Premium
Block Copolymerization of Lactide and an Epoxide Facilitated by a Redox Switchable Iron‐Based Catalyst
Author(s) -
Biernesser Ashley B.,
Delle Chiaie Kayla R.,
Curley Julia B.,
Byers Jeffery A.
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201511793
Subject(s) - cationic polymerization , polymerization , copolymer , cyclohexene oxide , epoxide , polymer chemistry , chemistry , monomer , lactide , redox , catalysis , oxidation state , organic chemistry , polymer
A cationic iron(III) complex was active for the polymerization of various epoxides, whereas the analogous neutral iron(II) complex was inactive. Cyclohexene oxide polymerization could be “switched off” upon in situ reduction of the iron(III) catalyst and “switched on” upon in situ oxidation, which is orthogonal to what was observed previously for lactide polymerization. Conducting copolymerization reactions in the presence of both monomers resulted in block copolymers whose identity can be controlled by the oxidation state of the catalyst: selective lactide polymerization was observed in the iron(II) oxidation state and selective epoxide polymerization was observed in the iron(III) oxidation state. Evidence for the formation of block copolymers was obtained from solubility differences, GPC, and DOSY‐NMR studies.