“…The living polymerization of butadiene with Nd-based catalysts without chain transfer and termination reactions could be achieved only at extremely low temperature (−70 °C), and cis -PB with relatively high number-average molecular weight ( M n ) of >410 kg·mol –1 was obtained . The end-group-functionalized cis -PBs could be achieved by terminating the living cis -PB chains after coordination polymerization by adding appropriate functional agents such as epoxy, , ketone, ketimine, isocyanate compounds, carboxyl compounds, halogen, aldehyde, amide, ester, imidazolidinone, pentamethyl siloxane, and 3-glycidoxypropyltrimethoxysilane. , Unfortunately, the resulting end-group-functionalized cis -PBs with relatively low functionality were obtained due to the complex chemical mechanism and self-termination reaction. − On the other hand, the reversible chain transfer polymerization of butadiene with an Nd-based catalyst system was firstly reported by Nuyken and co-workers , and has been used to synthesize block copolymers and end-group-functionalized polymers . Polymer chains carrying hydroxyl groups introduce hydrogen bonds, which has been recognized as an effective way to build self-healing materials.…”