X-ray Photon Correlation Spectroscopy in Linear Diblock Copolymer Melts

The specific dynamic processes which govern ordering in diblock copolymer melts are still largely unknown. Techniques such as Time-Resolved Small Angle X-ray Scattering and Rheology have been used in the past to characterize ordering kinetics, but these techniques generally lack the capability to decouple individual characteristic timescales of the system. To this end, we have employed X-ray Photon Correlation Spectroscopy (XPCS), a relatively new technique in soft materials, to further understand the kinetic mechanisms for ordering in linear diblock copolymers. Specifically, a series of model diblock copolymers with varying chemistry, composition, and molecular weight were investigated at several temperatures. The conclusions of this work are two-fold: i) XPCS is a feasible technique for measuring characteristic timescales of diblock copolymers, and ii) ordered diblock copolymers exhibit unique heterodyne mixing behavior under specific conditions. This work motivates additional XPCS studies to further elucidate the dynamics of ordering in diblock copolymer melts, as well as other related soft material systems.