title: Controlled chain-scission of polybutadiene by the Schwartz hydrozirconation.
abstract: Controlled chain-scission of polybutadiene (PB), polyisoprene, and poly(styrene-co-butadiene), induced by bis(cyclopentadienyl) zirconium hydrochloride (Cp(2)ZrHCl), was revealed at room temperature. The chain-scission reaction of linear PB was studied by means of GPC, NMR spectroscopy, and MALDI-TOF-MS. It was confirmed that the molecular weights of degraded products were quasi-quantitatively controlled by Cp(2)ZrHCl loading, irrespective of the starting PB, whereas the microstructure of PB chains was crucial to the scission reaction. The hydrozirconation of model molecules indicated that the existence of an internal double bond in compounds with multiple double bonds was essential for chain cleavage. The chain-cleavage mechanism was proposed to involve hydrozirconation of internal double bonds in PB chains and β-alkyl elimination. Furthermore, metallocene-catalyzed chain-scission by a chain-transfer reaction was developed. It is believed that the reported chain scission offers a promising pathway for end-group functionalization by chain cleavage and presents a new application of Schwartz's reagent.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zheng
authors.forename: Yichao
authors.initials: Y
authors.lastname: Lin
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Haiying
authors.initials: H
authors.lastname: Tan
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Tang