Fabrication of Multifunctional Chitosan Derivative with Long-Chain Alkene and Thiourea Structure and Its Application in Styrene-Butadiene Rubber/Silica Composites

In order to overcome the drawbacks of traditional rubber antioxidants with low molecular weight, such as easy migration, easy volatility, single function, and high dependence on petrochemical products, in this work, we first prepared a functional small molecular thiourea derivative (AM-DA) through the reaction of 5-amino-2-mercaptobenzimidazole (AM) and succinic anhydride (DA). Then, we fabricated a multifunctional chitosan derivative containing long-chain alkene and thiourea structure (COS-UC-AM-DA) via sequentially grafting 10-undecenoyl chloride (UC) and functional small molecular thiourea derivative (AM-DA) onto natural macromolecular polymer chitosan (COS). The acquired COS-UC-AM-DA was characterized by using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, X-ray diffraction, and antioxidant activity analysis and then as chitosan-based macromolecular multifunctional antioxidant applied in SBR/silica composites. The results suggested that COS-UC-AM-DA can improve the vulcanization efficiency of SBR/silica compounds, boost the dispersion of silica, strengthen silica-rubber interfacial interactions, and enhance the crosslinking density, mechanical properties, thermal stability, and anti-aging properties of SBR/silica composites.