Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; Materials Characterization and Preparation Facility, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
J Colloid Interface Sci. 2017 Oct 15;504:758-764. doi: 10.1016/j.jcis.2017.05.120. Epub 2017 Jun 1.
The surface chain conformations of poly(methyl methacrylate) (PMMA) at different temperatures were extensively studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Similar to our previous experimental studies on polystyrene (PS) and poly(2, 3, 4, 5, 6-pentafluorostyrene) (5FPS), a transition temperature (T) could be identified through the principal component analysis (PCA) of the ToF-SIMS spectra obtained from the PMMA samples annealed at different temperatures. Interestingly, our results show that the T depended on molecular weight and was about 50-60˚C below the bulk glass transition temperature (T) and therefore could possibly be related to the surface glass transition temperature (T). These results were confirmed by contact angle measurements. ToF-SIMS results showed higher peak intensities of several low-mass oxygen-containing positive ions, hydrocarbon positive ions and OCH negative ion at higher temperatures, which can be interpreted by a higher surface concentration of methoxy groups at the surface.
采用飞行时间二次离子质谱（ToF-SIMS）技术广泛研究了不同温度下聚甲基丙烯酸甲酯（PMMA）的表面链构象。类似于我们之前对聚苯乙烯（PS）和聚（2,3,4,5,6-五氟苯乙烯）（5FPS）的实验研究，通过对不同温度退火的 PMMA 样品的 ToF-SIMS 谱图进行主成分分析（PCA），可以识别出转变温度（T）。有趣的是，我们的结果表明，T 取决于分子量，并且比本体玻璃化转变温度（T）低约 50-60°C，因此可能与表面玻璃化转变温度（T）有关。这些结果通过接触角测量得到了证实。ToF-SIMS 结果表明，在较高温度下，几种低分子量含氧正离子、烃类正离子和 OCH 负离子的峰强度较高，这可以通过表面甲氧基基团的表面浓度较高来解释。
