title: Application of time-dependent sessile drop contact angles on compacts to characterise the surface energetics of sulfathiazole crystals.
abstract: The time-dependent wetting of sulfathiazole compacts with sessile water drops was evaluated using video microscopy. The influence of sulfathiazole crystalline form, particle size, pre-saturation with water, humidity and compaction pressure on the droplet spreading kinetics and contact angles are reported. The rate and extent of droplet spreading decreased for compact surfaces of high microscopic roughness; this was determined by atomic force microscopy (AFM). Pre-saturation of powder compacts with water (pre-saturated with sulfathiazole) enhanced droplet spreading and enabled pseudo-equilibrium contact angles to be determined for up to 10 min. Sessile-drop contact angles on both sulfathiazole powder compacts and single crystals are compared with particle contact angles determined by liquid penetration. This study has led to an improved understanding of the influence of physical heterogeneities and the face-specific surface chemistry of individual crystals on the wetting characteristics of pharmaceutical compacts.
authors.affiliation: Ian Wark Research Institute, University of South Australia, The Levels Campus, Mawson Lakes, SA 5095, Australia.
authors.forename: Tim H
authors.initials: TH
authors.lastname: Muster
authors.forename: Clive A
authors.initials: CA
authors.lastname: Prestidge
mesh_terms: D000465:Algorithms; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D018360:Crystallography, X-Ray; D004339:Drug Compounding; D006813:Humidity; D018625:Microscopy, Atomic Force; D010316:Particle Size; D016062:Porosity; D011208:Powders; D011312:Pressure; D013432:Sulfathiazoles / Q000737:chemistry*; D013499:Surface Properties; D013818:Thermogravimetry; D013997:Time Factors
chemical_list: D011208:Powders; D013432:Sulfathiazoles