Synthesis of Linear, Cyclic, Figure-Eight-Shaped,
and Tadpole-Shaped Amphiphilic Block Copolyethers via <i>t</i>‑Bu‑P<sub>4</sub>‑Catalyzed Ring-Opening Polymerization
of Hydrophilic and Hydrophobic Glycidyl Ethers
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Abstract
This paper describes the synthesis
of systematic sets of figure-eight-
and tadpole-shaped amphiphilic block copolyethers (BCPs) consisting
of poly(decyl glycidyl ether) and poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl
glycidyl ether], together with the corresponding cyclic counterparts,
via combination of the <i>t</i>-Bu-P<sub>4</sub>-catalyzed
ring-opening polymerization (ROP) and click cyclization. The clickable
linear BCP precursors, with precisely controlled azido and ethynyl
group placements as well as a fixed molecular weight and monomer composition
(degree of polymerization for each block was adjusted to be around
50), were prepared by the <i>t</i>-Bu-P<sub>4</sub>-catalyzed
ROP with the aid of functional initiators and terminators. The click
cyclization of the precursors under highly diluted conditions produced
a series of cyclic, figure-eight-, and tadpole-shaped BCPs with narrow
molecular weight distributions of less than 1.06. Preliminary studies
of the BCPs self-assembly in water revealed the significant variation
in their cloud points depending on the BCP architecture, though there
were small architectural effects on their critical micelle concentration
and morphology of the aggregates