Poly[di(ethylene glycol) vinyl ether]-stabilized poly(vinyl acetate) nanoparticles with various morphologies via RAFT aqueous emulsion polymerization of vinyl acetate

Reversible addition fragmentation chain transfer (RAFT) aqueous emulsion polymerization of vinyl acetate (VAc) is performed using poly[di(ethylene glycol) vinyl ether] (PDEGV) macromolecular chain transfer agents (macro-CTAs) including RAFT end-unfunctionalized PDEGV (up to 32%). Emulsion polymerization directly induces PDEGV-b-PVAc diblock copolymer assemblies in water. This facile formulation enables the production of various particle morphologies, such as spheres, rods (ellipsoids), and vesicles, depending on the composition of the block copolymer. Many other examples of RAFT emulsion polymerization syntheses only result in the formation of kinetically trapped spheres, even when targeting highly asymmetric diblock compositions. However, despite being stabilized only by homopolymer PDEGV macro-CTAs, including PDEGV, PVAc-based nanoparticles with various morphologies can be obtained as PDEGV-b-PVAc assemblies. RAFT aqueous emulsion polymerization owes its success to recent RAFT polymerizations of hydroxy-functionalized vinyl ethers. We investigated the RAFT polymerization of DEGV, analyzed the kinetics of PDEGV-b-PVAc nanoparticle formation, and observed the morphology of resultant particles in detail. We also developed a phase diagram for this RAFT aqueous emulsion polymerization formulation that reliably predicts the precise block compositions associated with well-defined particle morphologies.