The diffusion behavior of a typical disperse dye, disperse red 9 (DR 9), in the polyethylene terephthalate (PET) film at different temperatures was investigated by attenuated total reflection–Fourier transform infrared spectroscopy and 2D correlation spectroscopy (2Dcos) analyses. According to the Fickian diffusion model, the calculated diffusion coefficients of DR 9 in the PET film at different temperatures were observed to increase with temperature, which might be attributed to the increased free volume and thermal motion in the PET matrix and the rapid movement of DR 9 molecules at higher temperatures. In-detail analysis of the diffusion spectra discerned various kinds of molecular interactions, that is, intramolecular hydrogen bonding interactions of DR 9 and dipole–dipole and π–π interactions between DR 9 and PET. Among these, the dipole–dipole interactions between C═O groups of DR 9 and PET occurred first and played a vital role during the diffusion process of DR 9, as deduced from the sequence order of group motions in 2Dcos analysis.

中文翻译：

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红外光谱视角下聚乙烯对苯二甲酸酯薄膜中分散染料的动态扩散

通过衰减全反射傅里叶变换红外光谱和2D相关光谱（2Dcos）分析，研究了典型的分散染料分散红9（DR 9）在不同温度下在聚对苯二甲酸乙二醇酯（PET）膜中的扩散行为。根据菲克扩散模型，观察到在不同温度下，PET薄膜中DR 9的计算扩散系数随温度而增加，这可能归因于PET基质中自由体积和热运动的增加以及DR的快速运动。在较高温度下为9个分子。扩散光谱的详细分析发现了各种分子相互作用，即DR 9和偶极–偶极子的分子内氢键相互作用以及DR 9和PET之间的π–π相互作用。在这些当中，