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Zwitterionic Ring-Opening Polymerization of N-Substituted Eight-Membered Cyclic Carbonates to Generate Cyclic Poly(carbonate)s

Authors :
Robert M. Waymouth
Andrey E. Rudenko
Young A. Chang
Source :
ACS macro letters. 5(10)
Publication Year :
2022

Abstract

The zwitterionic ring-opening polymerization of N-functionalized eight-membered cyclic carbonates with N-heterocyclic carbenes (NHC) in the absence of alcohol initiators generates cyclic polycarbonates of Mn ∼ 30–100 kDa. The polymerization behavior of these eight-membered cyclic azacarbonates depends sensitively on the nature of the nitrogen substituent. The N-benzyl-substituted eight-membered cyclic carbonate (8CCBn) polymerizes readily with 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene to generate cyclic polycarbonates with molecular weights of Mn = 14 000 to 96 000 Da. In contrast, the N-phenyl-substituted cyclic carbonate (8CCPh) catalytically dimerizes in the presence of the NHC to afford the crystalline cyclic dimer. The zwitterionic ring-opening copolymerization of δ-valerolactone (VL) and the cyclic carbonates afford gradient cyclic copolymers. The cyclic topology of both the homopolymers and copolymers was supported by MALDI-TOF MS and intrinsic viscosity measurements. 13C NMR and differential ...

Details

ISSN :
21611653
Volume :
5
Issue :
10
Database :
OpenAIRE
Journal :
ACS macro letters
Accession number :
edsair.doi.dedup.....00d74e40a1c673248d282c34241254fd