Adsorption of Block-Polyelectrolytes on an Oppositely Charged Surface

Abstract

Electrostatic interaction is widely considered to be the main driving force of the adsorption of polyelectrolytes (PEs) on an oppositely charged surface. Therefore, the alteration of charge distribution as a result of varying PE chain structures will directly affect the performance of the adsorption behaviors in the system at a certain monomer concentration. In this work, we studied the effects of chain structure (chain length, N m) as well as sequence variables including charge fraction and blockiness on the adsorption behaviors of block-PEs on an oppositely charged planar surface in the salt-free system using PE-Poisson–Boltzmann equations. Due to the complicated competitions among the translational entropies of PEs and counterions, the conformational entropy of PEs, and the surface attractive interactions, we find that the adsorption amounts show rich behaviors. First, the adsorption amounts of charged ζc and neutral ζn monomers both show two-stage behaviors, that is, ζc and ζn drastically increase with N m for short chains but moderately increase to an asymptotic value for relatively long chains. Second, the adsorption amounts of charged monomers show non-monotonic behaviors (increase first then decrease) with charge fraction. However, the adsorption amounts of neutral monomers monotonically decrease with charge fraction. Finally, when chain length and charge fraction are unchanged, the adsorption amounts of both neutral and charged monomers are independent of blockiness. Moreover, we find that overcharging can only appear when the bare surface charge density is low enough, while charge reversal and inversion can be observed in the entire range of the bare surface charge density with appropriate conditions. Additionally, our results indicate that the strength of charge reversal and inversion increases monotonically with chain length and charge fraction, while it changes non-monotonically with blockiness.

Nanoclay-based sensor composites for the facile detection of molecular antioxidants

“…Polyelectrolyte induced charge reversal of surfaces has been already published in the literature and it was related to entropy effects, ion correlations and hydrophobic interactions. [51][52][53] The trend in the stability ratios is in good agreement with the zeta potential values if one considers the presence of repulsive forces of electrostatic origin. Accordingly, at low doses, where the particles possess considerable positive charge, aggregation did not occur, i.e., the dispersions were stable.…”

“…Polyelectrolyte induced charge reversal of surfaces has been already published in the literature and it was related to entropy effects, ion correlations and hydrophobic interactions. 51–53…”

Software Package: An Advanced Theoretical Tool for Inhomogeneous Fluids (Atif)

“…Moreover, Atif integrates both cDFT and a self-consistent field theory (SCFT). [32,33] The users can choose one of the two methods arbitrarily to start their projects. In order to make it unnecessary for users to either know the computer language (such as C++ or FOR-TRAN) or seek an experienced collaborator, this designed software can be controlled completely via a readable input file.…”

Selective Adsorption of Confined Polymers: Self-Consistent Field Theory Studies

“…Selective adsorption, however, introduces an interesting variation on the adsorption problem that the sequence of stickers in the polymer chain leads to important modifications in adsorption phenomenology compared to the case of nonselective adsorption. ,,− …”

“…The selectivity can be provided by monomers characterized by different charges as in polyampholyte or other chemical properties as in amphiphilic polymer. In the case of polyampholyte, previous theoretical studies have shown a complicated dependence of adsorption on the charge distribution along the chain and the flat surface composition. − However, for amphiphilic polymers confined in a curved pore with non-Coulombic interaction between the stickers and the surface, according to our best knowledge, the theoretical study is still limited, resulting in a lack of understanding of the underlying mechanism of the relation between the sticker sequence and adsorption behavior of polymers.…”