Partitioning of Semiflexible Macromolecules into a Slit in Theta Solvent

Theory for Concentration and Solvency Effects in Size-Exclusion Chromatography of Polymers

“…Our simple model therefore explains the main trends. It does not capture the crossover at high concentrations in a ϑ solvent as found by Skrinarova and Cifra . This subtle effect may be related to the boundary condition at the wall: ideally we would like φ(0) = 0, but this is not easily accomplished in the MC simulations.…”

“…The trends in Figure are thus the same as in Figures and , where we discussed the chain-length dependency. We nevertheless show Figure separately because it enables a comparison with MC simulations for stiff chains by Skrinarova and Cifra. , These authors found that for χ = 0 there is hardly any effect of the chain stiffness, whereas in a ϑ solvent at low concentrations K is significantly lower for stiffer chains. For higher concentrations in a ϑ solvent the effect of chain stiffness is smaller; the simulation data even suggest a crossover, with K for stiff chains at high concentrations slightly higher than for flexible ones.…”

“…Considerable progress as to the concentration effect on K was obtained in Monte Carlo (MC) simulations on a lattice. ,,− The distribution coefficient, the density profiles in a slitlike pore, and different global and local characteristics (end-to-end distance, radius of gyration, coil anisotropy, fraction of gauche and trans bonds) as a function of concentration were calculated for both athermal and ϑ solvents. Also, the effect of chain flexibility was studied. , The overall trend is that K is small at low concentrations and increases strongly in a relatively narrow concentration region (the so-called weak-to-strong penetration 11 ), after which a more gradual increase is found. There is a strong effect of solvency: in a ϑ solvent the transition is steeper and occurs at a higher concentration than in a good solvent.…”

“…Also, the effect of chain flexibility was studied. 36,37 The overall trend is that K is small at low concentrations and increases strongly in a relatively narrow concentration region (the so-called weak-to-strong penetration 11 ), after which a more gradual increase is found. There is a strong effect of solvency: in a Θ solvent the transition is steeper and occurs at a higher concentration than in a good solvent.…”

Influence of the Chain Architecture and the Presence of End-Groups or Branching Units Chemically Different from Repeating Structural Units on the Critical Adsorption Point in Liquid Chromatography

“…The potential energy of the beads located at the corners, which are in contact with two walls simultaneously, is halved analogously to the model used by Zhu et al Periodic boundary conditions (PBC) are imposed in all three directions except for the impenetrable walls. Identical interaction parameters between all couples of neighboring nonbonded polymer beads are set as ε AA = ε BB = ε CC = ε AB = ε AC = ε BC = −0.2693 to model a Θ solvent. − The partitioning of chains between the bulk solution and the square pore was studied by the configurational-bias Monte Carlo (CBMC) algorithm described in our earlier reports . A number of 5 × 10 10 CBMC steps were performed after the equilibration period (about 10% of the length of the simulation run).…”