Atomic force microscopy studies of polymeric, metallic, and biological surfaces

This thesis contains four independent research projects on which we have conducted atomic force microscopy (AFM) imaging studies. Systems include polymeric, metallic and biological samples; (i) asymmetric polystyrene-block-polymethylmethacrylate (PS-b-PMMA) diblock copolymer ultrathin films, (ii) Ni and Al 2024-T3, (iii) pure aluminum, and (iv) cell membrane structure of antibiotic resistant strains of Staphylococcus aureus.; The first chapter discusses direct observation of asymmetric PS-b-PMMA diblock copolymer ultrathin films. We have investigated ultra-thin films of microphase-separating PS-b-PMMA. One aspect of our work deals with polymer annealing dynamics in which the evolution of individual topological defects in the microdomain pattern of cylinder-forming films have been temporally tracked using AFM. For the first time, we have shown time lapse AFM data of such topological defect evolution and developed mathematical combining rules to elucidate basic defect interaction mechanisms. We have also examined the mobility of defect structures and the formation of highly-ordered annuli under various annealing conditions.; In the second chapter, we report stress-modified electrochemical reactivity of metallic surfaces of Ni and Al 2024-T3. We have investigated the effects of externally applied tensile and compressive stresses on the electrochemical behavior of these pure and alloyed metals. We have demonstrated that externally applied tensile and compressive stresses can systematically modify the electrochemical surface reactivity of these metals. AFM is used to statistically characterize the extent and nature of interface change for these metals subjected to electrochemical conditions under varying levels of stress.; The third chapter describes in situ AFM study of pure aluminum grain dissolution and pit evolution. We have elucidated morphological and dynamical changes in metal surfaces under chemical environments. Pits with various geometries are investigated to understand how their crystallographic orientations influence the reaction dynamics. Also, we report the associated reaction kinetics of grain dissolution and pit evolution.; Lastly, we investigate cell membrane structure of antibiotic resistant strains of Staphylococcus aureus in the fourth chapter. We have participated on a recent breakthrough in imaging and discriminating genetically related drug susceptible/resistant bacterial cell surfaces and elucidated fine topological differences by sampling large sets of bacterial cells which exhibit drug resistance.