NMR Studies of the Effect of Adsorbed Water on Polyelectrolyte Multilayer Films in the Solid State (original) (raw)
Related papers
NMR Studies of PAH/PSS Polyelectrolyte Multilayers Adsorbed onto Silica
Macromolecules, 2004
Solid-state NMR spectroscopy is used to monitor the layer-by-layer (L-B-L) growth of polyelectrolyte multilayers on colloidal silica. The dynamics and conformation of polyelectrolyte multilayers comprised of the weak polycation, poly(allylamine) hydrochloride, and the strong polyanion, poly(sodium-4-styrene sulfonate), assembled at pH 7 and pH 10 were studied by a combination of 1 H and 13 C NMR measurements. NOESY spectra detect the association of water to the polyanion, while relaxation measurements show that the outermost layer and the water content influence the mobility of the polyelectrolytes and the adsorbed water. Differences in mobility for films assembled at high and neutral pH are explained by the conformation of the polycation during the assembly process. Finally, the strongweak polyelectrolyte multilayers are compared to a previous NMR study of strong-strong polyelectrolyte multilayers.
13 C Solid-State NMR Study of Polyelectrolyte Multilayers
Macromolecules, 2003
Polyelectrolyte multilayers have been prepared by consecutively adsorbing poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) from aqueous solution onto colloidal silica (70-100 nm in diameter), with a total of five bilayers being prepared. The multilayer growth was followed by electrophoretic mobility as well as solid-state NMR spectroscopy. The electophoretic mobility measurements show the expected reversal in the -potential with the alternate adsorption of the polycation and polyanion. The alternation in the relative intensities observed in the 13 C solid-state NMR spectra was used to qualitatively follow the layer-by-layer growth. Relaxation measurements show that the mobility of the polyanion is found to remain constant throughout the layer-by-layer assembly, while the mobility of polycation decreases with increasing numbers of layers.
The Journal of Physical Chemistry B, 2007
With X-ray and neutron reflectivity, the structure and composition of polyelectrolyte multilayers from poly-(allyl amine) (PAH) and poly(styrene sulfonate) (PSS) are studied as function of preparation conditions (salt concentration and solution temperature, T). The onset of a temperature effect occurs at 0.05 M NaCl (Debye length ∼ 1 nm). At 1 M salt, the film thickness increases by a factor of 3 on heating the deposition solution from 5 to 60°C. The PAH/PSS bilayer thickness is independent of the kind of salt (NaCl or KCl), yet its composition is different (more bound water for NaCl). At low T, the internal roughness is 33% of the bilayer thickness; it increases to 60% at high T. The roughening is accompanied by a total loss of bound water. At which temperature the roughening starts is a function of the kind of salt (50°C for NaCl and 35°C for KCl). The strong temperature dependence and the eventual loss of bound water molecules may be attributed to the hydrophobic force; however, there is an isotope effect, since the loss of bound water is less pronounced in the deuterated layers. † Part of the special issue "International Symposium on Polyelectrolytes (2006)".
Physical Chemistry Chemical Physics, 2006
As-deposited films of multilayered polyelectrolytes are considered to be non-equilibrium structures. Due to the strong attraction between oppositely charged polyions, polyelectrolyte interdiffusion is thought to be suppressed during the adsorption process. Equilibration is promoted by a decrease of the electrostatic attraction between polyion pairs. We have used neutral impact collision ion scattering spectroscopy to investigate the influence of polyelectrolyte multilayer annealing in water and aqueous 1 M NaCl solutions at different temperatures (20 and 70 1C) on the increase in interpenetration of a single polyelectrolyte layer throughout the whole film. The multilayers were composed of poly(4-vinylpyridinium) and poly(4-styrenesulfonate). Contrast between neighboring layers was established by labelling the layer in question with the heavy atom ruthenium. It is found that both temperature and salt increase layer interpenetration, whereas salt has a stronger influence than temperature. From numerical simulations polyelectrolyte diffusion coefficients were evaluated for the different annealing conditions. The influence of temperature and salt on the equilibration of the film is interpreted in terms of increased screening of polyion charges and binding of small counterions to polyion monomeric units.
Langmuir, 2008
The alternate adsorption of polycation poly(allylamine hydrochloride)(PAH) and the sodium salt of the polymeric dye poly{1-[p-(3′-carboxy-4′-hydroxyphenylazo)benzenesulfonamido]-1,2-ethandiyl}(PCBS) on quartz crystals coated with silica was studied to understand the structural properties and adsorption kinetics of these films using a combination of quartz crystal microbalance with dissipation monitoring (QCM-D), absorbance, and ellipsometry measurements. In-situ deposition of the polycation PAH on QCM crystals was monitored, followed by rinsing with water and then deposition of the polyanion PCBS. The effects of polymer concentration and pH on film structure, composition and adsorption kinetics were probed. The polymers were adsorbed at neutral pH conditions and at elevated pH conditions where PAH was essentially uncharged to obtain much thicker films. The change in the resonant frequency, ∆f, of the QCM-D showed a linear decrease with the number of bilayers, a finding consistent with absorbance and ellipsometric thickness measurements which showed linear growth of film thickness. By using the ∆f ratios of PCBS to PAH, the molar ratios of repeat units of PCBS to PAH in the bilayer films as determined by QCM-D were ∼1:1 at polyelectrolyte concentrations 5-10 mM repeat unit, indicating complete dissociation of the ionic groups. The frequency and dissipation data from the QCM-D experiments were analyzed with the Voigt model to estimate the thickness of the hydrated films which were then compared with thicknesses of dry films measured by ellipsometry. This led to estimates of the water content of the films to be ∼45 wt %. In addition to the QCM-D, some films were also characterized by a QCM which measures only the first harmonic without dissipation monitoring. For the deposition conditions studied, the deposited mass values measured by the QCM's first harmonic were similar to the results obtained using higher harmonics from QCM-D, indicating that the self-assembled polyelectrolyte films were rigid.
Polymer chain mobility in polyelectrolyte multilayers
Polymer Science, Series C, 2017
Free-standing polyelectrolyte multilayer membranes have been formed by the layer-by-layer technique using a dip-coating apparatus. The polymer-chain mobility has been studied by 1 H relaxation in the rotating frame T 1rho NMR with 13 C chemical shift resolution. For each of the individual polymers a single relaxation component has been observed for all resolved signals. In the multilayer a significantly different relaxation time T 1rho has been observed with a minor second component. The interaction between the oppositely charged polyelectrolytes influences the molecular mobility.
Polyelectrolyte Multilayers Studied by Electron Paramagnetic Resonance (EPR) Spin-Label Technique
Applied Magnetic Resonance, 2013
A nitroxide spin label has been covalently attached to the polyelectrolyte poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the interaction between this weak polyanion, the oppositely charged strong polycation poly(diallyldimethylammonium chloride) (PDADMAC) and water in swollen polyelectrolyte multilayers (PEM) by electron paramagnetic resonance (EPR) spectroscopy. If the spin-labeled polyanion has been used for the preparation of every double layer, the growth of the PEM film can be monitored by quantitative EPR. On the other hand, if the spin-labeled polyanion has been selectively placed in different layers in the PEM film the influence of the environment such as pH of the swelling medium of the mobility of the polyelectrolyte molecules positioned in the selected layer can be investigated.
We study the static and dynamic properties of water near a poly(styrene sulfonate)/ poly(diallyldimethylammonium) (PSS/PDADMA) bilayer adsorbed onto a substrate by atomistic molecular dynamics simulations. Qualitative changes in the dynamics of water in the proximity of the adsorbed bilayer are observed -such as in the lateral diffusion, residence time and hydrogenbonding lifetime -as compared with water in the presence of the bare substrate. Static properties of water are similarly influenced, and a high polarization of water molecules is found to be present surprisingly far from the adsorbed bilayer.
Hydration and internal properties of polyelectrolyte multilayers
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
In this review we summarize novel aspects of the hydration and internal properties of polyelectrolyte multilayers formed by layer-by-layer assembly. Reflectivity techniques monitor the water content and swelling behavior, while spin relaxation monitors water mobility. Odd-even effects in dependence on the number of layers are discussed in terms of an influence of the terminating layer. Other novel methodological approaches like X-ray microscopy or NMR cryoporometry address the water content in hollow capsules, and the water pore size distribution, respectively. Multilayer material properties are relevant for different applications. As a novel concept, dielectric properties are monitored in a field effect transistor device. Ion mobility and redox processes in multilayers are revealed by the electrochemical properties. Mechanical properties of multilayers, studied by colloidal probe atomic force microscopy depend on the conformation of the polymers involved.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011
a b s t r a c t X-ray reflectivity and adsorption kinetics of two different polyelectrolyte multilayers have been studied for polyelectrolyte multilayers (PEMs) composed of poly(diallyldimethyl ammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) polyelectrolyte pair and of poly(allylamine hydrochloride) (PAH) and PSS. The two characteristic times that describe the adsorption kinetics were found to be related to the X-ray reflectivity results, and their dependence on the number of adsorbed layers depends on the growth mechanisms (linear or superlinear) of the films. Therefore, it has been concluded that there is a correlation between the adsorption kinetics and the internal structure of the films. The time allowed for the adsorption of each polyelectrolyte controls the extension of the interdiffusion within the multilayer, and therefore whether the film is formed by stratified layers or it has a uniform structure except for the first and last layers. While the roughness of the (PDADMAC + PSS) n films strongly depends on the adsorption time, it is almost independent of it for the (PAH + PSS) n multilayer. This behavior correlates with that of the longest characteristic time of the adsorption kinetics.