Microphase-separated structures of a series of AB n block-graft copolymers were studied by transmission electron microscopy (TEM) coupled with small-angle X-ray scattering (SAXS). Five block-graft copolymers composed of the same polystyrene (S) backbone having polyisoprene (I) grafts with different chain lengths, wherein the numbers of grafts are almost constant (38 on average), were synthesized by living anionic polymerizations, resulting in coverage of the polystyrene composition range 0.32 ≤ φS ≤ 0.91. It was confirmed from the TEM observation that three low φS samples with φS of 0.32, 0.37, and 0.39 show complex spherical structures, while the sample with an φS of 0.57 reveals a hexagonal assembly of hexagonal rods of S in an I matrix, and the sample with φS of 0.91 exhibits inverse morphologies having rods of I in an S matrix. From detailed TEM and SAXS investigation combined with simulations, it has been found that the spherical structures formed from the samples with φS of 0.32 and 0.37 are both confirmed to have the structural feature of the Frank-Kasper A15 phase, which possesses the structural symmetry of the P m n space group.

Microphase‐separated structures of a series of AB6 block‐graft copolymers were studied by TEM and SAXS. Ten copolymers with the same polystyrene (S) backbone and six polyisoprene (I) grafts on the average but with different graft chain lengths were carefully synthesized by living anionic polymerization, covering the range 0.21 ≤ ϕS ≤ 0.90, where ϕS denotes polystyrene compositions. From TEM observation of the AB6 block‐graft copolymers, it turns out to be clear that they show four microphase‐separated structures, S‐spheres, S‐cylinders(S‐prisms), alternative lamellae, and I‐cylinders. Among them, for example, the samples with 0.54 ≤ ϕS ≤ 0.58 shows prism structures whose cross sections of the S domains are close to hexagons, not circles, due to packing frustration of grafts. Composition dependence of morphologies of the present AB6 block‐graft copolymers reveals their phase diagram is extremely asymmetric with respect to ϕS = 0.5. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 952–960

The first synthesis of dithieno-1,2-oxaborine derivatives was achieved via iodide-mediated or iodide-catalyzed demethylation of 3-methoxy-2,2′-bithiophene and subsequent C–H borylation. A wide variety of thiophene-fused oxaborines could be synthesized by the procedure.

Pure Mg, Mg 0.5 at Al, Mg 0.5 at Zn, Mg 0.5 at Y, Mg 0.9 at Y, and pure Zn single crystals were applied to indentation tests using a spherical indenter to allow experimental investigation the roles both slips and twinning induce on the formation of indentation. When indented on (0001), all single crystals displayed indentation of circular morphology without slip lines and twins. Mg and Mg alloys indentation sizes were found dependent on critical resolved shear stress CRSS for basal slip in (0001) indentations. Zn (0001) indentation size depends on CRSS for both basal and pyramidal slips. Conversely, when indented on (1010) and (1210), all single crystals had indentations elongated to [0001] with basal slip lines around indentations. Also, {1012} twins were observed in Mg 0.5 at Al and Mg 0.5 at Zn but were scarce in Mg Y. Pure Zn displayed second order pyramidal slips. Sizes of both (1010) and (1210) indentations were found dependent on CRSS for basal slips and for {1012} twins.

Indentation tests using a spherical indenter were applied to six hexagonal close-packed structure single crystals-pure Mg, Mg0.5 at%Al, Mg0.5 at%Zn, Mg0.5 at%Y, Mg0.9 at%Y, and pure Zn single crystals to investigate the roles both slips and twinning induce on the formation of indentation. When indented on (0001), all single crystals displayed circular morphology without slip lines or twins. Mg and Mg alloys' indentation sizes were found dependent on critical resolved shear stress (CRSS) for basal slip in (0001) indentations, while Zn (0001) indentation size depends on CRSS for both basal and second order pyramidal slips. Conversely, when indented on ð10 10Þ and ð1 210Þ, all single crystals displayed indentations elongated to [0001] surrounded by basal slip lines. Also, f10 12g twins were observed in Mg0.5 at%Al and Mg 0.5 at%Zn but were scarce in MgY. Pure Zn displayed second order pyramidal slips. Sizes of both ð10 10Þ and ð1 210Þ indentations were found dependent on CRSS for basal slips and for f10 12g twins.