14 research outputs found
Polyelectrolytes in the presence of multivalent ions: gelation versus segregation
We analyze solutions of strongly charged chains bridged by linkers such as
multivalent ions. The gelation induced by the strong short range electrostatic
attractions is dramatically suppressed by the long range electrostatic
correlations due to the charge along the uncrosslinked monomers and ions. A
modified Debye-Huckel approach of crosslinked clusters of charged chains is
used to determined the mean field gelation transition self-consistently. Highly
dilute polyelectrolyte solutions tend to segregate macroscopically. Semidilute
solutions can form gels if the Bjerrum length and the distance between
neighboring charged monomers along the chain are both greater than the ion
size
Association Equilibrium and Gelation in Solutions of Cross-Associating Chains Containing Inactive Fragments
Fluctuation Effects on Microphase Separation in Random Copolymers
We study random copolymers consisted of two kinds of monomers with attraction
between similar kinds. The mean field analysis of this system indicates a
continuous phase transition into a phase with periodic microdomain structure.
It is shown that the inverse of the renormalized propagator has a minimum at
non-zero wave-numbers. Consequently, there is an anomalously large contribution
of fluctuations that make the disordered phase locally stable at every finite
temperature. However, below a certain temperature, the ordered phase is shown
to be locally stable and a weak first order transition is possible, similar to
the weak crystallization theory developed by Brazovskii.Comment: 20 pages, RevTex, includes two uuencoded figure