Jump to main content
Jump to site search

Issue 48, 2011
Previous Article Next Article

Size-dependent growth of polymorphs in nanopores and Ostwald's step rule of stages

Author affiliations

Abstract

More than 100 years after Ostwald postulated his step rule of stages, predictive understanding as to early crystallization stages of polymorphic materials is still premature. We studied crystallization of the polymorphic pharmaceutical acetaminophen in nanoporous glasses as a model for early stages of bulk crystallization since the surface energy significantly contributes to the total Gibbs free energy of nanosized crystals in both cases. Systematic studies of transitions between different polymorphs inside nanoporous glasses show that the thermodynamic stability of the polymorphs depends on the crystal size. Accordingly, the transient occurrence of different polymorphs during crystal growth in bulk systems can be related to surface energy contributions to the total Gibbs free energy of the developing crystals. In nanosized early-stage crystals with high surface-to-volume ratios other polymorphs may be stable than in large crystals with low surface-to-volume ratios. Improved control of the crystallization of polymorphic materials by imposing well-defined confinement is a promising strategy to tailor release of polymorphic drugs and to optimize optical, electronic, magnetic and ferroelectric properties of polymorphic materials.

Graphical abstract: Size-dependent growth of polymorphs in nanopores and Ostwald's step rule of stages

Back to tab navigation

Publication details

The article was received on 21 Aug 2011, accepted on 07 Oct 2011 and first published on 27 Oct 2011


Article type: Paper
DOI: 10.1039/C1CP22679G
Citation: Phys. Chem. Chem. Phys., 2011,13, 21367-21374
  •   Request permissions

    Size-dependent growth of polymorphs in nanopores and Ostwald's step rule of stages

    G. T. Rengarajan, D. Enke, M. Steinhart and M. Beiner, Phys. Chem. Chem. Phys., 2011, 13, 21367
    DOI: 10.1039/C1CP22679G

Search articles by author

Spotlight

Advertisements