Polymer thin films have been studied for applications in a wide range of industries, including biomedical and food packaging. Polymers can be classified as amorphous or semi-crystalline, and their degree of crystallinity greatly affects the applications a polymer is suitable for. For thin film applications, understanding changes in crystallization mechanisms and morphology due to confinement effects is of particular interest as morphology is directly related to material properties. Prior work has identified morphological changes in thin films of semi-crystalline poly(ε-caprolactone) (PCL) blended with poly(styrene-isoprene-styrene) (SIS) block copolymers which gives rise to the nano-rose morphology, a structure consisting of curved crystals 500 nm in diameter that resembles a cluster of roses. Additional triblock copolymers, poly(styrene-b-dimethylsiloxane-b-styrene) (SDS), poly(styrene-b-butadiene-b-styrene) (SBS), and poly(styrene-b-(ethylene-ran-butylene)-b-styrene) (SEBS) were studied in blends with PCL to determine the extent of the nano-rose behavior. We have seen that the nano-rose morphology occurs in these other PCL/block copolymer blends within the same film thickness window as PCL/SIS, but there are differences in nucleation and growth rates associated with the chemistry and modulus of the block copolymer. For further insight into the crystallization mechanism for the nano-rose morphology, fast scanning atomic force microscopy (AFM) methods were developed and utilized to visualize in situ crystallization. Flipbook-style videos were obtained by capturing images approximately every 13 seconds during crystallization. Using a code to estimate the fraction of crystalline material in each image, we were able to compare the crystallization rates of PCL blended with SIS, SBS, and SDS. SEBS dewet too rapidly to observe crystallization in real time. In addition to fast scanning AFM, we took advantage of the programmable stage on our AFM. Moves were programmed to create a six image by six image grid to create an extended field of view to observe how many PCL crystals nucleated within an approximately 100 micron by 100 micron area. By using the data obtained from AFM, calculated surface energy values, and measured Young’s modulus values, we determined that the formation of the nano-rose morphology occurs due to an interplay between thin-film confinement and the physicochemical properties of the block copolymer.