1 research outputs found
Correlated disorder in random block-copolymers
We study the effect of a random Flory-Huggins parameter in a symmetric
diblock copolymer melt which is expected to occur in a copolymer where one
block is near its structural glass transition. In the clean limit the
microphase segregation between the two blocks causes a weak, fluctuation
induced first order transition to a lamellar state. Using a renormalization
group approach combined with the replica trick to treat the quenched disorder,
we show that beyond a critical disorder strength, that depends on the length of
the polymer chain, the character of the transition is changed. The system
becomes dominated by strong randomness and a glassy rather than an ordered
lamellar state occurs. A renormalization of the effective disorder distribution
leads to nonlocal disorder correlations that reflect strong compositional
fluctuation on the scale of the radius of gyration of the polymer chains. The
reason for this behavior is shown to be the chain length dependent role of
critical fluctuations, which are less important for shorter chains and become
increasingly more relevant as the polymer length increases and the clean first
order transition becomes weaker.Comment: 11 pages, 5 figures, submitted to PR