The aggregation states of polymer chains at solid interfaces are strongly related to their adhesion properties. In this study, we focused on sum-frequency generation (SFG) vibrational spectroscopy, which offers the best depth resolution at the sub-nanometer level among available techniques, and explored its potential as an imaging method. A poly(methyl methacrylate) (PMMA) thin film with a line-and-space pattern was prepared on a quartz substrate. Imaging of the interfacial line-and-space structure in the film was successfully achieved based on SFG signals arising from ester methyl groups as well as carbonyl groups. Once SFG imaging was established, it was applied to blend films of polystyrene (PS) and PMMA with different compositions on the quartz substrate, enabling the direct and non-destructive observation of wetting layers and phase-separated structures buried at the substrate interface for the first time. The interfacial adhesion strength between the blend films and the quartz substrate, evaluated using the surface and interfacial cutting analysis system, showed a clear correlation with the interfacial structure of the blend. This study, which enables the analysis of the relationship between the local orientation of polymer chains at the interface and adhesion strength, is expected to contribute greatly to the design of next-generation adhesives and adhesion technologies.

中文翻译：

---

聚合物链界面局部构象对粘合强度的影响


固体界面上聚合物链的聚集状态与其粘附性能密切相关。在这项研究中，我们专注于和频发生（SFG）振动光谱，它在现有技术中提供了亚纳米级的最佳深度分辨率，并探索了其作为成像方法的潜力。在石英基板上制备具有线和空间图案的聚（甲基丙烯酸甲酯）（PMMA）薄膜。基于酯甲基和羰基产生的 SFG 信号，成功实现了薄膜中界面线和空间结构的成像。 SFG成像建立后，将其应用于石英基板上不同成分的聚苯乙烯（PS）和PMMA的混合薄膜，从而能够直接、无损地观察埋在基板界面处的润湿层和相分离结构，以实现第一次。使用表面和界面切割分析系统评估共混物薄膜和石英基底之间的界面粘合强度，显示出与共混物的界面结构明显的相关性。这项研究能够分析界面处聚合物链的局部取向与粘合强度之间的关系，预计将对下一代粘合剂和粘合技术的设计做出巨大贡献。