Phase behavior of symmetric linear multiblock copolymers

Molecular-dynamics simulations are used to study the phase behavior of a single linear multiblock copolymer with blocks of A- and B-type monomers under poor solvent conditions, varying the block length N, number of blocks n, and the solvent quality (by variation of the temperature T). The fraction f of A-type monomers is kept constant and equal to 0.5, and always the lengths of A and B blocks are equal (NA=NB=N), as well as the number of blocks (nA=nB). We identify the three following regimes where: i) full microphase separation between blocks of different type occurs (all blocks of A-type monomers form a single cluster, while all blocks of B-type monomers form another); ii) full microphase separation is observed with a certain probability; and iii) full microphase separation cannot take place. For a very high number of blocks n and very high N (not accessible to our simulations) further investigation is needed.