Sequence-Controlled Neutral-Ionic Multiblock-Like Copolymers through Switchable PIESA in a One-Pot Approach

Abstract

Control over the composition and sequence of synthetic copolymers represents one of the most challenging targets in modern polymer science, in particular, for the labor- and time-consuming preparation of copolymers bearing ionic moieties. Though so far primarily focused on the assembly of coacervate nanostructures, we leverage polymerization-induced electrostatic self-assembly (PIESA) to achieve control over the composition and sequence of neutral-ionic copolymers and create complex chain topologies from equimolar mixtures of neutral and ionic monomers in a direct, one-pot process in aqueous solution. We are making use of the selective recruitment of charged over neutral monomers on an oppositely charged template to modulate monomer reactivities in situ during a controlled radical polymerization by creating segregated reaction environments. Varying the charge density of the template simply through cycling between acidic and alkaline pH drives the preferential incorporation of ionic over charge-neutral monomers by switching the template ON and OFF. Fine-tuning the length and order of the switching cycles enables the on-demand programming of specific block sequences and compositions, and even unique, alternating multiblock-like structures become accessible in a straightforward, one-pot process. Our results demonstrate a novel concept in taking advantage of the selectivity and reversibility of supramolecular compartmentalization of (charged) macromolecular building blocks to control and modulate monomer reactivities and chain topologies.