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Constrained geometry scandium permethylindenyl complexes for the ring-opening polymerisation of l- and rac-lactide.

Author(s) Diteepeng, N.; Buffet, J.C.; Turner, Z.R.; O'Hare, D.
Journal Dalton Trans
Date Published 2019 Nov 14
Abstract

The synthesis and characterisation of constrained geometry scandium permethylindenyl chloride, aryloxide and borohydride complexes SB(N,I*)Sc(Cl)(THF) (1), SB(N,I*)Sc(O-2,6-Pr-CH)(THF) (2), SB(N,I*)Sc(O-2,4-Bu-CH)(THF) (3) and SB(N,I*)Sc(BH)(THF) (4) are reported. The activity of complexes 1-4 as initiators for the ring-opening polymerisation (ROP) of l- and rac-lactide is presented. The ROP of l- and rac-lactide using complexes 2 and 3 show first-order dependence on monomer concentration, and produced isotactic polylactide (PLA) and moderately heterotactic PLA (P = 0.68-0.72), respectively. Good agreement between experimental and theoretical molecular weights of PLA (M) and relatively narrow dispersities (M/M < 1.20) were obtained. Complex 4 showed higher activity for ROP of l- and rac-lactide than 2 or 3, with second-order dependence on monomer concentrations. However, poorly controlled molecular weights and lower heteroselectivity (P = 0.61-0.67) were observed. The effect of temperature and catalyst concentration for the ROP of l-lactide using 2 and 3 was also studied.

DOI 10.1039/c9dt03450a
ISSN 1477-9234
Citation Diteepeng N, Buffet J-, Turner ZR, O'Hare D. Constrained geometry scandium permethylindenyl complexes for the ring-opening polymerisation of l- and rac-lactide. Dalton Trans. 2019;48(42):16099-16107.