Variable-Temperature Scattering and Spectroscopy Characterizations for Temperature-Dependent Solution Assembly of PffBT4T-Based Conjugated Polymers
Variable-Temperature Scattering and Spectroscopy Characterizations for Temperature-Dependent Solution Assembly of PffBT4T-Based Conjugated Polymers
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DOI：
10.1021/acsapm.1c01511
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发表时间：
2022-05-13
影响因子：
5
通讯作者：
Gu, Xiaodan
中科院分区：
文献类型：
--
作者：
Cao, Zhiqiang;Ma, Guorong;Gu, Xiaodan
用于浇铸薄膜的共轭聚合物（CP）的溶液结构对于定制薄膜形态从而器件性能至关重要。在这里，我们使用多峰变温散射和光谱工具来完全量化聚[（5，6-二氟-2，1，3-苯并噻二唑-4，7-二基）-alt-（3，3？二烷基-2，2 ';5 '，2“; 5”，2？- quatterthiophen-5，5？- diyl）]（PffBT 4 T）聚合物在不同的组装温度下具有不同的侧链长度。使用紫外可见光谱（UV-vis）、核磁共振（NMR）光谱、动态光散射（DLS）和小角中子散射（SANS）发现PffBT 4 T基CP的构象和聚集行为对温度和侧链长度非常敏感。我们发现，随着侧链长度从2-辛基十二烷基（C8 C12）到2-壬基十三烷基（C9 C13）的略微增加，基于PffBT 4 T的CP显示出聚集到溶解的链转变温度（10 ° C）、聚集度、聚集焓变和溶液中聚集体的尺寸的显著降低。在室温下，PffBT 4 T聚合物强烈聚集形成织物结构，膜厚度为几纳米厚和数百纳米长，如通过原子力显微镜（AFM）、透射电子显微镜（TEM）和动态光散射（DLS）探测的。根据温度依赖性SANS测量，在高于聚集到溶解链转变温度的升高的温度下，PffBT 4 T完全溶解并采用半柔性卷曲构象，其中PffBT 4 T-C8 C12的持续长度为3.1 nm，PffBT 4 T-C9 C13的持续长度略微增加为3.4 nm。与PffBT 4 T-C8 C12相比，PffBT 4 T-C9 C13的较长侧链也导致较小的聚集焓增益。本工作提供了一个解决方案的结构操纵策略的CP，从而将启发分子设计和处理协议的CP向更高性能的电子器件。
The solution structure of conjugated polymers (CPs) from which the films are cast is critical for tailoring the thin-film morphology thus device performance. Here, we used multimodal variable-temperature scattering and spectroscopy tools to fully quantify the solution assembly of poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3???-dialkyl-2,2 ';5 ',2 '';5 '',2???-quaterthiophen-5,5???-diyl)] (PffBT4T) polymers with varying side-chain lengths at different assembly temperatures. The conformational and aggregation behaviors for PffBT4T-based CPs were found to be very sensitive to both temperature and side chain length using ultraviolet-visible (UV-vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). We found that with slightly increasing side chain length from 2-octyldodecyl (C8C12) to 2-nonyltridecyl (C9C13), PffBT4T-based CPs show a significant decrease in aggregation-to-dissolved chain transition temperature (10 degrees C), degree of aggregation, enthalpy change of aggregation, and size of the aggregates in solution. At room temperature, PffBT4T polymer strongly aggregated to form fabric structure with the film thickness of a few nanometers in thickness and hundreds of nanometers in length, as probed by atomic force microscopy (AFM), transmission electronic microscopy (TEM), and dynamic light scattering (DLS). At the elevated temperature above the aggregation-to-dissolved chain transition temperature, PffBT4T is fully dissolved and adopts a semiflexible coil conformation with the persistence length of 3.1 nm for PffBT4T-C8C12 and a slightly increased persistence length of 3.4 nm for PffBT4T-C9C13, according to temperature-dependent SANS measurements. Longer side chains of PffBT4T-C9C13 also lead to less aggregation enthalpy gain compared with PffBT4T-C8C12. This work provides a solution structure manipulating strategy of CPs and thus will inspire the molecular design and processing protocols of CPs toward higher performance electronic devices.