Rod–rod block copolymers (BCPs) comprising different conjugated polymers are significant for meticulously tuning the two-phase transitions (microphase segregation and crystallization) and scrutinizing their structure–property relationships. However, in contrast to the extensively investigated conventional coil–coil BCPs, the investigation into the phase behaviors of rod–rod BCPs is limited theoretically and experimentally because of their semirigid characteristics. In this work, we synthesized a new family of poly(3-alkylthiophene)-block-poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (P3AT-b-PBTTT) with controlled molecular weights (MWs) and different alkyl side chains of either P3AT or PBTTT. We further examined the interplay between their cocrystallization (i.e., cocrystals of P3AT and PBTTT blocks) and microphase segregation (i.e., producing respective P3AT and PBTTT block crystal domains) by tuning the intrinsic (i.e., MWs and alkyl chains of P3AT and PBTTT) and extrinsic factors (i.e., thermal annealing and solvent) synergistically. Intriguingly, the larger MW of P3AT-b-PBTTT favors cocrystallization between P3AT and PBTTT blocks over their microphase segregation, which differs greatly from that of conventional coil–coil BCPs. Moreover, the closer interlayer lamellar spacing and side chain interdigitation between P3AT and PBTTT facilitated the formation of cocrystals. In contrast, thermal annealing at increased temperatures and slower solvent evaporation promoted microphase segregation between P3AT and PBTTT. The various crystalline structures of P3AT-b-PBTTT were closely connected to the device performance of field-effect transistors. This work highlights the robustness of molecular engineering and postprocessing collectively for tuning the cocrystallization and microphase segregation of all-conjugated BCPs.

中文翻译：

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研究用于有机场效应晶体管的精心设计的棒-棒聚（噻吩并）噻吩基嵌段共聚物中的共结晶和微相偏析


包含不同共轭聚合物的棒-棒嵌段共聚物（BCP）对于仔细调节两相转变（微相分离和结晶）和审查其结构-性能关系具有重要意义。然而，与广泛研究的传统线圈-线圈 BCP 相比，棒-棒 BCP 的相行为研究由于其半刚性特性而在理论和实验上受到限制。在这项工作中，我们合成了一个新的聚(3-烷基噻吩)-嵌段-聚(2,5-双(3-烷基噻吩-2-基)噻吩并[3,2-b]噻吩)家族(P3AT-b- PBTTT）具有受控分子量 (MW) 和 P3AT 或 PBTTT 的不同烷基侧链。我们通过调整本征（即 P3AT 和 PBTTT 的分子量和烷基链）和微相分离（即产生各自的 P3AT 和 PBTTT 块晶域）和外部因素（即热退火和溶剂）协同作用。有趣的是，较大的 P3AT-b-PBTTT MW 有利于 P3AT 和 PBTTT 块之间的共结晶而不是微相分离，这与传统的线圈-线圈 BCP 有很大不同。此外，P3AT和PBTTT之间更紧密的层间距和侧链交叉有利于共晶的形成。相反，升高温度的热退火和较慢的溶剂蒸发促进了 P3AT 和 PBTTT 之间的微相分离。 P3AT-b-PBTTT的各种晶体结构与场效应晶体管的器件性能密切相关。 这项工作强调了分子工程和后处理共同调节全共轭 BCP 的共结晶和微相分离的稳健性。