Catalytic Activity of a Titanium(IV)/Iron(II) Heterometallic Alkoxide in the Ring‑Opening Polymerization of ε-Caprolactone and rac-Lactide

Journal of the Brazilian Chemical Society

Siddhartha O. K. Giese¹  Cristiano Egevardt¹  André Luis Rüdiger¹  Eduardo L. Sá¹  Thiago Alessandre Silva¹  Sônia F. Zawadzki¹  Jaísa F. Soares¹  Giovana G. Nunes¹ 

关键词: heterometal alkoxide;    ring opening polymerization;    ε-caprolactone;    rac-lactide;    iron(II);    titanium(IV);   

DOI  :  10.5935/0103-5053.20150214

来源: SciELO

【 摘 要 】

The activity of the heterometallic alkoxide [FeCl{Ti2(OiPr)9}] (1) towards polymerization of rac-lactide (rac-LA) and ε-caprolactone (ε-CL) was investigated in toluene solution and in bulk at various temperatures, monomer/heterometallic alkoxide molar ratio and reaction times. The alkoxide 1 was active in solution for ε-CL and in bulk for both monomers. Polymers were obtained in good yields with molecular weights ranging from 3890 to 15000 g moL-1 and polydispersity indexes (PDI) values varying from 1.3 to 2.5. Based on the 1H nuclear magnetic resonance (NMR) end-group analysis of polymers, a coordination-insertion mechanism was suggested for both monomers. The average number of growing chains per molecule of initiator (4 to 5 for rac-LA and 7 to 8 for ε-CL) indicates that both bridging and terminal isopropoxides are active initiating groups. Kinetic studies with ε-CL indicated that the polymerization rate is first order with respect to monomer concentration. The catalytic properties of 1 were compared to those found for other titanium(IV) and iron(II) complexes using ε-CL as a model monomer.

【 授权许可】

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