Structure and dynamics of polymer brushes near the Θ point: A Monte Carlo simulation

Abstract

Grafted polymer layers under variable solvent conditions are studied by Monte Carlo simulations using the bond fluctuation model. Structural information such as monomer density profiles, brush thickness, mean-square displacement of monomers, and positions of the monomers along the chain are obtained for temperatures above, at, and below the Θ point. In particular, the scaling of the brush thickness is formulated and verified by the simulation data. At the Θ point, more extensive simulations are performed to investigate the structural and dynamical properties. While the brush thickness at the Θ point agrees very well with the scaling and self-consistent field predictions, the latter deviate from our results for the monomer density profile and the distribution function of the free chain ends. It is not clear whether these deviations result from our chains being too short or from a basic inadequacy of the theory. For the dynamics at the Θ point, both the relaxation of the chain configurations and the mean-square time displacement of the chains are studied. The relaxation time τ for a polymer brush of chain length N and surface coverage σ are found to behave as τ∼N3σb with an apparent exponent b≂1.6. For poor solvent conditions below the Θ point, we find that the layer (with randomly fixed grafting sites) develops considerable lateral inhomogenity in its density, which has not been predicted by previous theories.

Quantitative determination of ion distributions in bacterial lipopolysaccharide membranes by grazing-incidence X-ray fluorescence

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Interaction of protamine with gram‐negative bacteria membranes: possible alternative mechanisms of internalization in Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa

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Challenges in Multiscale Modeling of Polymer Dynamics

“…Self-consistent field theoretical approaches have been excluded from this review, because the underlying principles were established and developed more than two decades ago [49][50][51][52]. Still, a number of important applications were newly added in the recent past, including block copolymers and nanocomposites [53]; screening effects in polyelectrolyte brushes [54]; mixed polymer brushes [55]; harvesting cells cultured on thermoresponsive polymer brushes [56,57]; morphology control of hairy nanopores [58]; and the effect of charge, hydrophobicity and sequence of nucleoporins on the translocation of model particles through the nuclear pore complex [59]; to mention a few.…”