title: The Effect of Polymorphism on Surface Energetics of D-Mannitol Polymorphs.
abstract: The aim of this work was to assess the effect of different crystalline polymorphism on surface energetics of D-mannitol using finite dilution inverse gas chromatography (FD-IGC). Pure α, β and δ polymorphs were prepared via solution crystallisation and characterised by powder X-ray diffraction (P-XRD). The dispersive surface energies were found to range from 43 to 34 mJ/m2, 50 to 41 mJ/m2, and 48 to 38 mJ/m2,for α, β, and δ, respectively, for surface coverage ranging from 0.006 to 0.095. A deconvolution modelling approach was employed to establish their energy sites. The primary sites corresponded to maxima in the dispersive surface energy of 37.1 and 33.5; 43.3 and 39.5; and 38.6, 38.4 and 33.0; for α, β, and δ, respectively. This methodology was also extended to an α-β polymorph mixture to estimate the amount of the constituent α and β components present in the sample. The dispersive surface energies of the α-β mixture were found to be in the range of 48 to 37 mJ/m2with 40.0, 42.4, 38.4 and 33.1 mJ/m2sites. The deconvolution modelling method extracted the energy contribution of each of the polymorphs from data for the polymorphic mixture. The mixture was found to have a β-polymorph surface content of ∼19%. This work shows the influence of polymorphism on surface energetics and demonstrates that FD-IGC coupled with a simple modelling approach to be a powerful tool for assessing the specific nature of this energetic distribution including the quantification of polymorphic content on the surface.
authors.affiliation: Surfaces and Particle Engineering Laboratory, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Smith
authors.affiliation: Surfaces and Particle Engineering Laboratory, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
authors.forename: Umang V
authors.initials: UV
authors.lastname: Shah
authors.affiliation: Surfaces and Particle Engineering Laboratory, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
authors.forename: Jose V
authors.initials: JV
authors.lastname: Parambil
authors.affiliation: Surface Measurement Systems Ltd., 2125 28th Street SW, Suite 1, Allentown, Pennsylvania, 18103, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Burnett
authors.affiliation: Novartis Pharma, Technical Operations, Schaffhauserstrasse, 4322, Stein, Switzerland.
authors.forename: Frank
authors.initials: F
authors.lastname: Thielmann
authors.affiliation: Surfaces and Particle Engineering Laboratory, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. jerry.heng@imperial.ac.uk.
authors.forename: Jerry Y Y
authors.initials: JY
authors.lastname: Heng
mesh_terms: D002849:Chromatography, Gas; D003460:Crystallization; D018360:Crystallography, X-Ray; D004735:Energy Transfer; D008353:Mannitol / Q000737:chemistry*; D008956:Models, Chemical; D033362:Powder Diffraction; D013499:Surface Properties
chemical_list: D008353:Mannitol
keywords: D-mannitol; inverse gas chromatography; modelling; polymorphism; powder X-ray diffraction; surface energy heterogeneity