Direct determination of the π-helix structure and helix transition behavior of poly(β-phenethyl l-aspartate) via synchrotron X-ray diffraction |
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Authors: | Hidemine Furuya Toshinari Yanagihara Yuki Orito Hiroyasu Masunaga |
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Institution: | 1. School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan;2. JASRI/Spring-8, Sayo, Japan |
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Abstract: | The helix-sense inversions of poly(β-phenethyl l -aspartate) (2P) and diblock copolymers (2P-3P), with 2P and poly(β-phenylpropyl l -aspartate) (3P) blocks, were studied in their solid states using synchrotron wide-angle X-ray diffraction and small-angle X-ray scattering. The characteristic parameters of the π-helix structure of 2P were directly determined in situ after the helix transition at a high temperature. In the 2P-3P block copolymers, the main chains of the 3P blocks initially convert from right- to left-handed α-helices, and then the 2P blocks convert irreversibly from right-handed α-helices to left-handed π-helices. The chemical structures of the side chains of poly(l -aspartic acid ester)s significantly affect their helix transition behaviors. |
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Keywords: | helix structure helix–helix transition poly(β-phenethyl l-aspartate) synchrotron X-ray diffraction |
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