One-Step Synthesis of Sequence-Tailored Amphiphilic Block Copolymers at the Emulsion Interface

The synthesis of sequence-controlled block copolymers (BCPs) via one-step copolymerization has garnered significant interest, as it offers a highly accessible and reproducible route. Herein, we describe a one-step strategy utilizing ring-opening metathesis polymerization (ROMP) at the emulsion interface for synthesizing amphiphilic BCPs with tailored sequences. Briefly, two norbornenyl monomers with similar reactivities containing hydrophilic tertiary amino and hydrophobic group, respectively, were dissolved in a CH₂Cl₂/H₂O emulsion, and the copolymerization was initiated by Grubbs' third-generation catalyst (G3). The hydrophobic monomer and G3 were localized within CH₂Cl₂ droplets, whereas the tertiary amine-bearing norbornene was distributed in both aqueous and CH₂Cl₂ phases, a partitioning that could be tuned by hydrochloric acid (HCl). Leveraging the partitioning effect of CH₂Cl₂/H₂O emulsion, ROMP was initiated in CH₂Cl₂ droplet and then propagated at the CH₂Cl₂/H₂O interface, enabling the one-step formation of well-defined amphiphilic BCPs. Notably, the unit sequence could be precisely tuned by HCl concentration, which governs the distribution of tertiary amine-bearing norbornene between the two phases. After polymerization, these amphiphilic BCPs at the CH₂Cl₂/H₂O interface could further undergo emulsion-induced self-assembly to prepare functional hybrid nanomaterials. Overall, this work offers a straightforward and efficient one-step strategy for sequence-tailored amphiphilic BCPs and their derived nanostructures.