Polyelectrolyte complexes for surface modification of wood fibres (original) (raw)
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Polyelectrolyte swelling behavior of chlorite delignified spruce wood fibers
Wood Science and Technology, 1983
A coarse thermomechanical Asplund pulp was prepared from Norway spruce (Picea abies). The pulp was delignified to different degrees using acidified sodium chlorite. The swelling behavior (measured as water retention value = WRV) of the resulting pulps was studied under various chemical conditions (pH and conc. of NaC1). It is shown that chloritedelignified pulps have an appreciable polyelectrolytic character. Whereas the WRV of an Asplund pulp does not respond to changes in the chemical environment, the delignified pulp has a WRV of 155 at pH 3 and 250 at pH 9. Compared under the same chemical conditions, the WRV increases with increasing degree of delignification < 70%) and is approximately constant at high degrees ofdelignification (> 70%).
Carbohydrate Polymers, 2015
In this work, polyelectrolyte complexes (PECs) were formed by adding polyacrylic acid (PAA) or 4-O-methylglucuronoxylan (Xyl) on poly(allylamine hydrochloride) (PAH) solutions, at different ionic strength and neutral pH. Turbidity curves, charge densities of the cationic complexes determined by polyelectrolyte titration method, and z-potential values showed clear differences between both complexes. Stirring favourably reverses the effects of sedimentation of Xyl/PAH complexes, as demonstrated by colloidal stability tests. Adsorption studies on silica surfaces, performed by Quartz Crystal Microbalance with Dissipation (QCM-D) showed that PAA/PAH adsorbed complexes layers were rigid, while the corresponding Xyl/PAH layers were viscoelastic. Despite the different conformations, both complexes were adsorbed as spherical particles, as observed by Atomic Force
Growth of Polyelectrolyte on Lignocellulosic Fibres: Study by Zeta Potential, Ftir, and XPS
BioResources, 2012
A layer-by-layer (LbL) self-assembly technique using polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) was employed to build up polyelectrolyte multi-layers on pretreated thermomechanical pulp fibres. These pretreated fibres previously had been oxidized by means of a 4-acetamido TEMPO-mediated process in order to create carboxylic functions. These allow the subsequent formation of amide bonds between PAH and fibres. X-ray photo-electronic spectroscopy (XPS) analyses confirmed the formation of amide bonds between the carboxylic function on the fibres and the primary amine function of the PAH. Besides, the surface charge intensity of the coated fibres was determined by measuring the zeta potential after each treatment step.
BioResources, 2013
The charge density of a bleached Kraft hardwood pulp, subjected to layer-by-layer adsorption of the oppositely charged cellulose derivative polyelectrolytes hydroxyethylcellulose ethoxylate, quaternised (HECE), and carboxymethyl cellulose (CMC), was studied by polyelectrolyte titration as a function of pH and ionic strength. The experimental design included a simultaneous variation of the experimental parameters, and the trends were evaluated with the help of partial least squares regression. As expected from the literature, the data indicate that both pH and ionic strength influence the charge of cationic fibers. It is also obvious that CMC as an outermost layer is more sensitive to changes in pH than the deprotonation of ≡COOH groups suggests. High ionic strength seems to be beneficial for the adsorption of HECE, while the pH dependence seems much more complicated. The non-linear pH dependence indicates that, in addition to electrostatic interactions, entropy factors and hydrogen bonding between OH groups on both the substrates and ligands are responsible for the adsorption, which is in agreement with literature on the subject.
European Polymer Journal, 2001
The eects of NaCl, NaI and Na 2 SO 4 on the formation of polyelectrolyte complex (PEC) between a polycation with N,N-dimethyl-2-hydroxypropyleneammonium chloride units in the main chain (PCA 5) and poly(sodium acrylate) (NaPA) were studied. The NaCl concentration in the polyelectrolyte solutions ranged from 0 to 2 M. Viscometric and turbidimetric measurements were used to follow the eect of the salt concentration and of the counterion nature on the PEC formation. The in¯uence of counterions was dierent depending on both the radius of the hydrated ion and its valence. At the same concentration of the low-molecular-weight salt, the following order of the PEC separation in dependence on the counterion was evidenced: R sep SO 2À 4 < R sep I À < R sep Cl À. The critical concentration of NaCl for this system was established.
Langmuir : the ACS journal of surfaces and colloids, 2017
To clarify the importance of the surface charge for the formation of polyelectrolyte multilayers, layer-by-layer (LbL) assemblies of polydiallyldimethylammonium chloride (pDADMAC) and polystyrenesulfonate (PSS) have been investigated on cellulose films with different carboxylic acid contents (20, 350, 870, and 1200 μmol/g) regenerated from oxidized cellulose. The wet cellulose films were thoroughly characterized prior to multilayer deposition using quantitative nanomechanical mapping (QNM), which showed that the mechanical properties were greatly affected by the degree of oxidation of the cellulose. Atomic force microscopy (AFM) force measurements were used to determine the surface potential of the cellulose films by fitting the force data to the DLVO theory. With the exception of the 1200 μmol/g film, the force measurements showed a second-order polynomial increase in surface potential with increasing degree of oxidation. The low surface potential for the 1200 μmol/g film was attri...
Journal of Polymer Science Part A: Polymer Chemistry, 2007
Polyelectrolyte complexes between poly(methacrylic acid, sodium salt) and poly(diallyldimethylammonium chloride) (PDADMAC) or poly [2-(methacryloyloxyethyl)trimethylammonium chloride] (PMOETAC) form gels, liquid phases, or soluble complexes depending on charge ratio, total polymer loading, polymer molecular weight, and ionic strength. Increasing the ionic strength of the medium led most polyelectrolyte pairs to transition from gel through liquid complexes (complex coacervate) to soluble complexes. These transitions shift to higher ionic strengths for higher molecular weight polymers, as well as for PMOETAC compared to PDADMAC. The complex phases swelled with increasing polymer loading, ultimately merging with the supernatant phase at a critical polymer loading. The isolated liquid complex phases below and above this critical loading were temperaturesensitive, showing cloud points followed by macroscopic phase separation upon heating. Incorporating 5 mol % lauryl methacrylate into the polyanion led to increased complex yield with PDADMAC, and increased resistance to ionic strength. In contrast, incorporating 30 mol % of oligo(ethylene glycol) methacrylate into the polyanion led to decreased complex yield, and to lower resistance to ionic strength. Two polyelectrolyte systems that produced liquid complexes were used to encapsulate hydrophobic oils, and in one case were used to demonstrate the feasibility of crosslinking the resulting capsule walls. V V C 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4129-4143, 2007
Journal of Colloid and Interface Science, 2010
In this work, the formation of polyelectrolyte complexes (PECs) has been studied using a jet mixing method not previously used for mixing polyelectrolytes. The PECs were formed from two weak polyelectrolytes, i.e., polyacrylic acid (PAA) and polyallylamine hydrochloride (PAH), with different mixing times, and the results were compared with those for PECs formed using the conventional polyelectrolyte titration method. The adsorption behaviour of the formed PECs on silicon oxide substrates and pulp fibres was analysed, and the results were compared with those for polyelectrolyte multilayers (PEMs) prepared from the same two polyelectrolytes. The results indicated that by using the jet mixer, the size of the formed PECs could be controlled, which was not the case with the polyelectrolyte titration method. The PECs produced by jet mixing were also found to be smaller than those produced by polyelectrolyte titration. From these results, a two-step mechanism for the formation of PECs was suggested: initial precomplex formation, which is a fast and diffusion-controlled process, followed by a reconformation process, during which the vigorous mixing in the jet mixer can partially limit secondary aggregation. When the complexes were adsorbed to silicon oxide or pulp fibre surfaces, adsorption studies indicated that it was impossible to reach the same adsorption levels for PECs as for PEMs. This was explained in terms of free energy, entropical, reasons rather than to any geometric limitation of the surface. Despite the smaller amount of polyelectrolyte adsorbed from the PEC treatment than from the PEM treatment of pulp fibres, the PEC treatment had the greatest effect on paper strength per adsorbed amount of polymer. This was thought to be because the three-dimensional structure of the PECs, versus the smoother structure of PEMs, allows for the formation of multiple contact points between the macroscopically rough fibres and increased molecular contact area.