Use of Pulsed Streaming Potential with a Prepared Cationic Polyelectrolyte Layer to Detect Deposition Kinetics of Graphene Oxide and Consequences of Particle Size Differences

Abstract

The deposition kinetics of graphene oxide (GO) onto poly(ethylene imine) (PEI) layer was characterized in situ with pulsed streaming potential (SP) measurement, and it was found that the initial rate constant (k) was dependent on the size of GO with same surface charge density at a fixed concentration under controlled experimental conditions. Assuming the deposition was controlled by diffusion at the initial stage, k is proportional to R, where R is the hydrodynamic radius. By flushing a GO solution through a capillary coated with PEI, the initial change rate of relative SP (dE/dt) was obtained in 20 s and k was measured with five different concentrations in about 2 min. Three GO samples of different sizes obtained from the same batch of raw material were characterized with pulsed SP to get k values, and their sizes were verified with atomic force microscopy and dynamic light scattering. The experimental results are consistent with the predicted effects of the size of NPs on their deposition kinetics.

Conformations of Poly-l-lysine Molecules in Electrolyte Solutions: Modeling and Experimental Measurements

“…Therefore, the results shown in Table indicate that even for the high ionic strength up to 0.15 M, PLL molecules assume an elongated shape characterized by the length to width ratio exceeding 43. These data have significance for interpreting PLL adsorption on various surfaces, which is often used for creating supporting layers for particle deposition, ,− protein immobilization, ,− and for producing macroion films in the LbL processes. − …”

“…These data have significance for interpreting PLL adsorption at various surfaces, which is often used for creating supporting layers for deposition, 30,[72][73][74] protein immobilization, 11,[75][76][77][78] and for producing macroion films in the layer-by-layer processes. [79][80][81][82] Another aspect of practical significance is that the intrinsic viscosity data can be used for the determination of the molar mass of macroions samples with a precision exceeding other conventional techniques.…”

Deciphering the Dynamic Assembling–Disassembling of Small Molecules on Solid/Liquid Interfaces within Microchannels by Pulsed Streaming Potential Measurement

“…This technique has been employed to real-time monitor the adsorption kinetics of lysozymes onto plastic microchannel surfaces . Pulsed SP measurement has also enabled the real-time monitoring of the dynamics of self-assembly of polyelectrolytes, the adsorption of proteins and nanoparticles. , In the case of cationic small molecules, that possess a positive surface charge in the buffer, the surface charge of the silica capillary changes from negative to positive during their assembling. , This observation suggests that pulsed SP measurement can be used to monitor the assembly of cationic small molecules by tracking the alternations in surface charge within a microchannel.…”