Abstract
We report here the Zn(II)-catalyzed convergence of two metastable and isostructural polyesters to an isomeric polymer having a hyperbranched architecture. Ring-opening transesterification polymerization (ROTEP) of 4-carbomethoxyvalerolactone (CMVL) under Brønsted catalysis is known to give the linear polyester PCMVL. We show here that this can be isomerized to the equilibrated (and highly branched) polyester EQ-PCMVL. Analysis of the fragments obtained from eliminative degradation of EQ-PCMVL were critical in the formulation of its structure. The isomerization of PCMVL to EQ-PCMVL is a direct consequence of the presence of the second ester functional group in the CMVL ester-lactone, a rarely studied class of monomer. Zn(II)-catalysis of the ROTEP of the isomeric β-lactone, 2-(2-carbomethoxyethyl)propiolactone (isoCMVL), as well as isomerization of the isostructural linear homopolymer derived from that isomeric monomer, led to the same EQ-PCMVL. These results suggest a new strategy for the introduction of branching into various polyesters.
Original language | English (US) |
---|---|
Pages (from-to) | 1144-1148 |
Number of pages | 5 |
Journal | ACS Macro Letters |
Volume | 7 |
Issue number | 10 |
DOIs | |
State | Published - Oct 16 2018 |
Bibliographical note
Funding Information:Financial support for this work was provided by the Center for Sustainable Polymers at the University of Minnesota, an NSF-supported Center for Chemical Innovation (CHE-1413862). Some of the NMR data were obtained with an instrument whose purchase was enabled by the NIH Shared Instrumentation Grant Program (S10OD011952).
Publisher Copyright:
Copyright © 2018 American Chemical Society.