Controlling the interaction of poly(ethylene imine) adsorption layers with oppositely charged surfactant by tuning the structure of the preadsorbed polyelectrolyte layer

Abstract

This study contributes to the understanding of how the structure of preadsorbed polyelectrolyte layers affects their interaction with oppositely charged surfactants. The adsorbed amount, and thus the adsorption layer structure of poly(ethylene imine), (PEI), was tuned by the pH (4, 6 and 9) of the PEI adsorption. Following the PEI adsorption, each adsorption layer was rinsed with 10 mM NaCl solution (pH Rinse ¼ 6) to establish identical conditions for further SDS binding. The structure of the PEI adsorption layers was investigated in situ by dual polarization interferometry (DPI). By comparing the DPI results with ellipsometry results and by performing DPI and ellipsometry simulations it could be demonstrated the first time that PEI forms a vertically inhomogeneous adsorption layer that can be described as having a compact bottom part, which contains PEI molecules with a large number of surface contacts, and a swollen outer part, which includes loosely bound PEI molecules that extend far into the bulk phase. The pH of the adsorption controls not only the adsorbed mass but also the structure of the adsorbed layer, which can be further tuned by changing the pH of the rinsing solution.To investigate how the structure of the preadsorbed PEI layer affects its interfacial association with SDS, the preadsorbed polymer layers were rinsed with SDS solutions under identical conditions (10 mM NaCl, pH Rinse ¼ 6). It was found that the structure of the preadsorbed PEI layer has a profound effect on the PEI/surfactant interaction. For instance, when the outer part of the PEI layer contained a sufficient amount of polymer segments, desorption of PEI could be prevented. In contrast, when the outer part of the PEI layer was depleted in polymer segments complete desorption could be achieved provided the polymer layer was rinsed with a high concentration ($cmc) surfactant solution under continuous flow.

Polyelectrolyte adsorption, interparticle forces, and colloidal aggregation

“…Numerous optical techniques are available to study the adsorption of PEs to planar solid substrates in real time. 27,79,[91][92][93][94] Let us illustrate the adsorption process of PEs to oppositely charged substrates with reectivity experiments as displayed in Fig. 2a, which allows monitoring of the change in the adsorbed mass per unit area.…”

“…While the differences in the substrates used may lead to these differences, they might also be related to the two sub-layer structure of an adsorbed PE lm. 94 The thickness of these sub-layers may vary upon solution conditions and lead to the different salt dependencies observed with the two different techniques. One should also realize that thickness measurements for such extremely thin lms are difficult and prone to systematic errors.…”

Dual-Polarization Interferometry: A Novel Technique To Light up the Nanomolecular World

“…182 Both surfactant interacted with the poly(2-(dimethylamino)ethyl methacrylate)(50)block-C(60)) layer. For the ethoxylate, the binding occurred by means of pi-pi interactions between the phenyl ring of the TX100 and the C(60) head group.The binding of surfactants to polyelectrolytes was studied by Varga et al by deposition of consecutive films of sodium dodecyl sulfate and poly(ethylene imine) 183.…”

Sensitivity and Response Time of Polyethyleneimine Modified Impedimetric Transducer for Bacteria Detection

“…It was observed that impedance changes were produced quite rapidly reaching saturation in about 20 minutes. Differences between sensors with PEI and PEI‐PSS‐PEI layers most probably may be attributed to a more compact and dense layer in the case of multilayer IDEA surface coating 28.…”