Soft-materials such as block copolymers, surfactant and liquid crystals exhibit variety of ordered microstructures. Among them, the phase diagrams of diblock copolymers have been extensively investigated both experimentally and theoretically. Matsen and Shick[1] calculated the phase diagram of diblock copolymer melts by using self-consistent field theory (SCFT) and predicted that the phase diagram contains four types of structures: sphere packed in body-center-cubic, hexagonally-packed cylinders, lamellar and double-gyroid network. Khandpur et al.

A novel class of living radical polymerizations with germanium, tin, and phosphorus catalysts were developed. The polymerizations are based on a new reversible activation mechanism, Reversible chain Transfer (RT) catalysis. Low-polydispersity (M(w)/M(n) approximately 1.1-1.3) polystyrene, poly(methyl methacrylate), poly(glycidyl methacrylate), and poly(2-hydroxyethyl methacrylate) with predicted molecular weight were obtained with fairly high conversion in a fairly short time. The pseudo-first-order activation rate constant kact for the styrene/GeI4 (catalyst) system was large enough, even with a small amount of GeI4, explaining why the system provides low-polydispersity polymers from an early stage of polymerization. The retardation in the polymerization rate observed for the styrene/GeI4 system was kinetically proven to be mainly due to the cross-termination between the propagating radical with GeI3*. Attractive features of the germanium, tin, and phosphorus catalysts include their high reactivity hence small amounts (1-10 mM) being required under relatively mild conditions (at 60-100 degrees C), high solubility in organic media without ligands, insensitivity to air hence sample preparation being allowed in the air, and minor color and smell. The germanium and phosphorus catalysts may also be attractive for their low toxicity. The phosphorus catalysts may also be attractive for their low cost.

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The stability of the Fddd phase as an equilibrium phase in diblock copolymer melts was examined by using small-angle X-ray scattering and transmission electron microscopy. After 2 days of annealing at 150 °C where Fddd was found in a previous study (Takenaka et al. Macromolecules 2007, 40, 4399) for the poly(styrene-block-isoprene) (S−I), the Fddd structure still survived. The thermoreversibility in the order−order transitions (OOTs) between lamella (L) and Fddd and between gyroid (G) and Fddd was investigated. The long-time annealing at 150 °C induced the transformation from L and G to Fddd, indicating that Fddd is more stable than L and G at 150 °C. Fddd transformed into L and G, respectively, by annealing at 130 and 170 °C. These results supported that the OOTs between L and Fddd and between G and Fddd are thermoreversible. The stability of the Fddd structure after 2 days of annealing and the confirmation of the thermoreversibility in OOTs clarified that the Fddd phase exists as an equilibrium phase in S−I diblock copolymer melts.

We determined the phase boundary of the Fddd phase in the phase diagram of polystyreneblock-polyisoprene (SI) diblock copolymer by using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). We prepared eight SI diblock copolymers having different volume fractions of polyisoprene, f PI , in the range of 0.627 e f PI e 0.653 by living anionic polymerization. At the lowest f PI , 0.627, SI diblock copolymer showed only the disorder-lamellar (L) transition without any order-order transitions. SI diblock copolymer having the highest f PI , 0.653, exhibited disorder-gyroid (G)-L transitions with decreasing temperature but did not have the Fddd structure. Except for two samples described above, SI diblock copolymers exhibited disorder-G-Fddd-L transitions with decreasing temperature. It was found that the location of the Fddd region agreed with those obtained by using self-consistent-field theory calculation and Ginzburg-Landau theory.

Summary: Ge and Sn (non‐transition‐metal) catalyzed living radical polymerizations were developed. Low‐polydispersity (Mw/Mn ∼ 1.1–1.3) polystyrenes, poly(methyl methacrylate)s, poly(glycidyl methacrylate)s, and poly(2‐hydroxyethyl methacrylate) with predicted molecular weights were obtained with a fairly high conversion in a fairly short time. The pseudo‐first‐order activation rate constant kact for the styrene/GeI4 (catalyst) system was large enough, even with a small amount of GeI4, to explain why the system provides low‐polydispersity polymers from an early stage of polymerization. The retardation in the polymerization rate observed for the styrene/GeI4 system was kinetically proved to be mainly due to the cross‐termination between the propagating radical with GeI. Attractive features of the Ge and Sn catalysts include their high reactivity hence small amounts (1–5 mM) being required under a mild condition (at 60–80 °C), high solubility in organic media without ligands, insensitivity to air hence sample preparation being allowed in the air, and minor color and smell. The Ge catalysts may also be attractive for their low toxicity.

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