A molecular dynamics simulation on the self-assembly of ABC triblock copolymers, 1 - Effects of block composition in symmetric triblock copolymers

The self-assembly of ABC triblock copolymers in the microphase-separated st ate is investigated using an isothermal-isobaric molecular dynamics simulat ion. For the validation of our simulation scheme, ABA triblock copolymers a re also simulated. We examine the effect of the composition (f(B)) of symme tric triblock copolymers on the morphology realized in these copolymers, ke eping other parameters fixed. For ABA triblock copolymers, the transition f rom lamellar to cylindrical morphologies is observed with increasing the co mposition from f(B) = 0.5 to f(B) = 0.75, and such behavior is supported by calculation results of scattering patterns. These simulated results agree well with experimental and theoretical ones, validating our simulation meth od. More complex structures are predicted for ABC triblock copolymers. If m id-block B is the minor component, its structures are changed from lamellar , cylindrical, to spherical morphology at the interface between AIC lamella e as f(B) decreases. For ABC triblock copolymers with the midblock B as the major component, the morphology of end blocks in the matrix composed of th e midblock is changed from tricontinuous to spherical structures as f(B) in creases.