Facile and efficient in-situ end-functionalization of neodymium-based polybutadiene by isocyanate via a coordinative chain transfer polymerization strategy

Tapping facile and efficient strategies for in-situ end-functionalization of polydiene elastomers has been pursued for scientists for decades. This has been especially prominent for Ziegler-Natta type catalytic systems , because they hold great potential for future large-scale industrializations. In this report, through using a newly emerged method of coordinative chain transfer polymerization (CCTP), we introduce a simple and convenient method to efficiently end-functionalize neodymium-based polybutadienes by in-situ addition of isocyanate or isothiocyanate compounds. These two types of substrates performed high reactivities with η 1 -allyl-Al capped polybutadienyl chain-ends, that were generated from fast and reversible chain transfer reactions , giving high functionalization efficiencies (up to 97.1 %). The high functionalization efficiencies were also applicable to isocyanate or isothiocyanate substrates bearing different functionalities, showing a broad scope capability. Moreover, such a functionalization process was not influenced by the viscosities of the reaction system, as revealed from the kinetic studies that linear relationship was obtained between M n s and various [BD]/[Nd] ratios, implying again the high reactivities of the isocyanate or isothiocyanate compounds. Due to the incorporation of amide or thioamide functional group into the chain-ends, the corresponding polybutadienes showed much improved surface properties and performed higher mechanical properties than unfunctionalized counterparts for raw rubber matrix. Regarding the vulcanizate , chain-end functional groups could also result in much improved filler dispersion and stronger interaction between rubber and filler particles , which eventually gave rise to better mechanical properties, inducing higher tensile strength , more toughness, and greater tear strength .