Synthesis of high cis-1,4 polybutadiene with narrow molecular weight distribution via a neodymium-based binary catalyst
2018
Liu, Jie | Fan, Xiaodong | Min, Xin | Zhu, Xiuzhong | Zhao, Na | Wang, Zichao
This work explores the synthesis of polybutadiene (PB) with high cis-1,4 unit content and narrow molecular weight distribution using a neodymium-based complex, consisting of neodymium(iii) trifluoromethane sulfonate (Nd(CF₃SO₃)₃) and coordinated with tris(2-ethylhexyl)phosphate (TOP). The complex's composition and structure are characterized by elemental analysis, XPS and FT-IR. Combined with Al(i-Bu)₃, a binary catalyst is obtained and then applied to initiate the polymerization of butadiene. Results indicate that the catalyst system displays a high catalyst activity and the product polymer (PB) features a high cis-1,4 content (98.8%) and a remarkably narrow molecular weight distribution (Mw/Mₙ = 1.32). Compared with PB initiated by the current well-studied catalyst Nd(CF₃SO₃)₃*3TBP/Al(i-Bu)₃, the Nd(CF₃SO₃)₃*3TOP allows significantly narrowing the molecular weight distribution of the PB, because the Nd(CF₃SO₃)₃*3TOP is more easily dissolved in hexane. Therefore, butadiene was polymerized in a homogenous system and each monomer's polymerization was initiated in the single molecular state.
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