State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
University of Science and Technology of China, Hefei, 230026, China.
Macromol Rapid Commun. 2020 May;41(10):e2000038. doi: 10.1002/marc.202000038. Epub 2020 Apr 13.
Streoregular poly(vinyl alcohol) is hard to obtain because vinyl alcohol is unstable relative to its tautomer acetaldehyde, and the monomer precursor vinyl ester is poisonous to the coordination catalyst. Herein, the coordination polymerization of 2-vinyl-2,1-borazanaphthalene (BN2VN) is reported by the linked or unlinked half-sandwich ligands attached scandium precursors ((FluSiMe )Sc(CH SiMe ) (THF) (THF = tetrahydrofuran, 1), (FluCH CH -NHC-R)Sc(CH SiMe ) (THF) (R = mesityl 2, Pr 3, Me 4), and (FluCH Py)Sc(CH SiMe ) (5) for the first time. Among these precursors, complex 5 converts 600 equivalents of BN2VN into polymer within 5 min to reach an activity as high as 8.99 × 10 g mol h . The resultant products show excellent syndiotacticity and melting temperatures above 300 °C, which can be transferred to syndiotactic poly(vinyl alcohol) with 90% rr triad content by postpolymerization oxidation.
Streoregular 聚（聚乙烯醇）很难获得，因为相对于其互变异构体乙醛，乙烯醇是不稳定的，并且单体前体乙烯酯对配位催化剂有毒。在此，通过连接或未连接的半夹心配体连接的钪前体报道了 2-乙烯基-2,1-硼杂萘（BN2VN）的配位聚合（（FluSiMe ）Sc（CH SiMe ）（THF）（THF=四氢呋喃，1），（FluCH CH -NHC-R）Sc（CH SiMe ）（THF）（R=mesityl 2，Pr 3，Me 4）和（FluCH Py）Sc（CH SiMe ）（5）。在这些前体中，配合物 5 在 5 分钟内将 600 当量的 BN2VN 转化为聚合物，活性高达 8.99×10 g mol h 。所得产物表现出极好的间同立构规整性和高于 300°C 的熔融温度，通过聚合后氧化可将其转化为间同立构含量为 90% rr 三联体的聚（聚乙烯醇）。
