Modulation of Polyelectrolyte Adsorption on Nanoparticles and Nanochannels by Surface Curvature

Abstract

This paper presents theoretical results on the adsorption of polyelectrolyte chains on surfaces with opposite charge and nanoscale curvature. The theory predicts that increasing surface curvature can either increase or decrease the amount of adsorbed polyelectrolyte, depending on the type of curvature (convex or concave) and whether the polyelectrolyte undercompensates or overcompensates the initial charge of the substrate. For small bulk salt concentration (10-4 M), increasing the curvature of the surface displaces the adsorption equilibrium of the polyelectrolyte in order to decrease the effective charge density for concave surfaces (nanochannels) or to increase it for convex surfaces (nanoparticles). This behavior is traced back to the dependence the total free energy as a function of the curvature of the surface. For intermediate salt concentrations (0.01 M-0.1 M), the magnitude of the effect is larger than for low salt concentrations, although the general picture becomes more complex due to the fact that the added salt competes with the polycation to screen the negative charge of the substrate. It is argued that the effect under discussion will be relevant for nanoobjects that have different radii or type of curvature at different locations (i.e. conical nanochannels or cylindrical nanorods with hemispherical tips) as our theory predicts inhomogeneous polyelectrolyte adsorption on their surfaces.

Bioinspired Dual-Responsive Nanofluidic Diodes by Poly-l-lysine Modification

“…Many kinds of polymers or polyelectrolytes can be functionalized on to the inner surface of nanopores by noncovalent bonds. − PLL can be easily assembled on the inner surface of negatively charged nanopores during the strong electrostatic interaction with hydrophilic and abundant positively charged PLL. We coated a stabilized layer of PLL on the inner surface of the nanopores by immersing it in PLL aqueous solution for 4 h. , The tailor chemistry and responsive wettability of the amphoteric PLL enables to construct functional nanofluidic devices.…”

Molecular Design of Solid‐State Nanopores: Fundamental Concepts and Applications

“…In recent years, the modification of solid‐state nanopores via polyelectrolyte assembly/adsorption has gained increasing interest . The LbL assembly of polyelectrolytes represents a very simple and versatile chemical method to create functional thin films with nanoscale precision .…”

Hierarchical Assemblies of Polymer Particles through Tailored Interfaces and Controllable Interfacial Interactions

“…[ 23 ] Polyelectrolytes positioned at the oil–water (hydrophobic–hydrophilic) interface of the polymer nanoparticles and protecting as well as controlling the surface state of nanoparticles during the growth process. [ 74–80 ] As shown in Figure A the initial emulsion of both immiscible phases (organic monomer phase and polyelectrolyte dissolved aqueous phase) was realized through microreactor and further polymerization takes place externally at the heating block. [ 23 ] Once the polymerization starts at polymerizing temperature, it can be imagined that the monomer units are continuously added to proceed with the growth of nanoparticles upon movement of the polyelectrolyte that lied at the surface of nanoparticles.…”