Effect of crystal habits on the surface energy and cohesion of crystalline powders
Author(s)
Type
Journal Article
Abstract
The role of surface properties, influenced by particle processing, in particle–particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1 cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°. This is attributed to variations in surface chemical functionality at specific facets, and confirmed using X-ray photoelectron spectroscopy (XPS). Using a finite dilution inverse gas chromatography (FD-IGC) approach, the surface energy heterogeneity of powders was determined. The surface energy profile of different mefenamic acid crystal habits was directly related to the relative exposure of different crystal facets. Cohesion, determined by a uniaxial compression test, was also found to relate to surface energy of the powders. By employing a surface modification (silanisation) approach, the contribution from crystal shape from surface area and surface energy was decoupled. By “normalising” contribution from surface energy and surface area, needle shaped crystals were found to be ∼2.5× more cohesive compared to elongated plates or hexagonal cuboid shapes crystals.
Date Issued
2014-06-10
Date Acceptance
2014-06-07
Citation
International Journal of Pharmaceutics, 2014, 472 (1-2), pp.140-147
ISSN
1873-3476
Publisher
Elsevier
Start Page
140
End Page
147
Journal / Book Title
International Journal of Pharmaceutics
Volume
472
Issue
1-2
Copyright Statement
© 2014, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
Science & Technology
Life Sciences & Biomedicine
Pharmacology & Pharmacy
PHARMACOLOGY & PHARMACY
Crystal habit
Surface energy heterogeneity
Macroscopic single crystal
Solvent polarity
Crystal aspect ratio
Cohesion
INVERSE GAS-CHROMATOGRAPHY
I PARACETAMOL CRYSTALS
PARTICLE-SIZE
MEFENAMIC-ACID
SHAPE
MORPHOLOGY
SOLVENT
MICROCRYSTALLINE
HETEROGENEITY
CELLULOSE
Publication Status
Published