Exploring the unique characteristics of natural rubber induced by coordination interaction between proteins and Zn2+

The properties of synthetic polyisoprene (PI) cannot rival that of NR, although synthetic PI can achieve similar molecular chain structure (for example molecular weight and molecule chain configuration) to that of NR. It is still a challenge to explore the reason why NR owns superior comprehensive properties. Here our group focuses on the problem why non-rubber components can accelerate crosslinking process from molecular level. From macroscopic perspective, we find that proteins change the crosslinking behaviors and decrease activation energy of crosslinking process. From microscopic perspective, the formation of coordination interaction between Zn2+ and amide bonds of proteins is confirmed, which improves solubility of Zn2+ in matrix and further contributes to crosslinking reaction. In this study, the formation of coordination interaction between proteins and Zn2+ is considered as one of the reasons why NR owns excellent mechanical properties. This article also provides more insightful understanding toward the relationship among structure, components, and properties of NR.