No abstract

SUMMARY Short block copolymers in selective solvents (bad for A-block, good for B-block) are modeled by flexible bead-spring chains, where beads interact with short range Morse potentials of variable strength. It is shown that already very short chains ( N A = NB = 2) exhibit a rather well-defined critical micelle concentration (cmc). The mass distribution of the micelles and their gyration tensor components as well as their internal structure are studied. It is shown that the relaxation time increases exponentially with the strength EAA of the attractive energy between the A-monomers, and thus frozen-in micelles of medium size are obtained when E A A is chosen too large. Our results are compared to studies of related but somewhat different models.

We present the model of a cylindrical pore with chains tethered by one end to its inner surface. The conformational and “quasistatic” (under low and medium shear rates) hydrodynamic properties of the system are studied. Since it was shown by other researchers that the density profile of the polymer layer is only slightly affected by flow in the region of low and medium shear rates, we do not take flow into account when calculating chain conformations. The conformational properties of the concave layer are very similar to those of the flat one. They are characterized by the layer thickness h. The hydrodynamic properties are characterized by the hydrodynamic thickness Lh. We show that Lh depends strongly on the chain surface density σ under conditions of the “mushroom” regime in contrast to h. Finally, we predict that the net permeability of the cylinder could decrease with the increasing temperature. It enables us, principally, to control the pore permeability with temperature.

No abstract