2007 Fiscal Year Final Research Report Summary
Computer simulation of molecular recognition in self organization of helical polymers
| Project/Area Number |
18550196
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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/Textile materials
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| Research Institution | Yamaguchi University |
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Principal Investigator |
YAMAMOTO Takashi Yamaguchi University, Graduate School of Science and Engineering, Professor (00127797)
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| Co-Investigator(Kenkyū-buntansha) |
URAKAMI Naohito Yamaguchi University, Graduate School of Science and Engineering, Lecturer (50314795)
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| Project Period (FY) |
2006 – 2007
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| Keywords | polymers / crystallization / helical polymers / molecular recognition / self-organization / computer simulation / molecular dynamics simulation / Monte Carlo simulation |
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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 simulation methods. We have adopted a strategy of categorizing the helical polymers into two distinct types ; one 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.
(1) We already found that the bare helix rapidly crystallize in free 3D-space or on the crystalline substrate. However, the chirality recognotion was obscure in this rapidly crystallizing polymer. We have here investigated oligomeric helical polymers in order to establish the molecular mechanism of chirail crystallization in bare helical polymers combining both the MC and MD simulations. We have found that the initilal nucleation process doest not show marked chiraility selection, but at the late stage can be observe the growth of chirail crystals through stepwise ordering remniscent of the so called Ostwald Ripening Process.
(2) On the other hand, crystallization in realistic isotactic polypropylene model having large pendant groups was shown to be sluggish which renders the direct MD simulation in 3D-space extremely time consuming. We have here adopted a MC approach and the rigid chain model for the oligomeric iPP. We have found that the most stable a-form crystasl emerge through nucleation and growth by moderate cooling, while by very quick quench we have observed a disordered crystalline phase having a -form-like local chain packing but with overall chain packing of hexagonal symmetry, which conforms well to the so called smectic phase of iPP.
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