Organocatalytic Cationic Ring-Opening Polymerization of a Cyclic Hemiacetal Ester

Angelika E. Neitzel, Thomas J. Haversang, Marc A. Hillmyer

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

We report the bulk cationic ring-opening polymerization of renewably sourced 2-methyl-1,3-dioxan-4-one (MDO) to yield a polyester with hydrolytically and thermally sensitive linkages that facilitate degradation. Neat monomer was successfully polymerized using a variety of protic acids as catalysts. We discovered that, with these catalysts, the cationic polymerization of MDO proceeds via two distinct mechanistic routes, namely, the activated monomer (AM) and active chain-end (ACE) mechanisms. The kinetics of these competing mechanistic avenues were investigated by employing diphenylphosphoric acid (DPP) with or without an alcohol initiator. Without an exogenous initiator, the polymerization propagates via a dioxacarbenium ion that rapidly adds more MDO to produce high-molar-mass poly(2-methyl-1,3-dioxan-4-one) (PMDO). However, we found no clear relationship between [MDO]0/[protic acid]0 and resultant molar mass, suggesting that the ACE mechanism is not well-controlled. This conclusion was further supported by the production of cyclic PMDO arising from unimolecular backbiting reactions as the system approached equilibrium. With an exogenous alcohol initiator, the polymerization proceeds primarily via an AM mechanism and affords a mixture of linear PMDO and a small amount of macrocyclics derived from the competing ACE mechanism. Consistent with this interpretation of competing mechanisms, a linear relationship between theoretical and observed molar mass was observed when the initial ratio of monomer to added initiator was <80.

Original languageEnglish (US)
Pages (from-to)11747-11755
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Volume55
Issue number45
DOIs
StatePublished - 2016

Bibliographical note

Funding Information:
*Tel.: 612-625-7834. E-mail: hillmyer@umn.edu. Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Funding This work was supported by the Center for Sustainable Polymers at the University of Minnesota, a National Science Foundation supported Center for Chemical Innovation (No. CHE-1413862). Notes The authors declare no competing financial interest.

Fingerprint Dive into the research topics of 'Organocatalytic Cationic Ring-Opening Polymerization of a Cyclic Hemiacetal Ester'. Together they form a unique fingerprint.

Cite this