Macromolecular polymer concentration

On the other hand, two important factors of macromolecular chain reactivity in solution deserve more attention,namely the nature of the reaction medium and the polymer concentration. 

The Al3+ ion shows a propensity to suffer hydrolysis which can produce the formation of various mononuclear hydroxo complexes. At pH around 7.0 it often precipitates as Al(OH)3, which redissolves leading to the formation of aluminate, Al(OH)4. After this, polynuclear complexes such as Al2(OH)2, Al3(OH)4] and Al13(OH)32 can also form. These species can produce, in a very slow process, oligomeric complexes, which are necessary precursors of the macromolecular polymer [Al(OH)3]n [16, 17]. In Fig. 2 we can observe the distribution of the Al3+ aquo ion and the species for 100 mM and 10 pM total aluminum. The maximum concentration of Al(OH)3 is reached at about neutral pH. At pH > 7.0 the predominant species is aluminate ion A OH). ... 

The three-dimensional plot [57] of as a function of salt and polymer concentrations for cyclocopolymers consisting of sulfobetaine and cationic monomers shows that the value of R passes through a minimum at any polymer concentration as the ionic strength of the medium is increased. The initial decrease of R is attributed to the screening of electrostatic repulsions between positive charges by small ions. The minimum R corresponds to the collapsed state of the polymer chain. The reexpansion of the macromolecular chain with increasing ionic strength is due to the suppression of intramolecular dipole-dipole interactions between the sulfobetaine mer imits. 

The membrane performance was good, during almost 60-h operation and the permeate flux was stable after initial decline. The biggest flux decrease was observed when macromolecular sodium polyacrylate was introduced first after dosing 0.4 g/L of NaPAA, then after injection of the next portion (1 g/L NaPAA). In that time, permeate flux declined from 52 L/m h in the beginning (without the complexing agent), to 11 L/m h after injection of 1 g/L of the polymer. Further increase of polymer concentration did not result in the flux decline, as well as addition of CoCF suspension. 

For all cellulose derivatives tested, a reduction of the zeta potential of the suspensions with increased polymer concentration is observed (Table 20). The effect of the molecular mass differs depending on the derivative concerned. For HEC and HPC, the amount adsorbed and the area per molecule decreased as the molecular mass increased, indicating a flatter adsorption conformation. For HPMC, the adsorption increased as the macromolecular chains became longer. Adsorption was maximum for the more hydrophobic HPC. 

Macromolecular colloid solutions also play an important role in ensuring the stability of disperse systems (e.g. suspensions, emulsions). In the case of emulsions the polymer decreases the rate of separation by increasing viscosity on the one hand, and it has an enthalpy stabilizing effect by adsorption on the surface of the droplets on the other hand [3, 4, 7]. Depending on the concentration of the polymer, a protecting and flocculating effect can be observed during the interaction between suspensions and polymers. If the polymer concentration is low, the polymer adsorbed on the surface of the particles connects the particles into loose floccules. Thereby, the rate of... 

The increase of phosphatides removal degree Q up to some polymer flocculator concentration at which the greatest value Q (Q ) is reached, is due to a simple increase of active centers (capture sites [183]) number of flocculation owing to a macromolecular coils (polymer concentration) number growth in solution. At the concentration macromolecular coils touching occurs, that corresponds to At growth coils interpenetration is realized and the indicated transition scale is determined by the criterion [131] ... 

Miktoaim stars consisting of one thermoresponsive PNIPAAM arm and four pH-responsive PDMAEMA arms were synthesized and their micellization behavior in aqueous solutions was compared with the corresponding linear PNIPAAM-b-PDMAEMA block copolymers.PNIPAAM-core micelles were obtained in acidic solutions at elevated temperatures, whereas PDMAEMA-core micelles were formed in slightly alkaline solutions at room temperature. Furthermore, the kinetics of pH-induced micellization of the AB4 miktoarm stars and the linear block copolymers was studied by the stopped-flow LS technique upon a pH jump from 4 to 10. The data of both types of copolymers could be fitted with double-exponential functions yielding a fast (xj) and a slow (T2) relaxation process. For both copolymers xj decreased with increasing polymer concentration. However, xj was independent of polymer concentration for the AB4 stars, whereas it decreased with increasing polymer concentration for the linear block copolymer. This result indicates that the macromolecular architecture may greatly influence the kinetics of micellization. 

As long as the polymer concentration in solution remains low, this phenomenon has little effect on the stability of the suspension. However, gradually adding more polymer to the medium results in a supersaturation in the interparticle region, whilst the sheath surrounding each particle is depleted in the macromolecular species (see Fig. 3.17a). An effective way to combat this su-... 

Fluorescence-labeled polymer chains have been investigated by FCS to determine macromolecular diffusion in different polymer concentration regimes. Most studies were performed on labeled PS chains in toluene solutimis of non-labeled PS of similar length. 

The presence of a sharply defined interface between a polymer solution and a solid wall leads to important modifications in the local polymer concentration with respect to the bulk concentration. These variations can be positive or negative depending on the sign of the interaction between the solid wall and the macromolecular chains immersed in the solvent. Attractive forces lead to adsorbed layers while repulsive forces lead to depletion layers. Due to their connection with important technological applications such as adhesives, protective coatings, microlithography, emulsion stabilizers, adsorbed polymer layers have been the subject of extensive theoretical studies. ... 

Technology, Ph.D. Plastics Engineering Option B.S., M.S., Ph.D. Chemical Engineering (Polymer Option) M.S., Ph.D. Polymer Science and Engineering M.S., Ph.D. Macromolecular Science and Engineering B.S., M.S., Ph.D. Chemical Engineering and Materials Science (Polymer Concentration)... 

Diffusion theory involves the interdiffusion of macromolecules between the adhesive and the substrate across the interface. The original interface becomes an interphase composed of mixtures of the two polymer materials. The chemical composition of the interphase becomes complex due to the development of concentration gradients. Such a macromolecular interdiffusion process is only... 

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