Phosphazene-catalyzed oxa-Michael addition click polymerization

Abstract

This paper reports a new type of click chemistry via a phosphazene bases-catalyzed oxa-Michael addition of an alcohol to an acrylate.

Step-Growth Polymerisation of Alkyl Acrylates via Concomitant Oxa-Michael and Transesterification Reactions

“…Again, DBU performed better than DMAP ( Table 2, to 2400 Da. [4][5][6][7][8][9] Thus, it can be assumed that by tuning the reaction conditions or changing the catalyst not only for the homopolymerisation of HEA but also for the herein presented auto-tandem polymerisation, higher molecular masses might be accessible. Mechanistically, the reaction is initiated either by deprotonation of the alcohol or by nucleophilic attack of the base/nucleophile on the Michael acceptor in a 1,4-or 1,2-fashion, generating a strongly basic zwitterion, which can subsequently deprotonate an alcohol.…”

Step-growth polymerisation of alkyl acrylates via concomitant oxa-Michael and transesterification reactions

“…8 Moreover, diacrylates and diols have been employed to synthesize poly(ester-ether)s catalysed by phosphazene base. 9,10 In all mentioned reactions, inert conditions were necessary and oligomers with M n s up to 2000 Da were obtained. Moreover, concomitant transesterification was identified as a side reaction leading to the reconstruction of the repeat units.…”

“…Moreover, concomitant transesterification was identified as a side reaction leading to the reconstruction of the repeat units. [4][5][6][7][8][9][10] Further step-growth polymerisations of acrylates comprising two different reaction mechanisms are a combined condensation and oxa-Michael addition reaction of acrylic acid and diols catalysed by a Brønsted acid and a tail-to-tail dimerisation combined with a transesterification of hydroxy-functionalized methacrylates activated by a NHC catalyst. 8,11 Further, a combination of an oxa-Michael addition of HEA with a ringopening polymerisation catalysed by phosphazene base has been disclosed.…”

pH and thermo responsive aliphatic tertiary amine chromophore hyperbranched poly(amino ether ester)s from oxa‐Michael addition polymerization

“…Compared with thiol‐Michael addition polymerization, oxa‐Michael polymerization has intrinsic advantages because of the larger number of readily available odorless and stable hydroxyl monomers. [ 41–43 ] Recently, we developed an efficient approach to synthesize hyperbranched poly(ester‐ether)s via oxa‐Michael addition polymerization from commercially available trifunctional hydroxyl and diacrylate monomers using phosphazene base ( t ‐BuP 2 ) as a catalyst. [ 44 ] In this work, we report a straightforward method for the preparation of pH and thermo responsive hyperbranched poly(amino ether ester)s via t ‐BuP 2 catalyzed oxa‐Michael addition polymerization of triethanolamine (TEOA) with EGDA at room temperature (Scheme 1).…”