Of polyampholytes

Fig. 4. Influence of pH on the plateau-value /T of adsorption isotherms of polyampholytes. At either side of the isoelectric point, i.e.p., the polyampholyte attains a net charge causing intra- and intermolecular electrostatic repulsion. As a result, the mass of adsorbed polyampholyte, that can be accommodated per unit area of the sorbent surface, decreases. Electrostatic interactions are suppressed by increasing ionic strength, yielding /T less sensitive to pH.

Solution prepregging, 20 284-285 Solution processing, 14 80 Solution process, of ethylene-propylene polymer manufacture, 10 708-710 Solution properties of lignin, 15 13 of polyampholytes, 20 479 ofVDC copolymers, 25 703-706 Solution spectrophotometry, 9 232 Solution spinning... 

Investigation of Solution Behavior of Polyampholytes using Gradients. . 95... 

While the bulk behavior of polyampholytes has been investigated for some time now, studies of interfacial performance of polyampholytes are still in their infancy. There are several reasons for the limited amount of experimental work the major one being the rather complex behavior of polyampholytes at interfaces. This complexity stems from a large array of system parameters governing the interaction between the polymer and the substrate. Nearly all interfacial studies on polyampholytes reported to-date involved their adsorption on solid interfaces. For example, Jerome and Stamm and coworkers studied the adsorption of poly(methacryhc acid)-block-poly(dimethyl aminoethyl methacrylate) (PMAA-fc-PDMAEMA) from aqueous solution on sihcon substrates [102,103]. The researchers found that the amount of PMAA-fo-PDMAEMA adsorbed at the solution/substrate interface depended on the solution pH. Specifically, the adsorption increased... 

Tanaka, M., Grosberg, A.Y., Tanaka, T. Molecular dynamics simulations of polyampholytes. Langmuir 1999, 15, 4052-5. 

Collapse of Polyampholyte Gels in Salt-Free Solutions.152... 

Swelling and Collapse of Polyampholyte Networks in the Preseme of Low Molecular Weight Salts... 

The third way to PE-surf nanoparticles is based on the use of polyampholytes, i.e. polyelectrolytes that contain cationic and anionic groups. Examples are long-term stable fluorinated nanoparticles, prepared by the complexation of polyampholytes with perfluorododecanoic acid [131]. The polyampholytes are statistic copolymers of styrylmethyl(trimethyl)ammoni-um chloride, methacrylic acid, and methyl methacrylate having more cationic monomers (28-100 mol %) than anionic monomers (0-16%). The cationic monomers form a complex with perfluorododecanoate ions to create neutral... 

S. Nyret and B. Vincent, The properties of polyampholyte microgel particles prepared by microemulsion polymerization, Polymer 38, 6129-6134 (1997). 

Corpart and Candau [68, 69] described the formulation of polyampholytes containing both positive and negative charges in inverse microemulsions. The copolymers can show very different behaviors in the aqueous solution, ranging from insoluble, water-swollen hydrogels to water-soluble compounds, depending on the monomer composition. For polyampholytes with balanced stoichiometry, the polymer behavior is controlled by attractive electrostatic forces. The compound is usually insoluble in water, but becomes soluble upon the addition of salt. 

Borkovec, M., and G. J. M. Koper. 1994. Affinity distribution of polyampholytes with interacting acid-base groups. Langmuir 10 2863-2865. 

Fig. II. Scheme of polyampholyte - PAA complexes stabilized by ionic and hydrogen bonds 1...

Dependence of the adsorption behavior on the molecular weight has been observed only in the case of polyampholytes of small molecular weight [13]. These polymers show an increase in the adsorbed amount compared to larger polyampholytes, as shown in Fig. 17. This tendency is expected to result from the adsorption of whole micelles of high density. One generally has to consider micelle formation in solution and at the interface to obtain a better understanding of the complex adsorption behavior of polyampholytes. 

Other investigations have been performed where silicon substrates were modified from alkaline to acidic and hydrophobic nature [58], where salt concentration was varied during adsorption [55] and where the nature of one of the blocks was changed [59]. Monolayers of polyampholyte micelles were used to modify protein adsorption [60]. An example is shown in Fig. 18 where the adsorption of fibrinogen is controlled by preadsorption of polyampholyte micelles and the phosphate buffer concentration. 

Fig. 17 Comparison between the maximum adsorbed amount of polyampholyte with two high molecular weights and one low molecular weight as function of the block ratio Mn 65,000 g mol-1, squares Mn=101,000 g mol-1, triangles Mn 14,500 g mol-1, circles...

Fig. 18 Adsorption of the protein fibrinogen as influenced by preadsorption of polyampholyte micelles (PMAA/PDAEMA 33/67 weight ratio, Mn 15,000) in presence of 0.01 mol L-1 (filled symbols) and 0.001 mol L-1 (empty symbols) phosphate buffer solution...

Fig. 30 Capillary isoelectric focussing of polyampholytes PA1-PA4. Separation conditions capillary PVA 40/50 cm, i.d. 75 pm BGE 300 ppm sample in MilliQ+2% Servalyt anolyte H3P04, catholyte NaOH /=+30.0 kV focussing time 12 min mobilization 30 kV+0.1 psi T=25 °C detection at 280 nm...

Note, C., Ruffin, J., Tiersch, B. and Koetz, J. (2007) The influence of polyampholytes on the phase behaviour of microemulsion used as template for the nanoparticle formation. /. Disp. Sci. Tech, 28, 155-164. 

Neyret S, Ouali L, Candau F, Pefferkorn E. Adsorption of polyampholytes on polystyrene latex effect on colloid stability. J Colloid Interface Sci 1995 176 86-94. 

Synthesis and Aqueous Solution Viscosity Behavior of Polyampholytes from Cationic-Anionic Monomer Pairs... 

We investigated the syntheses and viscosity behavior of polyampholytes derived from cationic-anionic monomer pairs of the type shown in Figure 2. It should be noted that the cationic-anionic monomer pairs that are under consideration contain no nonpolymerizable ions. 

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