氢键结合的偶氮聚合物配合物光取向的分子水平研究,Macromolecules

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氢键结合的偶氮聚合物配合物光取向的分子水平研究
Macromolecules ( IF 5.1 ) Pub Date : 2018-01-25 00:00:00 , DOI: 10.1021/acs.macromol.7b02534
Xiaoxiao Wang ₁ , Jaana Vapaavuori ₁ , C. Geraldine Bazuin ₁ , Christian Pellerin ₁

Affiliation

为了针对诸如可重写波导和全息数据存储之类的应用优化含偶氮苯的材料，必须了解偶氮苯结构对材料光响应的影响。超分子材料（其中复合的光活性偶氮苯控制了被动聚合物的运动或其他性能）对于研究特定化学修饰的影响而言非常方便。在这里，我们使用偏振调制红外结构吸收光谱（PM-IRSAS）研究以聚（4-乙烯基吡啶）（P4VP）为模型聚合物的氢键合超分子偶氮苯配合物。我们表明将尾基从氢（A _H）更改为氰基（A _CN）引起生色团更大的角度重新分布，并明显引起P4VP吡啶环取向。增加络合度会降低A _H和A _CN的饱和取向，而对于P4VP / A _CN它增加了吡啶的取向以及两种组分的取向稳定性。这些结果解释了先前对于这些络合物观察到的相反的光诱导双折射行为，并将偶氮-偶氮分子间的相互作用确定为主要原因。据我们所知，这是首次对偶氮苯对超分子偶氮聚合物配合物的光取向做出相反贡献的分子级光谱分析，也是关于小分子变化对偶氮染料转移光致取向能力的巨大影响的首次报道。制成光钝性聚合物。

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Molecular-Level Study of Photoorientation in Hydrogen-Bonded Azopolymer Complexes

To optimize azobenzene-containing materials for applications such as rewritable waveguides and holographic data storage, it is imperative to understand the effect of the azobenzene structure on the photoresponse of the material. Supramolecular materials, in which a complexed photoactive azobenzene controls the motion or other properties of a passive polymer, are uniquely convenient for studying the impact of specific chemical modifications. Here, we use polarization modulation infrared structural absorbance spectroscopy (PM-IRSAS) to study hydrogen-bonded supramolecular azobenzene complexes using poly(4-vinylpyridine) (P4VP) as a model polymer. We show that changing the tail group from hydrogen (A_H) to cyano (A_CN) induces greater angular redistribution of the chromophores and, remarkably, provokes P4VP pyridine ring orientation. Increasing the degree of complexation decreases the saturated orientation of both A_H and A_CN, whereas for P4VP/A_CN it increases the pyridine orientation as well as the orientation stability of both components. These results explain the contrasting photoinduced birefringence behavior previously observed for these complexes and identify azo–azo intermolecular interactions as the main reason. To our knowledge, this is the first molecular-level spectroscopic analysis of the contrasting contributions of azobenzenes to the photoorientation of supramolecular azopolymer complexes and the first report of the large impact of small molecular changes on the capacity of azo dyes to transfer light-induced orientation to a photopassive polymer.

更新日期：2018-01-25

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