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Nano-Engineered Multiblock Copolymer Nanoparticles via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

Guimarães, Thiago R., Khan, Murtaza, Kuchel, Rhiannon P., Morrow, Isabel C., Minami, Hideto, Moad, Graeme, Perrier, Sébastien, Zetterlund, Per B.
Macromolecules 2019 v.52 no.8 pp. 2965-2974
acrylates, chemical bonding, coagulation, composite polymers, emulsions, equipment, flocculation, molecular weight, nanomedicine, nanoparticles, polymerization, solvents, styrene
Block copolymers composed of polymer segments of sufficiently high molecular weight such that microphase separation and self-assembly into complex nanostructured materials can occur provide a pathway to a myriad of nano-engineered materials with applications ranging from nanomedicine to materials science and microelectronics. In the present work, we have developed a methodology based on reversible addition–fragmentation chain transfer polymerization that allows the synthesis of multiblock copolymers based on sequential aqueous emulsion polymerization using the three most common industrially employed monomer families in emulsion polymerization systems: methacrylates, acrylates, and styrene. By exploiting the segregation effect (compartmentalization) resulting from polymerization within polymeric nanoparticles, a high molecular weight multiblock copolymer (up to 140,000 g·mol–¹) is obtained in a relative short time period of 3 h for each cycle of polymerization. The concept of nano-engineering of polymer nanoparticle morphology is demonstrated by exploiting the ability to covalently link numerous polymer blocks that are chemically incompatible, resulting in microphase separation and the formation of a well-defined multilayered structure within the nanoparticles. The method developed is environmentally friendly (use of water as solvent) and fulfills all requirements for scale up to an industrial process using existing industrial equipment such as no intermediate purification steps, relatively high solid content, good colloidal stability with no flocculation/coagulation, and near full monomer conversion.