Janus particles by simplified RAFT-based emulsion polymerization process for polymer coating

Abstract

We describe a simplified method to synthesize film forming polymer Janus particles by phase separation during RAFT-based free radical emulsion polymerization. Fully crosslinked snowman- or football-shaped polystyrene Janus particles (PSJPs) were first produced in a one-step batch process using amphiphilic triblock macro-RAFT copolymers as stabilizers. Such particles were in turn employed as seeds in a continuous emulsion polymerization in which a monomer mixture of methyl methacrylate (MMA) and butyl acrylate (BA) (1/1 by weight) was constantly injected into the reaction in the presence of a water soluble initiator. The added monomers wetted seed particle surface and their polymerization led to formations of 93-nm film forming single- or two-headed Janus particles. The resulted latex was successfully used to disperse and encapsulate solid calcite extender. Graphical abstract

Tensile benefits of nanofibers in commercial paint films

“…39 The fine control of nanoparticle geometry via RAFT-PISA has also enabled the formation of Janus particles with film-forming lobes capable of encapsulating extenders and pigments in paint. 12,40 Polymeric nanofibers were shown to self-assemble into high aspect ratio, super paramagnetic self-assemblies in the presence of iron oxide nanoparticles. 41…”

“…8 The development of controlled radical polymerization techniques such as reversible addition-fragmentation chain transfer (RAFT) transformed the field of polymer science, enabling unprecedented control over macromolecular architecture. 9 In combination with RAFT, polymerization-induced self-assembly (PISA) 10 has been used to synthesize nano-assemblies of various shapes including micelles, vesicles, 11 snowman or football shaped particles, 12 capsules and fibers. 9,13 The great versatility of PISA is derived through selection of the macromolecular chain transfer agent, 14,15 with glass transition temperature (T g ) of the core-forming block, 16 water solubility of the core monomer, 17 and degree of protonation and solvophilicity of the macro-RAFT agent 18 all being factors that can influence assembly behaviour.…”

“…39 The fine control of nanoparticle geometry via RAFT-PISA has also enabled the formation of Janus particles with film-forming lobes capable of encapsulating extenders and pigments in paint. 12,40 Polymeric nanofibers were shown to self-assemble into high aspect ratio, super paramagnetic self-assemblies in the presence of iron oxide nanoparticles. 41 In this work we synthesize polymer nanofibers via industrially scalable RAFT-PISA processes and investigate how these nanofibers affect the tensile properties of commercially formulated pigmented paint systems.…”

Renewable and Functional Latexes Synthesized by Polymerization-Induced Self-Assembly for UV-Curable Films

“…The resulting particles are stabilized by a covalently bonded macro-RAFT agent. The RAFT-mediated PISA technique has also been employed to produce high solid content latexes, but its use for coatings has been reported only sparsely. − Other benefits of producing polymers under RAFT control are that the molecular weight can be controlled and backbiting reactions are suppressed, reducing the amount of branching. , These characteristics allow for the incorporation of biobased monomers with a more complex structure that adds functionality to the polymer backbone, limiting extensive cross-linking or side reactions.…”