Understanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-ray Scattering
Understanding Solution State Conformation and Aggregate Structure of Conjugated Polymers via Small Angle X-ray Scattering
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DOI：
10.1021/acs.macromol.1c02449
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发表时间：
2022-06-14
期刊：
影响因子：
5.5
通讯作者：
Diao, Ying
中科院分区：
文献类型：
--
作者：
Kwok, Justin J.;Park, Kyung Sun;Diao, Ying
给体-受体（D-A）共轭聚合物是一类具有复杂聚集行为的高性能有机电子材料。了解共轭聚合物的溶液状态构象和聚集对于控制薄膜沉积过程中的形态和随后的电子性能至关重要。然而，一个精确的多尺度结构的溶液状态聚集体是缺乏的。在这里，我们提出了一个深入的小角X射线散射（SAXS）分析的溶液状态结构的异靛蓝-联噻吩为基础的D-A聚合物（PII-2 T）在氯苯和癸烷作为我们的主要系统。建模系统作为一个组合的分层纤维状聚集体与分散的聚合物混合，我们提取信息的构象和多尺度聚集，也澄清的物理起源经常观察到的功能，但未解决或误解的共轭聚合物的小角度散射模式。从SAXS中提取的D-A聚合物的持久长度与基于二面角势的理论模型吻合得很好。此外，我们表明，广泛的高Q结构因子峰散射曲线中看到的可以归因于层状堆积内发生的原纤维聚集体和低Q聚集体散射的聚合物分子量的强烈影响。总的来说，D-A聚合物的SAXS曲线通常表现出对纤维状聚集体和分散的聚合物链群体的共存的敏感依赖性。我们证实了我们的研究结果，从SAXS与电子显微镜的冻干样品的纤维状聚集体的直接成像。最后，我们证明了我们的方法的一般性，通过拟合的散射曲线的各种D-A聚合物的基础上噻吩并异靛蓝（PTII-2 T），二酮基吡咯并吡咯（DPP 2 T-TT，DPP-BTZ，PDPP 2FT-C-16），萘二酰亚胺（P（NDI 2 OD-T2）），和共轭嵌段共聚物P3 HT-b-DPPT-T。本文给出的结果建立了D-A聚合物溶液状态结构的图像，并提供了解释和分析其散射分布的一般方法。
Donor-acceptor (D-A) conjugated polymers are high-performance organic electronic materials that exhibit complex aggregation behavior. Understanding the solution state conformation and aggregation of conjugated polymers is crucial for controlling morphology during thin-film deposition and the subsequent electronic performance. However, a precise multiscale structure of solution state aggregates is lacking. Here, we present an in-depth small-angle X-ray scattering (SAXS) analysis of the solution state structure of an isoindigo-bithiophene-based D-A polymer (PII-2T) in chlorobenzene and decane as our primary system. Modeling the system as a combination of hierarchical fibrillar aggregates mixed with dispersed polymers, we extract information about conformation and multiscale aggregation and also clarify the physical origin of features often observed but unaddressed or misinterpreted in small-angle scattering patterns of conjugated polymers. The persistence length of the D-A polymer extracted from SAXS agrees well with a theoretical model based on the dihedral potentials. Additionally, we show that the broad high q structure factor peak seen in scattering profiles can be attributed to lamellar stacking occurring within the fibril aggregates and that the low q aggregate scattering is strongly influenced by the polymer molecular weight. Overall, the SAXS profiles of D-A polymers in general exhibit a sensitive dependence on the co-existence of fibrillar aggregate and dispersed polymer chain populations. We corroborate our findings from SAXS with electron microscopy of freeze-dried samples for direct imaging of fibrillar aggregates. Finally, we demonstrate the generality of our approach by fitting the scattering profiles of a variety of D-A polymers based on thieno-isoindigo (PTII-2T), diketopyrrolopyrrole (DPP2T-TT, DPP-BTZ, PDPP2FT-C-16), naphthalenediimide (P(NDI2OD-T2)), and a conjugated block copolymer P3HT-b-DPPT-T. The results presented here establish a picture of the D-A polymer solution state structure and provide a general method of interpreting and analyzing their scattering profiles.