Fractal analysis of surface roughness and study of etching mechanism of acetaminophen single crystals
Abstract
Two separate research projects were conducted and are reported here. The first one was to characterize surface roughness of pharmaceutical granules and powders with fractal analysis approach. Atomic force microscope (AFM) was used to obtain three-dimensional surface profiles. The variation method was employed to calculate fractal dimensions. Results of fractal analysis of four wet granule samples, raw powder materials (Di-Tab, Ac-Di-Sol, Avicel and mannitol), and freeze-dried mannitol powders revealed an intrinsic relationship between fractal dimension and the underlying processes that produced the material and formed the surface morphology. Nanoscale measurements with AFM are able to reveal influences of the underlying molecular-level physicochemical processes. For the mechanically processed materials, however, larger-scale measurements may have to be used. The second project was to determine the dissolution or etching mechanism of acetaminophen single crystals on the molecular level. Partial dissolution tests were conducted on the (010) face with a few selected solvents. Surface textures and etching patterns were observed and collected with AFM. A computer model was proposed to simulate the dissolution process. Simulation results indicate that the experimentally observed etching patterns may be the result of essential molecular events during the dissolution process, surface diffusion. Furthermore, the diffusion is guided or confined by underlying crystal structures, especially the supramolecular interaction network
Degree
Ph.D.
Advisors
Park, Purdue University.
Subject Area
Pharmacology|Condensation|Materials science
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.