Open AccessFactors influencing catalytic behavior of titanium complexes bearing bisphenolate ligands toward ring-opening polymerization of L-lactide and ε-caprolactone
Author(s) -
M-T. Jiang,
Someswara Rao Kosuru,
Y. H. Lee,
W-Y Lu,
Jaya Kishore Vandavasi,
Y-C. Lai,
Michael Y. Chiang,
Chen Hy
Publication year - 2018
Publication title -
express polymer letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.695
H-Index - 72
ISSN - 1788-618X
DOI - 10.3144/expresspolymlett.2018.11
Subject(s) - caprolactone , ring opening polymerization , materials science , polymerization , titanium , catalysis , lactide , bearing (navigation) , ring (chemistry) , polymer chemistry , organic chemistry , composite material , metallurgy , chemistry , polymer , cartography , geography
A series of titanium complexes bearing substituted diphenolate ligands (RCH(phenolate)2, where R = H, CH3, o-OTs-phenyl, o-F-phenyl, o-OMe-phenyl, 2,4-OMe-phenyl) was synthesized and studied as catalysts for the ring opening polymerization of L-lactide and ε-caprolactone. Ligands were designed to probe the role of chelate effect and steric effect in the catalytic performance. From the structure of triphenolate (with one extra coordination site than diphenolate ligand) Ti complex, TriOTiOiPr2, we found no additional chelation to influence the catalytic activity of Ti complexes. It was found that bulky aryl groups in the diphenolate ligands decreased the rate of polymerization most. We conclude that steric effect is the most controlling factor in these polymerization reactions by using Ti complexes bearing diphenolate ligands as catalysts since it is responsible for the exclusion of needed space for incoming monomer by the bulky substituents on the catalyst