Kipnusu Wycliffe K, Elmahdy Mahdy M, Mapesa Emmanuel U, Zhang Jianqi, Böhlmann Winfried, Smilgies Detlef-M, Papadakis Christine M, Kremer Friedrich
†Institute of Experimental Physics I, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
‡Department of Physics, Mansoura University, Mansoura 35516, Egypt.
ACS Appl Mater Interfaces. 2015 Jun 17;7(23):12328-38. doi: 10.1021/am506848s. Epub 2015 Feb 9.
The impact of 1- and 2-dimensional (2D) confinement on the structure and dynamics of poly(styrene-b-1,4-isoprene) P(S-b-I) diblock copolymer is investigated by a combination of Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Grazing-Incidence Small-Angle X-ray Scattering (GISAXS), and Broadband Dielectric Spectroscopy (BDS). 1D confinement is achieved by spin coating the P(S-b-I) to form nanometric thin films on silicon substrates, while in the 2D confinement, the copolymer is infiltrated into cylindrical anodized aluminum oxide (AAO) nanopores. After dissolving the AAO matrix having mean pore diameter of 150 nm, the SEM images of the exposed P(S-b-I) show straight nanorods. For the thin films, GISAXS and AFM reveal hexagonally packed cylinders of PS in a PI matrix. Three dielectrically active relaxation modes assigned to the two segmental modes of the styrene and isoprene blocks and the normal mode of the latter are studied selectively by BDS. The dynamic glass transition, related to the segmental modes of the styrene and isoprene blocks, is independent of the dimensionality and the finite sizes (down to 18 nm) of confinement, but the normal mode is influenced by both factors with 2D geometrical constraints exerting greater impact. This reflects the considerable difference in the length scales on which the two kinds of fluctuations take place.
通过扫描电子显微镜（SEM）、原子力显微镜（AFM）、掠入射小角X射线散射（GISAXS）和宽带介电谱（BDS）相结合的方法，研究了一维（1D）和二维（2D）受限环境对聚（苯乙烯 - b - 1,4 - 异戊二烯）P（S - b - I）二嵌段共聚物结构和动力学的影响。通过旋涂P（S - b - I）在硅衬底上形成纳米薄膜来实现一维受限，而在二维受限中，共聚物被渗透到圆柱形阳极氧化铝（AAO）纳米孔中。溶解平均孔径为150 nm的AAO基质后，暴露的P（S - b - I）的SEM图像显示出笔直的纳米棒。对于薄膜，GISAXS和AFM揭示了PI基质中PS的六方堆积圆柱体。通过BDS选择性地研究了三种介电活性弛豫模式，它们分别对应于苯乙烯和异戊二烯嵌段的两种链段模式以及后者的正常模式。与苯乙烯和异戊二烯嵌段的链段模式相关的动态玻璃化转变与受限的维度和有限尺寸（低至18 nm）无关，但正常模式受这两个因素的影响，其中二维几何约束的影响更大。这反映了两种波动发生的长度尺度上的显著差异。
