Association behavior of different kind of block chains A and C in A-B-C triblock copolymer, and challenge to control the middle B block to form loop or bridge conformation

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Possibility to form comicelles with mixed cores comprising of different kind of block chains A and C in A-B-C triblock copolymers and to control the middle B block chain to take loop or bridge conformation has been studied by light scattering and linear and non-linear viscoelastic measurements. Poly (methyl methacrylate), poly (t-butyl acrylate), and polystyrene was used as each A, B, and C blocks, and 1-butanol was used as selective solvent for B block. Following results have been obtained.1) AB and BC diblock copolymer dilute solution forms micelles at room temperature. Near the critical micelle temperature, a huge aggregation was observed and anomalous micellization phenomenon was suggested.2) Semidilute solution of A-B-A triblock forms thermo-reversible physical gel, and its viscoelastic behavior was Maxwell-type with single relaxation time.3) Dilute solution of A-B-C triblock copolymer forms micelles with PS cores when cooled from 100℃. Further cooling induces that PMMA forms core with the already associated PS chains and the middle PtBuA takes loop conformation.4) Semidilute solution of A-B-C triblock copolymer forms physical gel below 50℃. Steady shear deformation induces re-construction of the network structure by the fraction-change of loop and bridge conformation for B chain. The network structure depends strongly on the process to make the gel.