In order to investigate the factors affecting the hierarchically ordered structures of the rod–rod block copolymers, SmPn based on two polynorbornene-based mesogen-jacketed liquid crystalline (LC) polymers PNb12POSS [having side-chain polyhedral oligomeric silsesquioxane (POSS) units] and PNb10PP (with a side-chain calamitic mesogen) was designed and synthesized by ring-opening metathesis polymerization, in which S and P refer to the two segments PNb12POSS and PNb10PP, respectively, whereas m and n refer to the ratios of monomer to catalyst during polymerization of PNb12POSS and PNb10PP, respectively. Investigation on the phase structures and behaviors of SmPn samples indicates that the LC and crystalline structures of the two segments are similar to their homopolymers. The PNb10PP segment forms a smectic A (SmA) phase with the ordered packing of the rod-like mesogens, and the PNb12POSS segment forms a hexagonal columnar (Col_h) phase with the crystal of POSS units. The volume fraction of PNb12POSS (f_PNb12POSS) plays an important role on the microphase separation of SmPn. The asymmetry between the two blocks becomes more pronounced with increasing f_PNb12POSS, resulting in a larger bending curvature, and the microphase-separated structure changes from lamellar (LAM) to hexagonally packed cylinders (HEX) for S10P30, S20P30, and S30P30. Moreover, the PNb12POSS segments in S20P30 and S30P30 form Col_h phases that can be clearly observed by transmission electron microscopy. However, because of the slow kinetics of the polymer chains owing to the high molecular weight and rigidity, sample S30P120 having the lowest f_PNb12POSS value cannot form ordered structures, while S80P120 only forms a HEX structure lacking regularity with a size of ∼40 nm.

中文翻译：

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包含两种介晶夹层液晶聚合物的棒-杆嵌段共聚物的层级有序结构

为了研究影响杆-杆嵌段共聚物的层级有序结构的因素，S m P n基于两种聚降冰片烯基介晶夹层液晶（LC）聚合物PNb12POSS [具有侧链多面体低聚倍半硅氧烷（POSS）通过开环易位聚合反应设计和合成PNb10PP（带有侧链钙钛矿型液晶元），其中S和P分别指两个链段PNb12POSS和PNb10PP，而m和n指单体比例分别在PNb12POSS和PNb10PP的聚合过程中催化 S m P n的相结构和行为研究样品表明，这两个链段的LC和晶体结构与它们的均聚物相似。PNb10PP段与杆状介晶的有序堆积形成近晶A（SmA）相，而PNb12POSS段与POSS单元的晶体形成六角柱状（Col _h）相。PNb12POSS（f _PNb12POSS）的体积分数对S m P n的微相分离起着重要作用。随着f _PNb12POSS的增加，两个块之间的不对称性变得更加明显。导致更大的弯曲曲率，并且对于S10P30，S20P30和S30P30，微相分离的结构从层状（LAM）变为六角形填充圆柱体（HEX）。此外，S20P30和S30P30中的PNb12POSS片段形成Col _h相，可以通过透射电子显微镜清楚地观察到。但是，由于高分子量和高刚性导致聚合物链动力学变慢，具有最低f _PNb12POSS值的样品S30P120无法形成有序结构，而S80P120仅形成缺乏规则性的HEX结构，尺寸约为40 nm。