Hierarchically Ordered Structures of Rod-Rod Block Copolymers Containing Two Mesogen-Jacketed Liquid Crystalline Polymers
Hierarchically Ordered Structures of Rod-Rod Block Copolymers Containing Two Mesogen-Jacketed Liquid Crystalline Polymers
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含有两种介晶包覆液晶聚合物的棒-棒嵌段共聚物的分级有序结构
DOI：
10.1021/acs.macromol.9b01759
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发表时间：
--
期刊：
影响因子：
5.5
通讯作者：
Xing-He Fan
中科院分区：
文献类型：
--
作者：
Zhehao Tang;Ping-Ping Hou;Wei Zhang;Xiaolin Lyu;Zhihao Shen;Xing-He Fan
为了研究影响棒状嵌段共聚物分级有序结构的因素，以两种聚丙烯酸基夹套液晶聚合物PNb 12 POSS [具有侧链多面体低聚倍半硅氧烷（POSS）单元]和PNb 10 PP为原料，设计并通过开环易位聚合合成了一种侧链棒状液晶基元，其中S和P分别是指PNb12POSS和PNb10PP两个链段，而m分别是指PNb12POSS和PNb10PP聚合过程中单体与催化剂的比例。对SmPn样品的相结构和行为的研究表明，这两种链段的液晶和结晶结构与其均聚物相似。PNb10PP链段与棒状介晶有序堆积形成近晶A（SmA）相，PNb12POSS链段与POSS单元晶体形成六方柱状（Colh）相。PNb12POSS的体积分数（fPNb12POSS）对SmPn的微相分离起着重要的作用。随着fPNb12POSS的增加，两个块体之间的不对称性变得更加明显，导致更大的弯曲曲率，并且S10P30，S20P30和S30P30的微相分离结构从层状（LAM）转变为六方堆积圆柱体（HEX）。此外，S20 P30和S30 P30中的PNb12 POSS片段形成可以通过透射电子显微镜清楚地观察到的Colh相。然而，由于高分子量和刚性导致的聚合物链的缓慢动力学，具有最低fPNb 12 Poss值的样品S30 P120不能形成有序结构，而S80 P120仅形成尺寸为约40 nm的缺乏规则性的HEX结构。
In order to investigate the factors affecting the hierarchically ordered structures of the rod–rod block copolymers, SmPnbased 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, whereasmandnrefer to the ratios of monomer to catalyst during polymerization of PNb12POSS and PNb10PP, respectively. Investigation on the phase structures and behaviors of SmPnsamples 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 (Colh) phase with the crystal of POSS units. The volume fraction of PNb12POSS (fPNb12POSS) plays an important role on the microphase separation of SmPn. The asymmetry between the two blocks becomes more pronounced with increasingfPNb12POSS, 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 Colhphases 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 lowestfPNb12POSSvalue cannot form ordered structures, while S80P120 only forms a HEX structure lacking regularity with a size of ∼40 nm.