Li Bolin, Lu Xiaolin, Ma Yonghao, Han Xiaofeng, Chen Zhan
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, China.
Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
ACS Macro Lett. 2015 May 19;4(5):548-551. doi: 10.1021/acsmacrolett.5b00185. Epub 2015 Apr 23.
A new methodology was developed to probe glass transition temperatures (s) of polymer thin films supported on gold (Au) substrates and confined between two solid (silica and silver) surfaces based on the surface plasmon polariton (SFPP) signals generated by sum frequency generation (SFG) spectroscopy. The measured s for polymer (poly(methyl methacrylate), poly(benzyl methacrylate) and poly(ethyl methacrylate)) thin films supported on Au substrates showed similar thickness-dependent trend, that is, the decreased as the thin film thickness decreased due to the free surface effect. However, the measured of the (poly(methyl methacrylate)) thin films confined between two solid surfaces increased significantly with respect to the bulk value, indicating the strong interfacial effect when the free surface was replaced by a buried interface. This method to measure the can be applied to study different polymer thin films supported on metal surfaces or confined between two solid surfaces with different surface chemistries. More importantly, SFG has the unique selectivity and sensitivity to study surfaces and interfaces, providing the feasibility to develop SFG into a powerful tool to detect surface, interfacial, and bulk s of a polymer thin film simultaneously in the future.
基于和频产生（SFG）光谱产生的表面等离激元极化激元（SPP）信号，开发了一种新方法来探测支撑在金（Au）衬底上并限制在两个固体（二氧化硅和银）表面之间的聚合物薄膜的玻璃化转变温度。在金衬底上支撑的聚合物（聚甲基丙烯酸甲酯、聚甲基丙烯酸苄酯和聚甲基丙烯酸乙酯）薄膜的测量结果显示出类似的厚度依赖性趋势，即由于自由表面效应，随着薄膜厚度减小，玻璃化转变温度降低。然而，限制在两个固体表面之间的聚甲基丙烯酸甲酯薄膜的测量值相对于本体值显著增加，表明当自由表面被埋入界面取代时存在强烈的界面效应。这种测量玻璃化转变温度的方法可用于研究支撑在金属表面或限制在具有不同表面化学性质的两个固体表面之间的不同聚合物薄膜。更重要的是，SFG对研究表面和界面具有独特的选择性和灵敏度，为未来将SFG开发成一种能够同时检测聚合物薄膜的表面、界面和本体玻璃化转变温度的强大工具提供了可行性。
