2005 Fiscal Year Final Research Report Summary
Clarification of Order Structure Peculiar to the Near-surface Region of Crystalline Polymer Films and Dynamics on their Structural Formation
| Project/Area Number |
15550109
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Polymer chemistry
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| Research Institution | Japan Synchrotron Radiation Research Institute (JASRI/SPring-8) (2004-2005)
Kyushu University (2003) |
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Principal Investigator |
SASAKI Sono Japan Synchrotron Radiation Research Institute, Materials Structure Group I, Researcher, 利用研究促進部門・動的構造チーム, 副主幹研究員 (40304745)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Hirotsugu Kyusyu University, Institute for Materials Chemistry and Engineering, Professor, 先導物質化学研究所 融合材料部門, 教授 (50186201)
TANAKA Keiji Kyusyu University, Graduate School of Engineering, Associate Professor, 大学院・工学研究院, 助教授 (20325509)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Crystallization polymer films / SR-GIXD method / SR-GISAXS method / SPring-8, the large synchrotron radiation facility / Paracrystalline lattice distortion / Lamellar stacking structure / Higher-order structure / Annealing Effect |
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| Research Abstract |
We have successfully investigated chain and lamellar packing structures peculiar to crystalline polymers confined to narrow space, such as the surface and the thin film, by synchrotron grazing-incidence X-ray diffraction (SR-GIXD) and grazing-incidence small-angle X-ray scattering (SR-GISAXS) measurements. Thin films with a thickness of ca. 400 nm were prepared on silicon wafers from a p-xylene solution of high-density polyethylene (HDPE) by a dip-coating method. The dip-coated films and HDPE bulk samples were isothermally crystallized from the melt or annealed at various temperatures under nitrogen atmosphere.
In order to detect Bragg diffractions from the near-surface and bulk regions of the thin films, in-plane GIXD measurements were carried out at incident angles (α_i) of X-rays smaller and lager than the critical angle (α_c) at the BL13XU beamline of SPring-8 (Hyogo, Japan). It was revealed that the lattice constants a and b of orthorhombic unit cell in the near-surface region of t
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he thin film were smaller than those in the bulk region but larger than those of the bulk samples. This implied that the unit cell especially in the interfacial region between PE and silicon was distorted during sample preparation due to large mismatching between their thermal expansion coefficients. On the other hand, pracrystalline lattice analysis for the thin films indicated that long and short-range lattice distortion was larger in the near-surface region than in the bulk region. This might be related with the surface free energy of the film and/or releasing the latent heat from the surface.
SR-GISAXS measurements were carried out at α_i of X-rays smaller and lager than the α_c at the BL40B2 beamline of SPring-8. The 2D-GISAXS patterns from the films placed in a vacuum cell were detected at 300K with an imaging intensifier and a CCD detector or an imaging plate. Strong scattering in the in-plane direction near Yoneda peak were detected for all of the films. From the peak position of the scattering, it was found that the long period, the average distance between stacked crystalline lamellae, was ca.25-30 nm. From the GIXD data, it was implied that chains were relatively oriented parallel to the surface in the lamellae. Combination of GIXD and GISAXS data indicated that relatively edge-on oriented lamellae were stacked in the parallel direction to the surface. By annealing, partial melting and recrystallization might occur remarkably in the near-surface region. Less
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