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J Am Chem Soc. 2012 Apr 11;134(14):6354-64. doi: 10.1021/ja300257m. Epub 2012 Mar 27.

Twisted mannitol crystals establish homologous growth mechanisms for high-polymer and small-molecule ring-banded spherulites.

Author information

1
Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, USA. shtukenberg@mail.ru

Abstract

D-Mannitol belongs to a large and growing family of crystals with helical morphologies (Yu, L. J. Am. Chem. Soc.2003, 125, 6380). Two polymorphs of D-mannitol, α and δ, when grown in the presence of additives such as poly(vinylpyrrolidone) (PVP) or D-sorbitol, form ring-banded spherulites composed of handed helical fibrils, where the helix axes correspond to the radial growth directions. The two polymorphs form helices with opposite senses in the presence of PVP but the same sense in the presence of D-sorbitol. The characteristic dimensions of the fibrils, including thickness, aspect ratio, and pitch, were determined by scanning probe and electron microscopies. These values must form the basis of any theory that presupposes what forces give rise to crystal twisting, a problem that has been broached but unsettled in the literature of polymer crystallization. The interdependence of the rhythmic variations of both linear and circular birefringence, as determined by Mueller matrix microscopy, informs the cooperative organization of mannitol fibers. The microstructure of mannitol ring-banded spherulites compares favorably to that of high polymers and is evaluated within the context of current theories of crystal twisting.

PMID:
22413815
DOI:
10.1021/ja300257m

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