Titanium complexes bearing 2,6-Bis(o-hydroxyalkyl)pyridine ligands in the ring-opening polymerization of L-Lactide and ε-caprolactone

Feng Jie Lai, Tsai Wen Huang, Yu Lun Chang, Heng Yi Chang, Wei Yi Lu, Shangwu Ding, Hsuan Ying Chen, Chien Chih Chiu, Kuo Hui Wu

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3 Scopus citations

Abstract

A series of titanium (Ti) compounds bearing 2,6-bis(o-hydroxyalkyl)pyridine ligands were synthesized and investigated as catalysts for the ring-opening polymerization of ε-caprolactone (CL) and L-lactide (LA). The Ti complexes with electron-withdrawing groups in pyridine rings or steric bulky groups in hydroxymethyl groups reduced the catalytic activity in CL and LA polymerizations, and MeLPh-TiOPr2 exhibited the highest catalytic activity ([CL] = 0.5 M, [CL]:[Cat] = 100:8, 60 °C, 7.5 h, conversion = 93%; [LA] = 0.5 M, [LA]:[Cat] = 100:8, 60 °C, 3.5 h, conversion = 98%). The density functional theory calculation results revealed that CL interacted with the ligand through weak hydrogen bonds, and then approached the Ti center. After being attacked by isopropyl oxide, the carbonyl group of CL bonded to the Ti center. After the rearrangement and ring opening of CL ring, CL was converted to poly-ε-caprolactone.

Original languageEnglish
Article number122860
JournalPolymer
Volume204
DOIs
StatePublished - 9 Sep 2020

Keywords

  • L-lactide
  • Ring-opening polymerization
  • Titanium complex
  • ε-Caprolactone

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