Abstract
The synthesis of well-defined block copolymers from a mixture of monomers without additional actions (“one-pot/one-step”) is an ideal and industrially valuable method. In addition, the presence of controlled alternating sequences in one or both blocks increases the structural diversity of polymeric materials, but, at the same time, the synthetic difficulty. Here we show that the “one-pot/one-step” ring-opening terpolymerization of a mixture of three monomers (N-sulfonyl aziridines; cyclic anhydrides and epoxides), with tert-butylimino-tris(dimethylamino)phosphorene (t-BuP1) as a catalyst, results in perfect diblock dialternating terpolymers having a sharp junction between the two blocks, with highly-controllable molecular weights and narrow molecular weight distributions (Ð < 1.08). The organocatalyst switches between two distinct polymerization cycles without any external stimulus, showing high monomer selectivity and kinetic control. The proposed mechanism is based on NMR, in-situ FTIR, SEC, MALDI-ToF, reactivity ratios, and kinetics studies.
Highlights
The synthesis of well-defined block copolymers from a mixture of monomers without additional actions (“one-pot/one-step”) is an ideal and industrially valuable method
We discovered that tert-butylimino-tris(dimethylamino)phosphorene (t-BuP1) catalyst shows high selectivity in monomers and kinetic control for two alternating copolymerization cycles without competitive side reactions leading to perfect diblock dialternating poly(ester amide)-b-polyester via a “one-pot/one-step” with a sharp boundary, controlled molecular weight and narrow molecular weight distribution
As a starting point for the current investigations, the terpolymerization of TAz, phthalic anhydride (PA), and propylene oxide (PO) with the initiator [BnN(H)Ts] without catalyst was performed at 100 °C in tetrahydrofuran (THF) or bulk
Summary
The synthesis of well-defined block copolymers from a mixture of monomers without additional actions (“one-pot/one-step”) is an ideal and industrially valuable method. We discovered that tert-butylimino-tris(dimethylamino)phosphorene (t-BuP1) catalyst shows high selectivity in monomers and kinetic control for two alternating copolymerization cycles without competitive side reactions leading to perfect diblock dialternating poly(ester amide)-b-polyester via a “one-pot/one-step” with a sharp boundary, controlled molecular weight and narrow molecular weight distribution. The size-exclusion chromatography (SEC, Supplementary Fig. 1) traces were shifted to high molecular weight, but maintained unimodal/narrow distributions (Ð < 1.07), supporting that ROCOP of TAz/PA is well controlled without any transesterification reaction.
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