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Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated.
Linear amphiphilic diblock and ternary triblock copolymers were synthesized by the RAFT method in two successive steps using a poly(ethylene oxide) (PEO) macrochain transfer agent, butyl or 2-ethylhexyl acrylate, and 1H, 1H, 2H, 2H-perfluorodecyl acrylate. The diblock and the triblock copolymers, which consist of a hydrophilic, a lipophilic, and a short fluorophilic block, self-assemble in water into spherical micellar aggregates. Imaging by cryogenic transmission electron microscopy (cryo-TEM) revealed that the micellar cores of the aggregates made from these "triphilic" copolymers can undergo local phase separation to form a unique ultrastructure. In these multicompartment micelles, it appears that extended nonspherical domains, presumably made of nanocrystallites of the fluorocarbon block, are embedded in the hydrocarbon matrix forming the spherical micellar core. This novel internal structure of a micellar core is attributed to the mutual incompatibility of the fluorocarbon and hydrocarbon side chains in combination with the tendency of the used fluorocarbon acrylate monomer to undergo side-chain crystallization.