Optical characterization of ordering and disordering of block copolymer microstructure

Phenomena associated with the order-disorder transition (ODT) of block copolymers were studied on symmetric poly(styrene-b-methyl methacrylate) diblock samples. Ordering and disordering are clearly indicated by birefringence and a light intensity measurement. The transition temperatures were compared to rheologically-determined ODT temperatures. The optical measurements point to complex behavior near the ODT, including an apparent ∼3°C increase in the disorder temperature upon annealing as well as apparent gradual disordering over a 5-7°C temperature range