Polyelectrolyte Complexes Consisting of Macromolecules With Varied Stiffness: Computer Simulation

Abstract

Monte Carlo simulations are employed in order to analyze the structure of polyelectrolyte complexes consisting of two identical but oppositely charged macroions with varying chain stiffness. It is shown that two complex structures can arise depending on the stiffness of the constituent chains. Stiff chains are organized into a ''ladder'' structure in which chains are located parallel to each other and monomeric units are arranged into ionic pairs according to their position in the chain. Flexible chains form a globular ''scrambled-egg'' structure with a disordered position of monomer units. The conformational transition between the two structures proceeds as a phase transition.

Pressure sensitive adhesives based on interpolymer complexes

“…Within a complex of flexible macromolecules (ε st =0) the total number of long-range electrostatic bonds is rather high, while at high backbone stiffness (ε st > 8) such bonds are totally absent [186]. In full agreement with the prediction of the statistical theory of globular polyelectrolyte complexes [163], the structural transformation of PECs from the ''ladder'' to ''scrambled egg'' structure may be treated as a phase transition [186].…”

“…The dependence of the mean order parameter η on the stiffness parameter ε st for macromolecules of different lengths N is shown in Figure 24 [186]. One can see that the order parameter increases with the growth of macromolecule stiffness ε st and that for different…”

“…In real systems the intermediate case is often encountered: oppositely charged units form ion pairs but the chains are randomly mixed (entangled) to some extent [186]. The dependence of the mean order parameter η on the stiffness parameter ε st for macromolecules of different lengths N is shown in Figure 24 [186].…”

“…In the course of complex formation some ionic pairs can be destroyed and then reformed again. The longer is the macromolecule the higher is the disorder leading to smaller values of the ladder order parameter at both high and low macromolecule stiffness ε st [186].…”

Marked difference in conformational fluctuation between giant DNA molecules in circular and linear forms

“…While the off-lattice simulation imposes limitations on the speed of computation, monomer units are not bound to lattice sites, which is a distinct advantage for modeling semiflexible macromolecules equipped with stiffness. [26][27][28] In our model, each monomer unit is bonded to the neighboring units along the chain, and also to the corresponding monomer on the other chain. We assume that the natural lengths of the bonds are represented by the bond potential E b in the form of a square wall potential,…”