Soft nanoconfinement effects on the crystallization behavior of asymmetric poly(ethylene oxide)-block-poly(ε-caprolactone) diblock copolymers

摘要

The time- and temperature-related crystallization process for the structure transitions of asymmetric crystalline-crystalline diblock copolymers from the melt to crystallites was investigated with synchrotron simultaneous small-angle/wide-angle X-ray scattering. Two asymmetric poly(ethylene oxide)-poly(e-caprolactone) dibiock copolymers were chosen. It is found in the course of the copolymer crystallization that the shorter blocks are uncrystallizable in both of the asymmetric dibiock copolymers and final lamellar structures are formed in both of them. The final lamellar structure was confirmed from atomic force microscopy observations. The small-angle X-ray scattering data collected were analyzed with different methods for the early stage of crystallization. Guinier and Debye-Bueche plots indicate that there are neither isolated domains nor correlated domains formed before the formation of lamellae in the asymmetric dibiock copolymers during the crystallization process. The structure evolution was calculated according to the correlation function, and the soft nanoconfined crystallization behavior is discussed.