Exposing polymers to high-pressure and supercritical CO2 is a useful approach in polymer processing. Consequently, the mechanisms of polymer-polymer interaction under such conditions are worthy of further investigation. Two-dimensional (2D) correlation analysis and 2D disrelation mapping were applied to datasets of PCL(Polycaprolactone)/PLA (Poly(lactic acid)) blend with or without high-pressure CO2 obtained by in situ ATR-FTIR spectroscopic imaging. The relatively weak dipole-dipole intermolecular interactions between polymer molecules were visualized through the disrelation maps for the first time. Because of the specially designed polymer interface, the interactions between the same type of polymer molecules and different types of polymer molecules were differentiated. Under exposure to high-pressure CO2, all three types of interactions: interaction between PCL molecules and PLA molecules, interaction between PCL molecules and interaction between PLA molecules become weaker than those in the polymer interface without high-pressure CO2. The resulting increase in the Flory interaction parameter is the main cause of phase separation in the PCL/PLA blend under high-pressure CO2. The findings from this study will be of benefit for polymer processing with high-pressure and supercritical CO2.

中文翻译：

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EXPRESS：使用二维相关分析和二维非相关映射研究高压 CO ₂下聚合物共混物中的分子间相互作用

将聚合物暴露于高压和超临界 CO2 中是聚合物加工中的一种有用方法。因此，在这种条件下聚合物-聚合物相互作用的机制值得进一步研究。二维 (2D) 相关分析和二维非相关映射应用于 PCL（聚己内酯）/PLA（聚（乳酸））混合的数据集，有或没有高压 CO2，通过原位 ATR-FTIR 光谱成像获得。聚合物分子之间相对较弱的偶极-偶极分子间相互作用首次通过非相关图可视化。由于特殊设计的聚合物界面，相同类型的聚合物分子和不同类型的聚合物分子之间的相互作用是有区别的。在暴露于高压 CO2 下，所有三种类型的相互作用：PCL 分子和 PLA 分子之间的相互作用，PCL 分子之间的相互作用和 PLA 分子之间的相互作用变得比没有高压 CO2 的聚合物界面中的相互作用弱。Flory 相互作用参数的增加是 PCL/PLA 混合物在高压 CO2 下发生相分离的主要原因。这项研究的结果将有利于使用高压和超临界 CO2 进行聚合物加工。