Growth Kinetics in Layer‐by‐Layer Assemblies of Organic Nanoparticles and Polyelectrolytes

Abstract

The growth rates of layer-by-layer (LbL) assemblies of polyelectrolytes (PEs) with oppositely charged polystyrene (PS) nanoparticles (NPs) as a function of molecular weight (MW) of the PEs, ionic strength of the media, and NP size and charge are systematically investigated. To optimize LbL growth, the effects of suspension concentration, pH of the media, and deposition time on the growth rate of multilayers are assessed. Both linear and exponential growth behaviors are observed and, under optimal conditions, films of up to around 1 μm thick can readily be assembled after 10 or so bilayers have been deposited. For many of the cases studied, an intermediate MW of PE leads to the fastest film buildup, for both cationic poly(ethyleneimine) deposited alternately with anionic PS NPs and for anionic poly(acrylic acid) deposited alternately with cationic PS NPs. The existence of an optimal MW suggests that growth rate is determined by a balance of thermodynamic factors, including density of polymer bridges between particles, and kinetic factors, specifically the diffusivity of polymer in the film. The optimal MW, however, is very sensitive to the materials used. Moreover, depending on the MW of the PE, increasing salinity could increase or decrease the growth kinetics. Finally, the surface morphology of the films is characterized with AFM and SEM to reveal that the roughness increases less than linearly with film thickness.

Electrochemical Response of Clay/Polyelectrolyte Composite Barrier Coatings

“…The thickness increased as n increased: at n = 5, the thickness per bilayer (BL) was small (20 nm/BL), but, after that, the thickness per bilayer increased to more than 50 nm/BL. This growth rate is much higher than that of the previously reported LbL MMT-PEI coating (3 nm/BL) [6], possibly because of the differences of the PEI molecular weight and the substrates used (i.e., poly(ethylene terephthalate) vs. gold) [10]. It should be noted that the thickness of LbL (MMT-PEI) n was hardly affected by the pH of the MMT dispersion solution.…”

Modulating the Kinetics of Nanoparticle Adsorption for Simple and High‐Yield Fabrication of Plasmonic Heterostructures as SERS Substrates

“…QCM presents a highly suitable platform for such experiments. QCM relies on the shift of the resonant frequency of an oscillating piezoelectric quartz crystal upon the adsorption of a mass . The key advantages of this technique lie in the nanogram level sensitivity in the measurement of the adsorbed mass and real‐time monitoring of the adsorption processes.…”

“…QCM relies on the shifto ft he resonant frequency of an oscillating piezoelectric quartz crystal upon the adsorption of am ass. [26][27][28] The key advantages of this technique lie in the nanogramlevel sensitivity in the measurement of the adsorbed mass and real-time monitoring of the adsorption processes. QCMw ith dissipation monitoring (QCM-D) provides additional information about the viscoelastic character of the mass adsorptionf rom the liquid phase.…”

Layer-by-Layer Deposition: A Promising Environmentally Benign Flame-Retardant Treatment for Cotton, Polyester, Polyamide and Blended Textiles

“…Factors influencing the reproducible results are longer adsorption time and rinsing volume to avoid the cross-contamination of deposition solutions (dilution factor should be at least 1:106), as well as surface coverage of functional groups [22]. Parameters influencing the growth kinetics of LbL assembly include the type of polyelectrolytes, their molecular weights and concentrations in solutions, the pH of solutions, addition of low-molecular-weight additives or salts, additional sonication of the solutions, adsorption time and rinsing solutions [33][34][35][36]. Larger polyelectrolytes form slightly thicker coatings and require longer deposition times, while smaller molecules show strong dip time-dependent thickness of the LbL assembly [37].…”