Lyotropic liquid crystalline (LC) phases offer a means of controlling molecular order and orientation in thin films of conjugated polymers. Surface energy, surface-induced ordering, and film thickness are additional factors determining the molecular order in thin films. Through solvent vapor annealing and in situ atomic force microscopy in the swollen state, we show that in ultrathin films of a poly(dithiazolyldiketopyrrolopyrrole-tetrafluorobenzene) (PTzDPPTzF4) alternating copolymer stacks of monomolecular-thick layers with a 2.1 nm step height form, which resemble a lyotropic smectic LC phase. Within the smectic layers, the polymer backbones are aligned parallel to the film plane, with edge-on oriented diketopyrrolopyrrole (DPP) cores. Thicker films resemble a semicrystalline morphology with lamellae consisting of blocks. Such lamellae are typical for polymers crystallizing via Strobl’s block-forming model. Our findings indicate that molecular order, molecular orientation, and the morphology of PTzDPPTzF4 copolymer films are tunable by LC order and by varying the film thickness according to the desired application of the particular organic electronic devices.

中文翻译：

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液晶有序度和膜厚决定了二酮吡咯并吡咯基共聚物的半结晶形态

溶致液晶 (LC) 相提供了一种控制共轭聚合物薄膜中分子顺序和取向的方法。表面能、表面诱导的有序性和薄膜厚度是决定薄膜分子有序性的附加因素。通过溶剂蒸汽退火和原位在膨胀状态下的原子力显微镜下，我们发现在聚（二噻唑二酮基吡咯并吡咯-四氟苯）（PTzDPPTzF4）交替共聚物堆叠的单分子厚层的超薄膜中，具有 2.1 nm 的台阶高度形式，类似于易溶近晶液晶相。在近晶层内，聚合物骨架平行于薄膜平面排列，具有边缘取向的二酮吡咯并吡咯 (DPP) 核心。较厚的薄膜类似于具有由块组成的薄片的半结晶形态。这种薄片对于通过 Strobl 的嵌段形成模型结晶的聚合物来说是典型的。我们的研究结果表明，分子顺序、分子取向、