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

众所周知，具有不相容组分的嵌段共聚物由于其自组装性质，在凝聚体系中形成纳米相分离的结构。星形三元共聚物的三条链在一个结合点上支化，由于它们的结合点必须在一维直线上对齐，所以它们可以大量地构建各向异性的圆柱状结构。本文研究了两个系列星形三元共聚物的本体结构，即I_&lt；1.0&gt；S_&lt；1.0&gt；P_x，I_&lt；1.0&gt；SYP_&lt；2.0&gt；(I：聚异戊二烯，S：聚苯乙烯，P：聚(2-乙烯基吡啶)，X，Y为可变参数)，以溶剂浇铸和退火膜为样品。在两个系列中观察到了几个具有规则多边形的周期阿基米德瓷砖结构，(6.6.6)，(4.8.8)和(4.6.12)。观察到后一系列样品的结构略复杂，(3.3.4.3.4)，此外，还观察到由三角形和正方形组成的更复杂的瓷砖结构，成分与(3.3.4.3.4)样品相比变化不大。样品虽然没有周期晶胞，但仍观察到具有十二次对称的衍射图，这是准晶具有十二次对称的证据。多边形边的大小约为50 nm，这是从钙化物和树枝状系统分级放大的大小。

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.