In Situ Investigations of Polyelectrolyte Film Formation by Second Harmonic Generation

Abstract

Multilayer films of polyelectrolytes can be prepared by sequential immersion of a charged silica surface into cationic and anionic polyelectrolyte solutions. The formation of such films was investigated using second harmonic generation (SHG), yielding real time information about the in situ adsorption process of each layer within the multilayer film. The SHG results indicate the existence of a fast process (<10 s) that can be ascribed to the initial polymer adsorption to the surface, followed by a slower relaxation due to a change in polyelectrolyte conformation at the surface. The time scale for the reconfiguration varies with the polyelectrolyte.

Highly crosslinked layer-by-layer polyelectrolyte FO membranes: Understanding effects of salt concentration and deposition time on FO performance

“…During LbL membrane preparation via dipping method, polyelectrolyte layers were formed on the charged porous supports via a two-step process: a fast deposition of polyelectrolytes onto the supports and then a slow reconfiguration of polyelectrolyte layers [41]. In other words, polyelectrolytes firstly diffused from the dilute bulk solution to the support's surface and were subsequently adsorbed onto the oppositely charged substrate via electrostatic interaction.…”

Layer-by-layer self-assembled polyelectrolyte membranes for solvent dehydration by pervaporation

“…The adsorption of polyelectrolytes onto an oppositely charged non-porous surface is reported to be a two-step process, i.e., fast adsorption to the surface, and slower relaxation due to a change in polyelectrolyte conformation at the surface [26]. This mechanism may also apply to the formation of a self-assembled polyelectrolyte membrane over a microporous substrate if the size of polyelectrolyte is much larger than the pores on the substrate.…”

Electrostatic Layer-by-Layer Self-Assembly for Tuning Hydrophilic ITO glass to Wenzel Super Hydrophobic Surface

“…It is indicated by some study that the polymer deposition consists of initial adsorption and subsequent reconfiguration, which take several tens and hundreds of seconds, respectively. [26,27] The result of most polymers are deposited on the substrate in the initial several seconds, it is still necessary to extend the deposition time to 5 to 20 min to reach the equilibrium thickness. Meanwhile, to avoid cross-contamination of polymer solutions, the rinsing steps are normally repeated more than three times and 1 min each at least.…”