AbstractTransmission electron microtomog. (TEMT) is a rapidly growing anal. technique that holds tremendous promise for providing valuable insight into polymeric nanostructures, esp. those that are geometrically complex or that evolve with time or environmental conditions. The approach adopted here is based on single-tilt tomog. in conjunction with filtered back projection. In this work, we report on several different multicomponent block copolymer morphologies that have been recently investigated by TEMT. Using cryogenic imaging conditions, one study addresses the dispersed morphologies of block copolymers in the presence of solvent. Another series explores blends of ABC triblock copolymers, while a third seeks to elucidate the behavior of block copolymer mols. in the presence of other network-forming additives. Lastly, we demonstrate how TEMT can be used to discern the mechanism by which block copolymer self-assembly proceeds in a highly nonequil., dynamically evolving thin-film environment.