Chiral 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)-Catalyzed Stereoselective Ring-Opening Polymerization of rac -Lactide: High Reactivity for Isotactic Enriched Polylactides (PLAs)

• Published in: Polymers Vol. 12; no. 10; p. 2365
• Main Authors: Mahmood, Qaiser, Xu, Guangqiang, Zhou, Li, Guo, Xuanhua, Wang, Qinggang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.10.2020; MDPI
• Subjects: Amino acids; chiral TBD; high reactivity; Isotacticity; Molecular weight; Molecular weight distribution; NMR; Nuclear magnetic resonance; organocatalyst; Polylactic acid; Polymerization; Polymers; Ring opening polymerization; Room temperature; Stereoselectivity; chiral TBD; organocatalyst; high reactivity; stereoselectivity; ring-opening polymerization
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym12102365

Chiral 4,8-diphenyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (DiPh-TBD) was synthesized and applied to a ring-opening polymerization of -lactide ( -LA). The chiral DiPh-TBD promoted the synthesis of isotactic enriched polylactides (PLAs) with controlled molecular weight and narrow molecular weight distributions under mild, metal-free conditions. When the [ -LA]/[Cat.] ratio was 100/1, full monomer conversion was achieved within only 1 min and a moderate probability of 0.67 dyads ( ) was obtained at room temperature. A chain-end control mechanism (CEC) was found to be responsible for the isoselectivity based on the homodecoupled H NMR spectrum, the chiral HPLC measurement, and kinetic studies.