Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
Langmuir. 2013 Feb 5;29(5):1333-9. doi: 10.1021/la304280h. Epub 2013 Jan 23.
The morphological stability of polymer films is critically important to their application as functional materials. The deformation of polymer surfaces on the nanoscale may be significantly influenced by geometrical confinement. Herein, we constructed a mechanically heterogeneous polymer surface by phase separation in a thin polymer film and investigated the deformation behavior of its nanostructure (∼30 nm thickness and ∼100 nm average diameter) with tapping-mode atomic force microscopy. By changing different scan parameters, we could induce deformation localized to the nanostructure in a controllable manner. A quantity called the deformation index is defined and shown to be correlated to energy dissipation by tip-sample interaction. We clarified that the plastic deformation of a polymer on the nanoscale is energy-dependent and is related to the glass-to-rubber transition. The mobility of polymer chains beneath the tapping tip is enhanced, and in the corresponding region a rubberlike deformation with the lateral motion of the tip is performed. The method we developed can provide insight into the geometrical confinement effects on polymer behavior.
聚合物薄膜的形态稳定性对其作为功能材料的应用至关重要。聚合物表面在纳米尺度上的变形可能会受到几何约束的显著影响。在此，我们通过在薄聚合物薄膜中进行相分离构建了力学异质聚合物表面，并通过敲击模式原子力显微镜研究了其纳米结构（约 30nm 厚度和平均直径约 100nm）的变形行为。通过改变不同的扫描参数，我们可以以可控的方式诱导纳米结构的局部变形。定义了一个称为变形指数的量，并表明它与针尖-样品相互作用的能量耗散有关。我们阐明了纳米尺度上聚合物的塑性变形是能量依赖性的，并且与玻璃态到橡胶态转变有关。在敲击针尖下方的聚合物链的迁移率增强，并且在相应的区域中，通过针尖的横向运动来实现橡胶状的变形。我们开发的方法可以深入了解几何约束对聚合物行为的影响。
