Polymerization of 2,2 ''''-Dimethyltrimethylene Carbonate by Lutetium Complexes Bearing Amino-Phosphine Ligands
writer：Liu, B; Cui, DM
keywords：polycarbonates， catalysts， amino-phosphine， lutetium complex
source：期刊
specific source：http://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=43&SID=V2hxdX
Issue time：2009年
A series of lutetium alkyl, amino,
and guanidinato complexes based upon an amino-phosphine ligand
framework had been prepared. Thesecomplexes were applied to initiate
ring-opening polymerization of 2,2''''-dimethyltrimethylene carbonate (DTC). The
type of the initiator significantly influenced the catalytic activity of these complexes in
a trend as follows: alkyl approximate to guanidinate > amide, whereas the complexes with
flexible backbone between P and N atoms within the ligand exhibited higher
activity than those with rigid backbone. The isolated PDTC had bimodal-mode
molecular weight distribution. The molecular weights of each fraction increased
linearly with the conversion, indicating that there might be two active
species. This had been confirmed by analyses of oligomeric DTC living species
and oligomer with NMR technique as the metal-alkoxide and the four-membered
metallocyclic lactate. Kinetic investigation displayed that the polymerization
rate was the first order with the monomer concentration. (c) 2009 Wiley Periodicals,
Inc.