Synthesis and properties of terminal aminoized polyisoprene for natural rubber alternatives

<p indent="0mm">A cationic rare earth catalytic system was used to add HAl<italic>ⁱ</italic>Bu₂ or Al<italic>ⁱ</italic>Bu₃ at the end of isoprene polymerization, improve the reactivity of the polymer terminal through chain transfer, and then react with a series of modifiers such as 3-aminobenzonitrile to obtain terminal aminoized polyisoprene. ¹H NMR and 2D DOSY ¹H NMR spectra demonstrated the successful grafting of the modifier, and the product had a <italic>cis</italic>-1,4 selectivity &gt;98% while maintaining a narrow molecular weight distribution (PDI &lt; 2). However, the polymerization system without alkyl aluminum at the end of polymerization makes it difficult to perform a terminal grafting reaction with the modifier. Compared with rare earth isoprene rubber, the carbon black formula vulcanizate modified by 3-aminobenzonitrile has achieved a significant increase in stress at 300% while maintaining high strength and elongation at break. The tensile strength is <sc>26.12 MPa</sc> and the stress at 300% can reach <sc>19.66 MPa.</sc> It is speculated that the amino group at the end of the chain reacts with the carboxyl group on the surface of carbon black to form amide bonds and ionic bonds, and forms hydrogen bonds with hydroxyl and other oxygen-containing functional groups. The joint action of covalent bonds, ionic bonds and hydrogen bonds enhances the physical adsorption capacity of rubber molecular chains on the surface of carbon black, thus improving the interface interaction between rubber and carbon black. This strategy provides a new idea for the development of tread rubber for aviation tires.