Neutron Studies of Multi-Component Polymer Thin Films: Stratification and Interfacial Structure

This dissertation presents the impact fabrication conditions have upon layer composition, purity, and interfacial clarity of multi-component thin films on both rigid and flexible substrates. The performance of the multi-functional thin films is directly linked to the macroscopic assembly in a thin film. Prior to production of a novel thin film systems, the suitable fabrication methods required for optimum performance must be determined. Oftentimes, this is pursued on a tedious trial and error basis. Thus, guidelines established upon the thermodynamic and kinetic properties of the thin film are essential for improving processing efficiency and enhancing overall product performance.Chapter Two of this dissertation outlines the procedure for a novel method of quantifying the stratification of polymer blend thin films. Application of this technique revealed definitive control over the final film depth profile simply by altering the processing conditions. Instead of simply stating the effect of processing condition upon the final film depth profile and the extent of stratification, each processing condition was reported as the thermodynamic and kinetic properties of fabrication. Chapter Three expands upon the thermodynamic driving forces responsible for stratification outlined in Chapter Two and describes a hierarchy of thermodynamic properties responsible for stratification. Both Chapter Two and Three investigate the vertical stratification of a polymer blend. Chapter Four considers the lateral phase separation of the blend under the same thermodynamic and kinetic parameters. Chapter Five investigates the extent of control substrate rigidity has upon the order of the thin film and the order at each interface of sputtered multi-layer thin films.Ultimately, this work provides strong evidence that each processing parameter influences the entire structure of thin films. Control of polymer processing (either as a blend or as substrates) is crucial for product and thin film fabrication. The lack of control during processing will result in inconsistent final film structures, a film feature known to impact product performance. With the knowledge of stratification control and substrate influence upon final film structure, this information can be tailored to a diverse collection of polymer blended systems and endless multi-component applications.