  Brownian Dynamics simulations are carried out to understand the effect of
temperature and dielectric constant of the medium on microphase separation of
charged-neutral diblock copolymer systems. For different dielectric media, we
focus on the effect of temperature on the morphology and dynamics of model
charged diblock copolymers. In this study we examine in detail a system of
partially charged block copolymer consisting of 75% neutral blocks and 25% of
charged blocks with 50% degree of ionization. Our investigations show that due
to the presence of strong electrostatic interactions between the charged block
and counterions, the block copolymer morphologies are rather different than
their neutral counterpart at low dielectric constant, however at high
dielectric constant the neutral diblock behaviors are observed. This article
highlights the effect of dielectric constant of two different media on
different thermodynamic and dynamic quantities. At low dielectric, the
morphologies are a direct outcome of the ion-counterion multiplet formation. At
high dielectric, these charged diblocks behavior resembles that of neutral and
weakly charged polymers with sustainable long-range order. Similar behavior has
been observed in chain swelling, albeit with small changes in swelling ratio
for large change in polarity of the medium. The results of our simulations
agree with recent experimental results and are consistent with recent
theoretical predictions of counterion adsorption on flexible polyelectrolytes.
