Probing Block-Copolymer Self-Assembly Kinetics with In-Situ Spectroscopic Ellipsometry

Understanding the assembly of block copolymers during various processing procedures is critical for the development of functional materials, as well as providing information on the underlying polymer physics. However, direct observation of the assembly process in-situ is exceedingly challenging and time-consuming. In this work, we develop and implement a novel characterization method to monitor the assembly of cylinder- and lamellar- forming block copolymers using spectroscopic ellipsometry, which tracks the optical anisotropy that results from microphase separation of the assembled domains. Measurements of the birefringence are well-correlated with surface AFM images and are in good agreement with the birefringence expected from simple geometric arguments. Furthermore, the fast sampling rate (1 sec) permits in-situ measurements of the polymer self-assembly during both thermal and solvent vapor annealing in a single, rapid measurement, and correlate with the . Ellipsometry thus presents a means to not only obtain information to inform future experimental parameters for obtaining ordered phases, but also may be utilized as a novel technique to study the assembly kinetics of soft materials.