Wh. Jo et Ss. Jang, Monte Carlo simulation of the order-disorder transition of a symmetric cyclic diblock copolymer system, J CHEM PHYS, 111(4), 1999, pp. 1712-1720
The microphase separation of symmetric cyclic diblock copolymer with decrea
sing temperature is simulated using the Monte Carlo method. In order to inv
estigate the effect of the ring-shape chain architecture on order-disorder
transition (ODT), the microphase separation of the cyclic diblock copolymer
is compared with that of a symmetric linear diblock copolymer with the sam
e chain length. For both systems, the ODT is observed as a first-order tran
sition, and the ordered structure formed through the ODT is lamellar. The r
atio of the domain spacing in the cyclic diblock copolymer to that in the l
inear one is 0.7 at the ODT, and the scattering intensity of the former is
weaker than that of the latter. The ring-shape chain architecture suppresse
s the random thermal force, so that the cyclic diblock copolymer still show
s a mean-field behavior at the temperature at which the linear diblock copo
lymer does not obey the mean-field prediction. The value of (chi(eff)N)(ODT
) of the linear diblock copolymer is calculated to be in the range of 25.36
<(chi(eff)N)< 26.04, which is in good agreement with the theoretical predi
ction, (chi(eff)N)(ODT)=25.61, indicating that this simulation properly des
cribes the ODT of the diblock copolymer. The value of (chi(eff)N)(ODT) of t
he cyclic diblock copolymer is predicted to be in the range of 40.83 <(chi(
eff)N)< 43.02. (C) 1999 American Institute of Physics. [S0021-9606(99)51228
-2].