of materials that undergo cross-linking include thermosetting plastics, elastomers, and hydrogels. These materials find applications in diverse fields such as automotive components, adhesives, coatings, and biomedical devices.