Nonspherical Nanoparticles with Controlled Morphologies via Seeded Surface-Initiated Single Electron Transfer Radical Polymerization in Soap-Free Emulsion

Abstract

This work reports a facile novel approach to prepare asymmetric poly(vinylidene fluoride)/polystyrene (PVDF/PS) composite latex particles with controllable morphologies using one-step soap-free seeded emulsion polymerization, i.e., surface-initiated single electron transfer radical polymerization (SET-RP) of styrene (St) at the surface of PVDF seed particles. It was observed that the morphology was influenced mainly by the St/PVDF feed ratio, the polymerization temperature, and the length of the catalyst Cu(0) wire (Φ 1.00 mm). When the feed ratio was St/PVDF = 5.0 g/1.0 g, snowman-like Janus particles were exclusively obtained. Raspberry-like and popcorn-like composite particles were observed at a higher reaction temperature or a shorter length of the catalyst wire. The reaction kinetics plots demonstrated some unique features. The formation of nonspherical composite nanoparticles can be ascribed to the surface nucleation of PS bulges following the SET-RP.

Self‐Assembled Colloidal Particle Clusters from In Situ Pickering‐Like Emulsion Polymerization via Single Electron Transfer Mechanism

“…If there is no t BA in the monomer feed, the PS domains in the Janus particles are not hydrophobic enough to induce the self‐assembly in the aqueous media. This is observed in our recent report . At a low t BA/St feed ratio (0.25 g/2.5 g), the aggregation strength of the monomer‐swollen P(St‐ co ‐ t BA) is so weak that only small clusters can form (see the tetrahedral particles in Figure A).…”

“…In our previous study, PVDF/PS composite latex particles with controllable morphologies were prepared using the same SET‐RP method and similar reaction conditions. Snowman‐like, raspberry‐like, and popcorn‐like particles were obtained as a result of St polymerization on the surface of PVDF seeds.…”

“…Recently, we reported facile and relatively large‐scale syntheses of poly(vinylidene fluoride) (PVDF)/polystyrene (PS) Janus and nonspherical particles using seeded emulsion single electron transfer radical polymerization (SET‐RP) . Compared to other living radical polymerization methods, such as atom transfer radical polymerization, the SET‐RP method presents advantages, e.g., mild reaction condition, colorless polymer product, and easy removal of copper catalyst after reaction .…”

A Surfactant-Free and Shape-Controlled Synthesis of Nonspherical Janus Particles with Thermally Tunable Amphiphilicity

“…In that event, the surface properties of nonspherical particles are not properly exhibited because of the presence of stabilizers. Although several recent papers have reported producing nonspherical Janus particles without using stabilizers/surfactants, it is still necessary to develop various approaches to directly generate Janus characteristics (e.g., amphiphilicity) without using stabilizers.…”

Generalized Approach for Fabricating Monodisperse Anisotropic Microparticles via Single-Hole Swelling PGMA Seed Particles

“…37,38 Among these methods, emulsion polymerization is the most common choice to control microstructures of particles. 39,40 For example, Yang et al 41 prepared popcorn-like, molecule-like, and mushroom-like particles on the basis of the polystyrene (PS) seed particles by altering the amount of swelling solvent and the type of cross-linker. (b) Raspberry-shaped particles are synthesized in situ via a one-step procedure in the presence of the seed (or core) particles and second (or corona) particles.…”