Ionic hydrogen bond donor organocatalyst for fast living ring-opening polymerization
| Autor: | Zhao Chengxu, Wang Huiying, Li Xiaopei, Saide Cui, Kai Guo, Zhi Xu, Jingjing Liu, Cheng Chen, Xin Wang, Zhenjiang Li |
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| Rok vydání: | 2016 |
| Předmět: |
Polymers and Plastics
010405 organic chemistry Hydrogen bond Organic Chemistry Ionic bonding Bioengineering 010402 general chemistry 01 natural sciences Biochemistry Ring-opening polymerization 0104 chemical sciences Catalysis chemistry.chemical_compound chemistry Polymerization Organocatalysis Polymer chemistry Trimethylene carbonate Bifunctional |
| Zdroj: | Polymer Chemistry. 7:339-349 |
| ISSN: | 1759-9962 1759-9954 |
| DOI: | 10.1039/c5py01315a |
| Popis: | H-bonding organocatalysis using (thio)urea and amine has been very successful. Ionic H-bonding catalysis, especially in polymerizations, has scarcely been explored. Here we disclose guanidinium hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-ium [(HppH2)+] as a representative ionic H-bond donor (IHBD), combined with tertiary amines as H-bond acceptors (HBA), promoted fast ring-opening polymerization (ROP) of L-lactide (LLA). The positively charged IHBD guanidinium exhibits exceptional activating ability towards monomer LLA. Its partnership with (−)-sparteine demonstrates excellent IHBD–HBA binary catalysis in the ROP of LLA, which featured conversions up to 97%, predicted molecular weights (from 2550 to 17 900 g mol−1), narrow dispersities (Đ ≤ 1.12), and short reaction times of 30 to 180 minutes. A bifunctional synergistic activation mechanism by (HppH2)+ and (−)-sparteine is proposed, and is supported by NMR measurements. The controlled/living nature of the ROP is confirmed by kinetics and chain extension experiments. 1H NMR, SEC, and MALDI-ToF MS analyses strongly indicate that the obtained poly(L-lactide)s were exactly the designated ones. The successful synthesis of well-defined poly(trimethylene carbonate)-block-poly(L-lactide) verifies that the catalytic ROPs were of a controlled/living nature, and suggests that the IHBD–HBA binary catalysis system is generally applicable. |
| Databáze: | OpenAIRE |
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