Polymerization and Photoisomerization of Azobenzene Derivative Labeled Polystyrene Films for Free Volume Probing

Abstract

Research from the past three decades has shown that the properties of polymer thin films of less than 100 nm in thickness deviate substantially from bulk polymer properties. For these polymer thin films, the glassy dynamics are understood to have a role in the presence of the surface and the quality of the interface. Further, the glassy dynamics have been linked to the molecular mobility of polymers, which is directly correlated with the free volume within the polymer film. In previous studies, the distribution of polymeric free volume was evaluated by observing the photoisomerization of free photoisomerizable dye molecule probes within the polymer matrix. Moreover, the effects of varying the thickness of tagged polystyrene films on photoisomerization kinetics have been previously explored. However, the field is lacking research that has explored photoisomerization kinetics and free volume distribution together in polymer films. Local probing by this photoisomerization method is a critical area for the exploration of the effects of local free volume distribution and photoisomerization kinetics on glassy dynamics. Thus, in the research for this thesis project, several distinct azobenzene derivative labeled polymer films were created to study the distribution of local free volume distribution and photoisomerization kinetics. Bulk films of approximately 1 μm with varying azobenzene derivative labels were spin coated and examined in photoisomerization studies in preparation for future thin film studies.