Brush poly electrolyte

Surface force profiles between these polyelectrolyte brush layers have consisted of a long-range electrostatic repulsion and a short-range steric repulsion, as described earlier. Short-range steric repulsion has been analyzed quantitatively to provide the compressibility modulus per unit area (T) of the poly electrolyte brushes as a function of chain density (F) (Fig. 12a). The modulus F decreases linearly with a decrease in the chain density F, and suddenly increases beyond the critical density. The maximum value lies at F = 0.13 chain/nm. When we have decreased the chain density further, the modulus again linearly decreased relative to the chain density, which is natural for chains in the same state. The linear dependence of Y on F in both the low- and the high-density regions indicates that the jump in the compressibility modulus should be correlated with a kind of transition between the two different states. 

The density-dependent jump in the properties of poly electrolyte brushes has also been fonnd in the transfer ratio and the snrface potential of the brnshes [38], establishing the existence of the density (interchain distancej-dependent transition of polyelectrolytes in solntions. 

Double layer interaction between two plates with poly electrolyte brushes... 

Polyelectrolyte brushes are macromolecular monolayers where the chains are attached by one end on the surface and, at the same time, the chains carry a considerable amount of charged groups. Such poly electrolyte structures have received thorough theoretical treatment, and experimental interest has been vast due to the potential of brushes for stabilising colloidal particle dispersions or for... 

Inter-Poly electrolyte and Surfactant Complexes of Cylindrical Polyelectrolyte Brushes... 

Class D. The class of engineered assemblies includes systems that do not spontaneously form ordered structures under normal conditions. Their classification as SPs can be justified since elements of supramolecular interaction stfil assist the final organization. Some examples are layered assembly of complementary poly electrolytes obtained by stepwise deposition under kinetic control (cf. Chapter 19), and polymer brushes prepared by grafting a polymer chain over a SAM of an initiator [6]. Both approaches allow a fine-tuning of surface properties and patterning possibilities. Tailored performance in applications, such as biocompatibility, biocatalysis, integrated optics and electronics have been considered. Additional differences between self-assembled and engineered SPs are discussed in Section I.C. 

Haupt, B., Neumann, T., Wittemann, A., Ballauff, M. (2005). Activity of enzymes immobilized in colloidal spherical poly electrolyte brushes. Biomacromolecules, 6, 948-955. http //dx.doi.org/10.1021/bm0493584. 

The responsiveness of mixed polyelectrolyte brushes is modified by electrostatic interactions which can be used to regulate the mechanism of the phase segregation. Weak mixed poly electrolyte brushes are of special interest since the electrostatic interactions can be affected by pH and ionic strength of aqueous environment and the surface composition of the mixed polyelectrolyte brush can be switched just by a change of external pH. ... 

Ultrafine nanosized magnetic particles can be prepared in situ by using SPB as a nanoreactor (Zhu et al., 2012). Magnetic response is thus induced in SPB. The apphcations of Magnetic spherical poly electrolyte brushes (MSPB), in addition to separation and recycHng, include heat generation (Gelbrich et al., 2010). 

WangX, XuJ, Li L, et al Synthesis of spherical poly electrolyte brushes by thermo-controUed emulsion polymerization, Macromol Rapid Commun 31 1272—1275, 2010. 

Zhu Y, Chen K, Wang X, Guo X Spherical poly electrolyte brushes as a nanoreactor for synthesis of ultrafine magnetic nanoparticles. Nanotechnology 23 265601-1—265601-9, 2012. Zhulina EB, Borisov OV Poly electrolytes grafted to curved surfaces. Macromolecules 29 2618-2626, 1996. 

Poly(ionic liquid) brushes with terminated ferrocene units acted similarly, while the interfacial resistance was probed by hexacyanoferrate [457]. Chemical and electrochemical switching of local pH at an electrode-grafted poly(vinyl pyridine) brush again allowed modulation of hexacyanoferrate chemistiy (Fig. 43) [458]. Octacyanomolybdate was used as catalyst for the oxidation of ascorbic acid [459]. Even heteropolyanions (Keggin ions) could be entrapped in polymer films electrochemicaUy [460]. Further, thermoresponsive or pH-responsive cationic copolymer films modulated the hexacyanoferrate or ferrocenedicarboxyUc acid electrochemistry by temperature or variatimi of pH and perchlorate concentration, respectively [461-463]. Besides these complexes with cationic polyelectrolyte films, electroactive cationic counterions (e.g., the europium couple) interacted with anionic networks [464]. Similarly, copper ions within a PAA matrix [367] allowed the construction of actuators [465]. Besides these binary systems (poly-electrolyte/electroactive counterions), multiresponsive electrode modification with an interpenetrating gel network of poly(acrylic) acid and poly(diethyl acrylamide) allowed the modulation of hexacyanoferrate electrochemistry [368]. 

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