Stimuli‐Responsive Macromolecular Architecture by Butler Cyclopolymerizations: Synthesis and Applications

Abstract This article reviews the synthesis of polyzwitterions (PZs) (poly‐carboxybetaines, ‐phosphonobetaines, and ‐sulfobetaines) having multiple pH‐responsive centers. The synthesis follows the Butler cyclopolymerization protocol involving a multitude of diallylammonium salts and their copolymerization with SO 2 and maleic acid. The PZs have been transformed into cationic‐, anionic‐polyelectrolytes, and polyampholytes under the influence of pH. Particular attention is given to the application of these polymers as antiscalants, mild steel corrosion inhibitors, components in constructing Aqueous Two‐Phase Systems (ATPSs), and membrane modifiers. The ATPSs could be used to separate various biomolecules, including proteins. Many amphiphilic polymers incorporating a few mol % hydrophobic monomers have shown enhanced viscosities and could be suitable for applications in oil fields. The progress of applying Butler cyclopolymerization in reversible addition‐fragmentation chain transfer (RAFT) chemistry has been discussed. Future works are expected to focus on RAFT cyclopolymerization to construct block copolymers.