Depth-Resolved Strucutre Analysis of Cylindrical Microdomain in Block Copolymer Thin Film by Grazing-Incidnece Small-Angle X-ray Scattering Utilizing Low-Energy X-rays
Depth-Resolved Strucutre Analysis of Cylindrical Microdomain in Block Copolymer Thin Film by Grazing-Incidnece Small-Angle X-ray Scattering Utilizing Low-Energy X-rays
复制标题
利用低能 X 射线掠入射小角 X 射线散射对嵌段共聚物薄膜中的圆柱形微区进行深度分辨结构分析
DOI：
10.1021/acs.macromol.5b01883
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发表时间：
2015
期刊：
影响因子：
5.5
通讯作者：
and Katsuhiro Yamamoto
中科院分区：
文献类型：
--
作者：
Itsuki Saito;Tsukasa Miyazaki;and Katsuhiro Yamamoto
采用掠入射小角X射线散射（GISAXS）技术，利用低能X射线（“柔和”X射线）对聚苯乙烯-b-聚（2-乙烯基吡啶）（S2 VP）薄膜（420 nm厚）进行了深度分辨结构分析。与利用硬X射线的技术相反，预计软X射线的穿透深度在聚合物表面的全反射的临界角周围逐渐变化。在本研究中，选择2.4 keV的X射线能量来控制穿透深度，实现深度敏感的GISAXS测量。薄膜中退火S2 VP的微相分离结构被证实是平行于衬底表面排列的六边形填充圆柱体（HEX）。当入射角接近临界角时，观察到布拉格斑在qz方向上显著伸长。（11）HEX衍射斑的实验半高宽（fwhm）值使用考虑X射线强度衰减衰减的劳厄函数估计的理论fwhm值来解释。通过改变入射角控制了穿透深度，深度分辨结构分析表明，六方晶格沿深度方向沿着发生形变，形变向表面逐渐松弛。所观察到的弛豫行为与表面附近的聚合物链的更高的流动性有关。
Depth-resolved structure analysis of a polystyrene-b-poly(2-vinylpyridine) (S2VP) thin film (420 nm thick) was achieved by grazing-incidence small-angle X-ray scattering (GISAXS) utilizing low-energy X-rays (“tender” X-rays). In contrast to techniques utilizing hard X-rays, a gradual change of the penetration depth of soft X-rays around the critical angle of total reflection of a polymer surface is anticipated. In this research, X-ray energy of 2.4 keV was chosen to control the penetration depth and achieve depth-sensitive GISAXS measurement. Microphase-separated structure of the annealed S2VP in the thin film was confirmed to be hexagonally packed cylinders (HEX) aligned parallel to the substrate surface. Significant elongation of the Bragg spots in theqzdirection was observed for an incidence angle close to the critical angle. The experimental full width at half-maximum (fwhm) values of the (11) HEX diffraction spot was interpreted using the theoretical fwhm values estimated using the Laue function considering an attenuation decay of X-ray intensity. The penetration depth was controlled by changing the incident angle, and depth-resolved structure analysis revealed that the hexagonal lattice deformed along the depth direction with the deformation gradually relaxed toward the surface. The observed relaxation behavior is related to the higher mobility of polymer chains near the surface.