Efficient catalysts for ring-opening polymerization of ε-caprolactone and β-butyrolactone: Synthesis and characterization of zinc complexes based on benzotriazole phenoxide ligands

Yu En Tai, Chen Yu Li, Chia Her Lin, Yi Chang Liu, Bao Tsan Ko, Ya Sen Sun

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

A series of efficient zinc catalysts supported by sterically bulky benzotriazole phenoxide (BTP) ligands are synthesized and structurally characterized. The reactions of diethyl zinc (ZnEt2) with CMe2PhBTP-H, t-BuBTP-H, and TMClBTP-H yield monoadduct [(μ-BTP)ZnEt]2 (1-3), respectively. Bisadduct complex [(t-BuBTP)2Zn] (4) results from treatment of ZnEt 2 with t-BuBTP-H (2 equiv.) in toluene, but treatment of TMClBTP-H with ZnEt2 in the same stoichiometric proportion in Et2O produces five-coordinated monomeric complex [( TMClBTP)2Zn(Et2O)] (5). The molecular structures of compounds 1, 4, and 5 are characterized by X-ray crystal structure determinations. All complexes 1-5 are efficient catalysts for the ring-opening polymerization of ε-caprolactone (ε-CL) in the presence of 9-anthracenemethanol. Experimental results indicate that complex 3 exhibits the greatest activity with well-controlled character among these complexes. The polymerizations of ε-CL and β-butyrolactone catalyzed by 3 are demonstrated in a "living" character with narrow polydispersity indices (monomer-to-initiator ratio in the range of 25-200, PDIs ≤1.10). The character of 3 provides a way to synthesize as much as 16-fold polymer chains of poly(ε-CL) (PCL) with narrow PDI in the presence of a catalyst in a small proportion. The controlled fashion of complex 3 also enabled preparation of the PCL-b-poly(3-hydroxybutyrate) copolymer.

Original languageEnglish
Pages (from-to)4027-4036
Number of pages10
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume49
Issue number18
DOIs
StatePublished - 15 Sep 2011

Keywords

  • β-butyrolactone
  • ε-caprolactone
  • benzotriazole phenoxide
  • biodegradable
  • catalysts
  • living polymerization
  • polyesters
  • ring-opening polymerization
  • zinc

Fingerprint

Dive into the research topics of 'Efficient catalysts for ring-opening polymerization of ε-caprolactone and β-butyrolactone: Synthesis and characterization of zinc complexes based on benzotriazole phenoxide ligands'. Together they form a unique fingerprint.

Cite this