Polyelectrolyte brushes: theory, modelling, synthesis and applications

Abstract

Polyelectrolyte (PE) brushes are a special class of polymer brushes (PBs) containing charges. Polymer chains attain "brush"-like configuration when they are grafted or get localized at an interface (solid-fluid or liquid-fluid) with sufficiently close proximity between two-adjacent grafted polymer chains - such a proximity triggers a particular nature of interaction between the adjacent polymer molecules forcing them to stretch orthogonally to the grafting interface, instead of random-coil arrangement. In this review, we discuss the theory, synthesis, and applications of PE brushes. The theoretical discussion starts with the standard scaling concepts for polymer and PE brushes; following that, we shed light on the state of the art in continuum modelling approaches for polymer and PE brushes directed towards analysis beyond the scaling calculations. A special emphasis is laid in pinpointing the cases for which the PE electrostatic effects can be de-coupled from the PE entropic and excluded volume effects; such de-coupling is necessary to appropriately probe the complicated electrostatic effects arising from pH-dependent charging of the PE brushes and the use of these effects for driving liquid and ion transport at the interfaces covered with PE brushes. We also discuss the atomistic simulation approaches for polymer and PE brushes. Next we provide a detailed review of the existing approaches for the synthesis of polymer and PE brushes on interfaces, nanoparticles, and nanochannels, including mixed brushes and patterned brushes. Finally, we discuss some of the possible applications and future developments of polymer and PE brushes grafted on a variety of interfaces.

Droplet Transport in a Nanochannel Coated by Hydrophobic Semiflexible Polymer Brushes: The Effect of Chain Stiffness

“…Polymers tethered to a surface through a terminal monomer (polymer brushes) are good candidates to be used as coating in microchannels, due to their responsiveness to stimuli (pH, temperature, electric field, etc) and the ability to modify the rheological conditions [34][35][36][37][38][39] . Polymer brushes present a very wide range of applications, like phcontrolled nanopores 40 , catalysis in microreactors 41 and cell adhesion and detachment control 42 .…”

Synthesis and characterization of lignin‐based cationic dye‐flocculant

“…Although the actual shape of core‐lignin in aqueous solution was not clear in this study, the esterified aromatic skeleton should be hydrophobic and we illustrated it as a particle at the center of the flocculant molecule to make the scheme simple. The side chains should have expanding character in neutral pH because of their intramolecular ionic repulsion which enables the stable dispersion of the flocculant molecules . When the anionic dyes and the flocculants are mixed in the solution, the electrostatic coupling makes the molecules neutral and decreases their water solubility.…”

Electrokinetics in polyelectrolyte grafted nanofluidic channels modulated by the ion partitioning effect

“…[7][8][9] Ions moving in the upstream direction pull the liquid molecules opposite to the pressure driven flow, an effect similar to the fluid having an amplified apparent viscosity. [19][20][21][22] Researchers have directed significant efforts to 4 understand the electrokinetics of colloidal particles coated with an ion-penetrable layer of adsorbed charged polymers. [7][8][9] Electrokinetic phenomena in pressure driven flows have been considered to be pivotal in converting hydraulic power to electrical power.…”