Polymorphism of a long-chain cycloparaffin (CH2)120

Autor: Masaki Tsuji, Ken-ichi Katayama, Akiyoshi Kawaguchi, Kyo Jin Ihn
Rok vydání: 1992
Předmět:
Zdroj: Microscopy Research and Technique. 20:205-216
ISSN: 1097-0029
1059-910X
DOI: 10.1002/jemt.1070200208
Popis: The polymorphism of a long-chain cycloparaffin (CH2)120 and chain packing in its crystals were discussed on the basis of some results obtained mainly by transmission electron microscopy. Monoclinic and orthorhombic single crystals of (CH2)120 were isothermally grown together from a dilute solution in p-xylene. Lozenge-shaped orthorhombic single crystals were more frequently observed than lath-shaped monoclinic ones. The basal surfaces of orthorhombic and monoclinic single crystal platelets wore decorated with vapor-deposited polyethylene [PE]. Orthorhombic single crystals of (CH2)120 with the (110) twin boundary and monoclinic ones with the (100) twin boundary were also observed. Rod-like edge-on crystals of (CH2)120 were grown from a dilute p-xylene solution onto the (001) surface of alkali halides. The crystal system of the (CH2)120 edge-on crystals depended on the kind of substrate. The monoclinic crystal was grown on NaCl, the orthorhombic one on KBr and KC1. The monoclinic form of (CH2)120 edge-on crystal was transformed to the orthorhombic one by annealing on NaCl. In both monoclinic and orthorhombic edge-on crystals, the molecular plane determined by two zigzag stems in a molecule of (CH2)120 was parallel to the substrate surface and the molecular axis (crystallographic c-axis) was perpendicular to the longer side of the rod-like edge-on crystals. The sub-cell dimensions of the stem chains in both forms of (CH2)120 crystals were very similar to those of monoclinic and crthorhombic PE crystals, respectively.
Databáze: OpenAIRE
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