title: Relation between surface roughness of free films and process parameters in spray coating.
abstract: A novel spraying apparatus was developed to obtain reproducible free sprayed films. Aqueous solutions of PolyVinyl Alcohol PVA 4-98, HydroxyPropyl MethylCellulose HPMC 603 and HPMC 615 were used as reference coating materials. The apparatus is composed by a spraying system, a closed chamber containing a rotating Teflon cylinder, a pressured air supply system, a spray solution supply system, and a computerized control system. The spraying air pressure, the cylinder rotation speed, and the cylinder-spray nozzle distance were tailored in such a manner that the roughness of the obtained free films was similar to that from reference coated particles. Optimum spraying process conditions were found for all three coating materials using design of experiments. The morphology of the sprayed films obtained using the optimum conditions is evaluated by means of scanning electron microscopy (SEM), and atomic force microscopy (AFM), and then compared with those from corresponding cast films and coating layers on particles. A match was found between the morphology of sprayed films and that from the corresponding coating layer on the particle surface. The spray apparatus produced reproducible sprayed films with tuneable roughness and/or smoothness depending on the set of processing parameters.
authors.affiliation: Nanostructured Materials Group, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, NL-2628 BL Delft, The Netherlands. g.perfetti@tudelft.nl
authors.forename: G
authors.initials: G
authors.lastname: Perfetti
authors.forename: T
authors.initials: T
authors.lastname: Alphazan
authors.forename: P
authors.initials: P
authors.lastname: van Hee
authors.forename: W J
authors.initials: WJ
authors.lastname: Wildeboer
authors.forename: G M H
authors.initials: GM
authors.lastname: Meesters
mesh_terms: D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D004364:Pharmaceutical Preparations; D015203:Reproducibility of Results; D013499:Surface Properties; D013500:Surface Tension; D014783:Viscosity
chemical_list: D004364:Pharmaceutical Preparations