Raspberry-like patchy particles achieved by decorating carboxylated polystyrene cores with snowman-like poly(vinylidene fluoride)/poly(4-vinylpyridiene) Janus particles

- PVDF/P4VP Janus particles were prepared via soap-free seeded emulsion polymerization.
- P(St-co-AA) core particles were synthesized by soap-free emulsion polymerization.
- RCPCs were obtained via hierarchical self-assembly of PVDF/P4VP Janus particles and P(St-co-AA) cores.

Nonspherical poly(vinylidene fluoride)/poly(4-vinyl pyridine) (PVDF/P4VP) composite particles were prepared via a facile one-step soap-free seeded emulsion polymerization. A moderate amount of ammonia solution was introduced into the polymerization system to make the composite latex particles uniform and stable, possibly due to the prevention of P4VP nucleation in the aqueous phase. Depending upon the stirring speed, the composite particles exhibited either the dumbbell-like shape (at a low speed) or the snowman-like shape (at a high speed). The size of the P4VP bulges in the composite particles could be easily adjusted by controlling the feed ratio of 4VP/PVDF. Utilizing the strong interactions between pyridine and carboxylic acid units, self-assembly of snowman-like PVDF/P4VP composite particles with carboxylated PS particles induced the formation of raspberry-like colloidal particle clusters (RCPCs) with PVDF bulges protruding outward. This study provides an alternative way to prepare hierarchical RCPCs.

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