Crystalline complex between poly(γ-methyl l-glutamate) and dimethyl phthalate |
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Authors: | Junji Watanabe Y Sasanuma A Endo I Uematsu |
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Affiliation: | Department of Polymer Chemistry, Tokyo Institute of Technology, Ookayama, Meguroku, Tokyo 152, Japan |
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Abstract: | The crystalline complex between poly(γ-methyl l-glutamate) (PMLG) and dimethyl phthalate (DMP) has been formed in films cast from a solution in dichloroethane. It has the stoichiometry of 1 mol of DMP to three or four residues of PMLG and shows two definite characteristics in X-ray diffraction patterns; one is the large hexagonal unit cell with the edge of around 28 Å and another the ‘extra’ 5.07 Å meridional reflection which can not be interpreted by a PMLG α-helical conformation. The structural examination for the films with various DMP contents is carried out by X-ray, viscoelastic, and d.s.c. measurements and the following structure is proposed for the crystalline complex. Four PMLG are associated to form a group which is hexagonally packed and DMP molecules, located in the gaps between groups, form a specific favourable helical structure along PMLG chains in which the van der Waals stacking of benzene rings of DMP is significant. |
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Keywords: | dimethyl phthalate crystalline complex X-ray measurement van der Waals stacking of benzene rings |
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