| Project/Area Number |
16605007
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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 |
計算科学
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| Research Institution | Yamaguchi University |
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Principal Investigator |
YAMAMOTO Takashi Yamaguchi University, Faculty of Science, Professor, 理学部, 教授 (00127797)
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| Co-Investigator(Kenkyū-buntansha) |
URAKAMI Naohito Yamaguchi University, Faculty of Science, Lecturer, 理学部, 講師 (50314795)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | polymers / crystallization / helical polymers / molecular recognition / computational science / computer simulation / molecular dynamics simulation / Monte Carlo simulation / コンピュータ・シミュレーション / 分子動力学シミュレーション / 構造発現 / 螺旋高分子 / キラリティー |
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| Research Abstract |
The molecular mechanism of crystallization in helical polymers is a fascinating but very difficult subject of research. We have made efforts toward better understanding of the crystallization in helical polymers by use of molecular dynamics simulation. Straightforward approaches to the problem being quite difficult, we have adopted a different strategy of categorizing the helical polymers into two distinct types ; one type is a simple bare helix which is essentially made of backbone atomic groups only and has smoother molecular contours, and the other is a more general helix having large side groups that would considerably hamper molecular motion and crystallization. Both types of helical polymers were constructed by use of the united atom model, but they showed quite distinct crystallization behavior ; the crystallization of the former type polymer was rather fast, while that of the latter type polymer was extremely slow. We have found that the bare helix, when rapidly cooled in free
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3D-space, freezes into partially ordered state with limited intramolecular and intermolecular order, and that remarkable improvement of order and growth of ordered chain folded crystallite occur by very longtime annealing of the partially ordered state around the apparent freezing temperature. We have also studied crystallization of the bare helix upon a growth surface ; the crystallization in this case proceeded much faster through highly cooperative process of the intermolecular and the intramolecular degree of freedom. On the other hand, crystallization of the realistic model of isotactic polypropylene (iPP) having pendant methylene groups was found to be extremely sluggish. By restricting the spatial dimension of the system thereby fully disentangling the chain, we have observed the molecule of iPP crystallize very quickly onto the crystal substrate made of the same iPP chain. Quite remarkable was that the molecule of iPP strictly recognizes the helical sense of the substrate chain and efficiently selects its chirality during crystallization. Less
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