Titanium-salen complexes as initiators for the ring opening polymerisation of rac-lactide.
A family of bis(iso-propoxide) titanium(IV) complexes supported by tetradentate Schiff base (salen) ligands has been synthesised and characterised, including a structural determination of N,N'-bis(6'-methylenimino-2',4'-di-tert-butylphenoxy)cyclohexyl-(1R,2R)-diamino titanium(IV) bis(iso-propoxide). Their suitability for initiating the ring-opening polymerisation of rac-lactide has been investigated. Polymerisation activities are shown to correlate with the electronic properties of the substituents within the salen ligand. In contrast to aluminium-salen initiators, electron-withdrawing substituents on the Schiff base ligand have a detrimental influence upon polymerisation activities, whereas the use of electron-donating alkoxy-functionalized ligands has allowed the highest recorded activity to date for a titanium-based initiator.
Gregson
Charlotte K A
CK
Imperial College London, Department of Chemistry, South Kensington Campus, London, UK SW7 2AZ.
Blackmore
Ian J
IJ
Gibson
Vernon C
VC
Long
Nicholas J
NJ
Marshall
Edward L
EL
White
Andrew J P
AJ