A molecular dynamics simulation on the self-assembly of ABC triblock copolymers. 3. Effects of block composition in asymmetric triblock copolymers

The self-assembly of asymmetric ABC triblock copolymers in the ordered structure is investigated using an isothermal-isobaric molecular dynamics simulation. Unlike symmetric ABC triblock copolymers, more fascinating morphologies are observed in asymmetric ones because of a larger difference of incompatibility between the components. Various modes of self-assembly in assymmetric ABC triblock copolymers are also observed depending on the block composition. When the composition of block A is changed from 0.125 to 0.25 at the same f(B) = 0.25, the morphological transition from the 11 cylinder in cylinder" to "cylinders at cylinder" structure is observed in the simulation. In the case of ABC triblocks with f(B) = 0.5, a lamellar-type structure is changed to a cylinder-type structure with increasing the length of block A. When the mid-block length increases further to f(B) = 0.625, the "spheres on cylinder" structure is observed in both the A(10)B(50)C(20) and A(20)B(50)C(10) triblocks. From these results, the phase diagram of ABC triblock copolymers can be constructed.