Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Cross-linking of natural rubber at ambient temperature was successfully achieved using an organic cross-linker via click chemistry. The resulting cross-linked rubber exhibited enhanced oil resistance and improved thermal stability compared to uncross-linked natural rubber, while also retaining its biodegradability.

ABSTRACT
Natural rubber (NR), a renewable biopolymer primarily composed of cis-1,4-polyisoprene, has several applications in the tire, footwear, and adhesive industries. Depending on application areas, cross-linking is done to improve mechanical and chemical resistance or oil resistance properties. It also exhibits superior tensile strength and elasticity due to its high molecular weight and chain entanglement. Many cross-linking methods like sulfur-based cross-linking, peroxide, and radiation cross-linking still involve harsh conditions or toxic agents. This study explores a sulfur-free and low-temperature cross-linking approach using click chemistry, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC), to functionalize and cross-link functionalized NR under ambient conditions. The functionalized NR was successfully synthesized and cross-linked using CuAAC, minimizing hazardous byproducts. Structural and morphological characterizations (FTIR, XPS, FESEM, EDAX, XRD) confirmed successful modification. Thermal and swelling analyses demonstrated enhanced stability, solvent, and oil resistance. The material also served effectively as a polymer adhesion promoter for superhydrophobic leather applications. This approach presents a sustainable route for NR modification with promising industrial potential.