Preparation of an ester-terminated telechelic polybutadiene by a two-step olefin metathesis process

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 1997-01, Vol.115 (1), p.43-50
• Main Authors: Nubel, P.O, Yokelson, H.B, Lutman, C.A, Bouslog, W.G, Behrends, R.T, Runge, K.D
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Olefin metathesis; Organic polymers; Physicochemistry of polymers; Polybutadiene; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring-opening metathesis polymerization; Telechelic
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(96)00082-9

A two-step olefin metathesis process was devised and utilized to prepare an ester-terminated telechelic 1,4-polybutadiene of high difunctional purity using readily available olefin reactants (methyl undecylenate and 1,5-cyclooctadiene or 1,5,9-cyclododecatriene). In the first step of this process, methyl undecyclenate was self-metathesized in the presence of WCl 6SnMe 4 catalyst to yield an acyclic olefinic diester, dimethyl 10-eicosene-1,20-dioate (DMED), plus ethylene. In the second step, ring-opening metathesis polymerization (ROMP) of 1,5-cyclooctadiene or 1,5,9-cyclododecatriene with DMED as a chain transfer agent was carried out using WCl 6SnMe 4 catalyst to afford the polybutadiene product. The methanol-insoluble fraction of the product, which was isolated in yields of 70–80%, consisted primarily of acyclic ester-terminated 1,4-polybutadiene species. The use of highly pure 1,5-cyclooctadiene and a low catalyst charge in the ROMP reaction yielded product in which the acyclic component was determined to be purely ester-terminated ( F n = 2.0) telechelic 1,4-polybutadiene by high-sensitivity 13C-NMR analysis. Further evidence of the high difunctional purity was obtained through chain extension of the telechelic polybutadiene to a high molecular weight polyester material by transesterification with 1,6-hexanediol.