Multiblock copolymer synthesis via aqueous RAFT polymerization-induced self-assembly (PISA)

Abstract

Reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) emulsion polymerization is used to prepare multiblock copolymers. Initially, well-defined polystyrene seed particles are synthesized with high livingness, followed by sequential seeded...

Electrochemically-Initiated RAFT Synthesis of Low Dispersity Multiblock Copolymers by Seeded Emulsion Polymerization

“…In parallel with these developments in eRAFT, significant achievements were being made with respect to using the “nanoreactor concept” and compartmentalization effects for multiblock copolymer synthesis and preparation of nanostructured particles by thermally initiated seeded emulsion polymerization. − These concepts encompass the idea that segregation of the polymerization locus into multiple particles, i.e., nanoreactors, conveys a range of benefits largely stemming from the kinetic enhancing effects of a reduced rate of termination, borne from the compartmentalization of propagating radicals. ,, Such conditions are ideal for multiblock copolymer syntheses, which have traditionally suffered from issues relating to low polymerization rates and intermediate purification. Subsequently, an uptick of advancements has been observed in this field; multiblock copolymers exhibiting high molecular weights, unconventional block orders, and notable architectures ,, have been synthesized to high conversion and low dispersity via sequential monomer addition.…”

“…The reason for that is currently unclear and further studies are necessary before progressing to the synthesis of methacrylate multiblock copolymers. We have previously synthesized methacrylate multiblocks with low molar mass dispersity by thermally initiated seeded RAFT emulsion polymerization at higher temperatures (80 °C). ,, …”

“…These promising results are attributed to the successful exploitation of the nanoreactor concept and compartmentalization effects. − As in conventionally initiated RAFT emulsion polymerization performed under otherwise similar conditions, these effects act to reduce the rate of bimolecular termination. In the case of eRAFT, the same effects are also expected to reduce the irreversible consumption of macroRAFT, and passivation of the working electrode.…”

“…We have previously synthesized methacrylate multiblocks with low molar mass dispersity by thermally initiated seeded RAFT emulsion polymerization at higher temperatures (80 °C). 12 , 13 , 21 …”

“…We observed a possibly similar phenomenon in multiblock synthesis (see Figure S9). However, substantially longer multiblocks have been synthesized by conventionally initiated seeded RAFT emulsion polymerization at a higher temperature (80 °C). ,, It is also possible that conducting the polymerization at ambient temperature exacerbates issues we have previously attributed to radical penetration . In experiments conducted at 80 °C, this phenomenon was found to particularly affect the synthesis of particles comprising high T g blocks (such as PSt) when prepared with polar initiators (such as KPS).…”