Crystallization-Induced Microdomain Coalescence in Lamellar Diblock Copolymers Studied by Dynamic Monte Carlo Simulations

摘要

A numerical study of microdomain coalescence induced by the soft-confined crystallization of lamellar diblock copolymers has been reported.It was found that under high temperatures those crystallites showing their orientational preferences perpendicular to the lamellar microdomains are responsible for the occurrence of coalescence,whereas the segregation strength just plays a subsidiary role.In addition,the lamellar microdomains are well preserved with undulations at the stage of primary crystallization but be broken out by the crystal thickening at the subsequent stage of isothermal annealing.Down with the temperature,there exists an abrupt transition from perpendicular to random in the preference of crystallite orientations.Annealing the nascent crystals of variable orientational preferences demonstrates that at low temperatures a randomization in the crystallite orientations may prevent microdomains from coalescing.The mechanisms of undulation and coalescence were thus discussed on the basis of the microphase-interface tension enhanced by the crystal thickening.