Date of Award
Master of Science in Engineering
Chemical and Paper Engineering
Dr. Kalyana Chakravarty Pingali
Dr. Andrew Kline
Dr. Brian Young
Dr. James Springstead
Atomic force microscope, crystallization, adhesion forces, physical vapor deposition, active pharmaceutical ingredient
Masters Thesis-Open Access
The overall objective of this research work is to investigate the hydrophilic and hydrophobic forces acting on organic crystal planes and understanding the interaction of functional groups with additive molecular nanolayers. Crystals of acetaminophen and lactose were made and the surface forces were tested on Atomic Force Microscope (AFM). Uniformity of crystal surface was confirmed from the AFM study in the first stage. The growth factors of crystal planes as a function of time were studied. Adhesion forces on plain crystals were measured on both two different organic crystals made of acetaminophen and lactose. In the second stage, the crystals were coated with 10, 20 and 50 nm thick SiO2 nanolayers using Physical Vapor Deposition (PVD). The adhesion forces were compared to that of the plain crystals measured in the first stage. In the third stage, two different AFM probes were functionalized with hydrophobic and hydrophilic functional groups of decane thiol and octanoic acid. In the fourth stage, the AFM forces were measured on the SiO2 coated crystals with the functionalized AFM probes. Surface topography was found to change as a function of time. Uniformity and thickness of PVD coating was found to increase the adhesion forces on both crystals. Hydrophilic functionalization increased the adhesion force of SiO2 coating. Hydrophilic functionalized groups were found to possess higher adhesion force than hydrophobic functional groups on SiO2 nanocoated crystals. Chemical nature of crystal molecule was found to dramatically affect the adhesion force of functionalized group.
Krishnan, "Measurement of Activity and Stability of Physical Vapor Deposition (PVD) Coated Crystal Surfaces" (2016). Master's Theses. 753.