Creation of A Two-dimensional Mesoscopic Quasicrystal with Dodecagonal Symmetry from An ABC Star-shaped Terpolymer

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It is well-established that block copolymers with incompatible components form nanophase-separated structures in condensed system due to their self-assembling nature. Star-shaped terpolymers whose three polymer chains are branched at one junction point are known to construct anisotropic cylinder-like structures in bulk, since their junction points have to be aligned on one-dimensional lines. Bulk structures of two series of star-shaped terpolymers were studied in this work, i.e., I_<1.0>S_<1.0>P_x, I_<1.0>SyP_<2.0>(I:polyisoprene, S : polystyrene, P : poly (2-vinylpyridine), X, Y are variable parameters), Solvent-cast and annealed films were used as samples. Several periodic Archimedean tiling structures with regular polygons, (6.6.6), (4.8.8) and (4.6.12) were observed fro two series. A little more complex structure,(3.3.4.3.4)), was observed for the latter series and, furthermore, more complex tiling structure composed of triangles and squares has been observed with a light change of composition from the sample with(3.3.4.3.4). The diffraction pattern with dodecagonal symmetry was observed for the sample, though it did not have periodic unit cell, which is the evidence of the quasicrystal with dodecagonal symmetry. The size of the sides of polygons is about 50nm, which is hierarchically scaled-up size from calcogenide and dendron systems.