The striking similarities in response to shear flow of nematic semi‐flexible thermotropic liquid crystalline polymers (LCPs) is reported. Insights into their complex flow was gained by in‐situ polarized optical microscopy (POM) whereas spatial correlations below optical resolution were characterized by small‐angle light scattering (SALS). The LCPs contained mesogenic units separated by ten (10) alkyl spacers, the polyether TPB10 of = 17 kDa and the polyester PSHQ10 of = 53 kDa. The quiescent nematic phase consisted of microdomains randomly oriented, that is, polydomain texture. Shear stretched and aligned the μm‐sized domains. After cessation of shear the texture sprang back and relaxed, PSHQ10 produced banded texture, whereas TPB10 only produced a disordered texture. Strikingly, high shear rate induced monodomains. Upon shear cessation the monodomain in PSHQ10 slowly relaxed to a polydomain, whereas TPB10 maintained a defect free texture. Shear reversal induced crisscross structure in both LCPs and SALS showed asymmetric “butterfly” patterns revealing a tilted microstructure. Shear rheometry in the nematic phase revealed that: (i) PSHQ10 displayed a terminal and rubbery regime, indicating the existence of entanglements; (ii) TPB10 exhibited only a liquid‐like behavior where G″ ≫ G′. The rubbery modulus G_e of PSHQ10 was ca. five times higher in the isotropic than in the nematic phase indicating that a change of conformation is involved in the nematic‐to‐isotropic transition. This study has resulted in correlations between rheological properties and shear‐induced microstructure thus developing new insights into their underlying deformation mechanisms.

中文翻译：

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半柔性热致聚合物向列和各向同性相中的剪切诱导织构和粘弹性。流变光学研究

据报道，向列型半柔性热致液晶聚合物（LCPs）的剪切流具有惊人的相似性。通过原位偏振光学显微镜（POM）可以洞悉它们的复杂流动，而低于光学分辨率的空间相关性则以小角度光散射（SALS）为特征。LCP包含由十（10）个烷基间隔基分隔的介晶单元，聚醚TPB10为= 17 kDa，聚酯PSHQ10为= 53 kDa。静态向列相由随机取向的微区组成，即多畴纹理。剪切拉伸并对齐了微米大小的区域。停止剪切后，纹理回弹并放松，PSHQ10产生带状纹理，而TPB10仅产生混乱的纹理。令人惊讶的是，高剪切速率诱导了单畴。剪切停止后，PSHQ10中的单畴缓慢松弛至多畴，而TPB10保持无缺陷的质地。LCP和SALS中的剪切逆转诱导的交叉结构显示出不对称的“蝴蝶”图案，显示出倾斜的微观结构。向列相的剪切流变测定表明：（i）PSHQ10表现出末端和橡胶态，表明存在纠缠；（ii）TPB10仅表现出类似液体的行为，其中G” ≫  G'。PSHQ10的橡胶模量G _e为。各向同性比向列相高五倍，表明向列向各向同性转变涉及构象变化。这项研究导致流变性质与剪切诱导的微观结构之间存在相关性，从而对其潜在的变形机理有了新的认识。