  In this work we investigated the phase behavior of melts of block-copolymers
with one charged block by means of dissipative particle dynamics with explicit
electrostatic interactions. We assumed that all the Flory-Huggins \c{hi}
parameters were equal to 0 and showed that the charge correlation attraction
solely can cause microphase separation with long-range order; a phase diagram
was constructed by varying the volume fraction of the uncharged block and the
electrostatic interaction parameter {\lambda}. The obtained phase diagram was
compared to the phase diagram of corresponding neutral diblock-copolymers.
Surprisingly, the differences between these phase diagrams are rather subtle;
the same phases are observed, and the positions of the ODT points are similar
if the {\lambda}-parameter is considered as an "effective" \c{hi}-parameter.
Next, we studied the position of the ODT for lamellar structure depending on
the chain length N. It turned out that while for the uncharged
diblock-copolymer the product \c{hi}crN was almost independent of N, for the
diblock-copolymers with one charged block we observed a significant increase in
{\lambda}crN upon increasing N. It can be attributed to the fact that the
counterion entropy prevents the formation of ordered structures. This was
supported by studying the ODT in diblock-copolymers with charged blocks and
counterions cross-linked to the charged monomer units. The ODT for such systems
was observed at significantly lower values of {\lambda} with the difference
being more pronounced at longer chain lengths N. The diffusion of counterions
in the obtained ordered structures was studied and compared to the case of a
system with the same number of charged groups but homogeneous structure; the
diffusion coefficient in a direction in the lamellar plane was found to be
higher than in any direction in homogeneous structure.
