Crystal Polymorphism of Curdlan Propionate: 6-Fold versus 5-Fold Helices
| Autor: | Kazuyori Yukinaka, Masaki Takata, Hironori Marubayashi, Tadahisa Iwata, Yukiko Enomoto-Rogers, Takaaki Hikima |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
chemistry.chemical_classification
Materials science Polymers and Plastics Annealing (metallurgy) Hexagonal crystal system Organic Chemistry 02 engineering and technology Curdlan Crystal structure 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry Polymorphism (materials science) Helix Materials Chemistry Propionate 0210 nano-technology Fiber diffraction |
| Zdroj: | ACS Macro Lett.. 5:607-611 |
| Popis: | The molecular and crystal structures of curdlan propionate (CDPr) were examined by the X-ray fiber diffraction methods combined with energy calculations. CDPr forms two different crystal structures (CDPr forms I and II) depending on annealing conditions: solvent-annealing yields CDPr form I, whereas thermal-annealing gives CDPr form II. In CDPr form I, the 6/1 helix is packed in the hexagonal unit cell with a = b = 1.154 nm, and c (fiber axis) = 2.287 nm. In the case of CDPr form II, the 5/1 helix is packed in the pseudohexagonal cell with a = b = 1.175 nm, and c (fiber axis) = 1.859 nm. The crystal transition from CDPr forms I to II occurs by thermal-annealing at temperatures ≥ 160 °C. |
| Databáze: | OpenAIRE |
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