Affiliation:
1. State Key Laboratory of Applied Organic Chemistry (Lanzhou University) Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province College of Chemistry and Chemical Engineering Lanzhou University Lanzhou 730000 China
2. State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China
3. Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province College of Chemistry and Chemical Engineering China West Normal University Nanchong 637002 China
Abstract
AbstractTo synthesize high molecular weight poly(phenolic ester) via a living ring‐opening polymerization (ROP) of cyclic phenolic ester monomers remains a critical challenge due to serious transesterification and back‐biting reactions. Both phenolic ester bonds in monomer and polymer chains are highly active, and it is difficult so far to distinguish them. In this work, an unprecedented selectively bifunctional catalytic system of tetra‐n‐butylammonium chloride (TBACl) was discovered to mediate the syntheses of high molecular weight salicylic acid‐based copolyesters via a living ROP of salicylate cyclic esters (for poly(salicylic methyl glycolide) (PSMG), Mn=361.8 kg/mol, Ð<1.30). Compared to previous catalysis systems, the side reactions were suppressed remarkably in this catalysis system because phenolic ester bond in monomer can be selectively cleaved over that in polymer chains during ROP progress. Mechanistic studies reveal that the halide anion and alkyl‐quaternaryammonium cation work synergistically, where the alkyl‐quaternaryammonium cation moiety interacts with the carbonyl group of substrates via non‐classical hydrogen bonding. Moreover, these salicylic acid‐based copolyesters can be recycled to dimeric monomer under solution condition, and can be recycled to original monomeric monomers without catalyst under sublimation condition.
Funder
National Natural Science Foundation of China