Understanding the Effects of Confinement and Crystallinity on HJ-Coupling in Conjugated Polymers via Alignment and Isolation in an Oriented Mesoporous Silica Host
Understanding the Effects of Confinement and Crystallinity on HJ-Coupling in Conjugated Polymers via Alignment and Isolation in an Oriented Mesoporous Silica Host
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通过定向介孔二氧化硅基质中的排列和分离了解限制和结晶度对共轭聚合物中异质耦合的影响
DOI：
10.1021/acs.jpcc.1c05844
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Tolbert, Sarah H.
中科院分区：
文献类型：
--
作者：
Winchell, K. J.;Voss, Matthew G.;Schwartz, Benjamin J.;Tolbert, Sarah H.
虽然在共轭聚合物中激子空间相干性的性质中存在显著的兴趣，但是通常不可能控制聚合物链之间的H-或J-耦合的程度，因为聚合物在旋涂成膜时具有自然优选的形态。在这项工作中，我们探索了共轭聚合物链中激子空间相干性的本质，这些聚合物链已通过封装在宏观排列的介孔二氧化硅主体的通道中而被拉直。小尺寸的孔阻碍了聚合物微晶的形成，使我们能够控制聚合物链构象而不结晶。这为我们研究非结晶直链聚合物链上的H-和J-偶联提供了一种方法，这是传统的薄膜铸造方法无法做到的。我们特别制备了两组不同的主体/客体复合材料，使用P3 HT（聚（3-己基噻吩））和MEH-PPV（聚[2-甲氧基-5-（2-乙基己氧基）-1，4-亚苯基亚乙烯基]）链作为客体。然后，我们进行了一系列的偏振吸收和发射实验上的封装的聚合物链，这表明，复合材料样品中每个包含两个不同的聚合物群体：一个主要对齐人口的拉直聚合物链和各向同性人口的卷曲和一般孤立的聚合物链。对齐的人口是更有序的比各向同性人口的两种聚合物，P3 HT的效果是特别明显的。我们发现，相同类型的光谱变化时观察到的P3 HT结晶也存在于拉直的P3 HT链，P3 HT仍然可以表现出H-占主导地位的聚集，即使没有扩展的结晶度。相比之下，MEH-PPV表现出增强的J-字符时，聚合物主链对齐和拉直的孔，与激子相干的大小，这是大于在旋转浇铸聚合物薄膜中观察到的。因此，这项研究为骨架拉直对H型和J型共轭聚合物聚集行为的影响提供了更基本的了解。
Although there has been significant interest in the nature of exciton spatial coherence in conjugated polymers, it is usually not possible to control the extent of H- or J-coupling between polymer chains because the polymers have a naturally preferred morphology when spin-cast into films. In this work, we explore the nature of exciton spatial coherence in conjugated polymer chains that have been straightened by encapsulation in the channels of a macroscopically aligned mesoporous silica host. The small size of the pores hinders the formation of polymer crystallites, allowing us to control the polymer chain conformation without crystallinity. This provides a way for us to study the H- and J-coupling on straight polymer chains that are not crystalline, something that cannot be done with traditional film casting methods. We specifically prepare two different sets of host/guest composites using both P3HT (poly(3-hexylthiophene)) and MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) chains as the guests. We then perform a series of polarized absorption and emission experiments on the encapsulated polymer chains, which reveal that the composite samples each contain two distinct polymer populations: a predominantly aligned population of straightened polymer chains and an isotropic population of coiled and generally isolated polymer chains. The aligned population is more ordered than the isotropic population for both polymers, an effect that is particularly pronounced for P3HT. We find that the same types of spectral changes observed when P3HT crystallizes are also present in the straightened P3HT chains and that P3HT can still exhibit H-dominant aggregation, even without extended crystallinity. In contrast, MEH-PPV exhibits enhanced J-character when the polymer backbone is aligned and straightened by the pores, with an exciton coherence size that is larger than that observed in spin-cast polymer films. This study thus provides a more fundamental understanding of the effects of backbone straightening on the aggregation behavior of both H- and J-type conjugated polymers.
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DOI：
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发表时间：
1999
期刊：
影响因子：
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作者：
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DOI：
10.1021/acs.jpclett.9b02070
发表时间：
2019-08
期刊：
The journal of physical chemistry letters
影响因子：
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作者：
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通讯作者：
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DOI：
10.1063/1.4819906
发表时间：
2013-09
期刊：
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影响因子：
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通讯作者：
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