Aqueous solution behavior

The purpose of this study was to prepare a series of random copolymers of NIPAAM with predictable and well defined temperatures of precipitation covering the range of 0 to 45 C, as well as some that precipitate above 55 C under the conditions of high salt used in DNA hybridization assays. The N-substituted acrylfiunides offer the greatest chemical similarity to NIPAAM and therefore should copolymerize randomly with the latter ( ). Thus, copolymers of NIPAAM with AAM, NMAAM, NEAAM, NNBAAM and NTBAAM were prepared at selected monomer ratios and their aqueous solution behavior was evaluated. 

S. A. Leharne, E. Eagland, and N. J. Crowther. 1994. An investigation of dilute aqueous solution behavior of poly(oxyethylene )poly(oxypropylene)-poly(oxyethylene) block copolymerlsangmuir 10 4001—4005. 

The 13C-NMR spectral analysis of ajaconine in nonionic and ionic solvents indicated that in hydroxylic solvents the ether linkage of ajaconine ionizes and covalent solvation takes place (87). This observation accounted for the formation of the Schiff salt, with the resultant high pA a value (11.8) of ajaconine in aqueous solution—behavior which parallels that of atisine (pKa 12.5) and veatchine (pA a 11.5). These results suggested that ajaconine may be rearranged by refluxing in an ionic solvent to a compound in which the C-7-C-20 ether linkage is absent. 

Aqueous carbonate complexes of An ions, An(C03) ", =1—5, form stepwise with increasing solution pH and carbonate concentration." As with other oxoanionic ligand systems, the stability of the carbonate complexes decreases across the series, such that the pentacarbonato complex is well studied for Th and U. The tetracarbonato complex is more important for Np and Pu in solution, although salts of the pentacarbonato anion are known across the series. Most studies of Th, U, Np, and Pu do indicate that mixed hydroxyocarbonate complexes, An(0H) t(C03) " " e.g, Th(0H)3(C03) for Th, are important in describing the aqueous solution behavior. For the lower order carbonates the actinide is presumably nine or ten-coordinate with waters and bidentate carbonate in the inner coordination sphere. For the penta-and hexacarbonato complexes there is no evidence that any water molecules remain bound to the actinide center. 

When dissolved in aqueous solutions of diverse ions potassium Kurrol s salt is a viscous solution at concentration of 1% polyphosphate. The cross-linked Kurrol s is even more viscous and exhibits a stringiness not seen in the Kurrol s salts prepared with K O-P2O5 ratios equal to unity. The aqueous solution behavior of cross-linked Kurrol s salt may be caused by the a second phase of the system superimposed upon the viscous behavior of the solutions of 1.0 K2O-P2O5 ratio potassium Kurrol s salt solutions. 

Polyelectrolyte solutions have been investigated much more extensively in aqueous solutions than in nonaqueous solutions [1-5]. Since many polyelectrolytes, usually with high charge density, are difficult to dissolve in polar organic solvents, and since there is a great interest in biological polyelectrolytes [6-8] such as proteins, nucleic acids, and polysaccharides in aqueous solutions, the aqueous solution behavior of polyelectrolytes has become a main subject of study. 

Wang TK, Iliopoulos I, Audebert R. Aqueous solution behavior of hydrophobically modified poly(acrylic acid). In Shalaby SW, McCormick C, Butler GB, eds. Water-Soluble Polymers Synthesis, Solution Properties, and Applications. ACS Symposium Series 467, 1991 218-231. 

The lack of a backbone methyl group (which is present in PMAA) has a profound effect on the aqueous solution behavior of PAA potentiometric [3,4,47,49] and... 

Changes in the fluorescence spectral characteristics of water-soluble probes have also been used to provide information concerning the aqueous solution behavior of PAA [72-75,77], For example, the fluorescence intensity of AuO is low in water but is enhanced in the presence of PMAA, particularly at low degrees of ionization [52,73]. This enhancement was attributed to a higher local viscosity at the molecular level created by the polyelectrolyte chains. The emission from AuO dispersed in PAA, on the other hand, was low across the complete pH range [73] and implies that the probe resides in a water-rich phase, which is consistent with an expanded polymer conformation. 

J2.5 Excimer Formation The short-range nature (ca. 2 nm) of the interaction between a ground-state chromophore and an excited state species during excimer formation has been exploited by researchers to monitor the aqueous solution behavior of PAA [23,87,120-122],... 

To calculate gas solubility in natural geochemical systems, basic thermodynamic properties such as the Henry s law constant and, in the case of weak electrolytes the dissociation constant, must be combined with a thermodynamic model of aqueous solution behavior. An analogous approach has been used to predict mineral solubilities in concentrated brines (1). Such systems are also relevant to the atmosphere where very concentrated solutions occur as micrometer sized aerosol particles and droplets, which contain very small amounts of water relative to the surrounding gas phase. The ambient relative humidity (RH) controls solute concentrations in the droplets, which will be very dilute near 1(X)% RH, but become supersaturated with respect to soluble constituents (such as NaCl) below about 75% RH. The chemistry of the aerosol is complicated by the non-ideality inherent in concentrated electrolyte solutions. 

The reactions of water, H+, OH , and O2- describe the aqueous solution behavior of many cations—alkali, alkaline earth, Al, and others. This is Broristed acid-base... 

TIE Tiera, M.J., Santos, G.R. dos, Oliveira Tiera, V.A. de, Vieira, N.A.B., Frolini, E., Silva, R.C. da, and Loh, W., Aqueous solution behavior of thermosensitive (N-isopropylaciylamide-acrylic acid-ethyl methacrylate) terpolymers, Coll. Polym. Sci., 283, 662, 2005. 

As for the HNO-complexes, all the available evidence in nonaqueous and aqueous media suggest that these species are inert with respect to HNO-dissociation (the trans-effect is negUgible). A recent revision of the aqueous solution behavior of [Fe(CN)sHNO] shows that its main absorption band at 445 nm decays very slowly at pH 6, through an oxidation process of HNO leading mainly to [Fe(CN)sNO] , with fedecomp... 

Diamond RM (1963) The aqueous solution behavior of large univalwent ions a new type of ion pairing. J Phys Chem 67 2513-2517... 

In this chapter recent developments in the field of DHBCs are described. Excellent review articles have already outlined the major features of DHBCs [1,2]. A number of exeellent reviews summarize speeific aspects of DHBCs in detail [3,4,5]. This chapter is focused on recent advances in the particular research area. The synthetic strategies followed for the preparation of DHBCs, important investigations on their aqueous solution behavior and a number of potential applications are presented. The field is growing rapidly. Therefore, the creation of a complete list of works, concerning DHBCs, is practically impossible and beyond the goal of this chapter. The works presented here have been selected in order to representatively describe the current developments in DHBC research. 

HOU Housni, A. and Narain, R., Aqueous solution behavior of poly(A-isopropyl acrylamide) in the presence of water-soluble macromolecular species, Eur. Polym. J., 43, 4344,2007. 

ROT Rotureau, E., Chassenieux, C., Dellacherie, E., and Durand, A., Neutral polymeric surfactants derived from dextran A study of their aqueous solution behavior, Macromol. Chem. Phys., 206, 2038, 2005. 

Wang, T. K., Iliopoulos, I., Audebert, R., Aqueous-Solution Behavior of Hydrophobically Modified Poly(acrylic Acid), in Water-Soluble Polymers Synthesis, Solution Properties and Applications, Shalaby, S.W., McCormick, C. L., Butler, G. B., Eds., ACS Symposium Series No. 467, American Chemical Society, Washington, DC, 1991, pp. 218-231. 

Fortunately for most fonnulators, the optimization of cross-linking is usually addressed by the polymer manufacturer. The concerns of the formulator, instead, must be the effects of other ingredients (e.g., surfactants, salts, oils, etc.) on the cross-linked polymer s aqueous solution behavior. We will see that the effeets can be significant. 

Solution Properties. The aqueous solution behavior of polyampholytes is dictated by coulombic interactions between the basic and acidic residues. Polyampholytes have the ability to exhibit both polyelectrolyte and antipolylelectrolyte behavior in aqueous media. Which type of behavior is exhibited depends on factors such as solution pH, copolymer composition, the relative strengths of the acidic and basic residues, and the presence/absence of low molecular weight electrolyte (239). A feature of polyampholytes—in particular those comprised of weak acidic and basic residues—is the so-called isoelectric point, or lEP. This is simply defined as the solution pH at which the polyampholyte is electrically neutral. Statistical polyampholytes often remain soluble at and around the lEP whereas block polyampholytes tend to be soluble above and below but insoluble at this critical pH. The lEP may be determined either by titration or by measuring the reduced viscosity as a function of pH—the lEP also represents the point at which the polyampholyte chain is in its most compact conformation and thus corresponds to the minimum in reduced viscosity (239,266). With a knowledge of the respective piiLa s and copolymer composition it is also possible to predict the lEP (267). 

Solution Properties. Zwitterionic polymers show interesting aqueous solution behavior. As a general rule, they are insoluble in pure water due to the formation on intra- and interchain ion contacts resulting in an ionically cross-linked network-type structure. Polyampholytes and polybetaines which are not soluble become soluble upon the addition of low molecular weight electrolytes, such as NaCl (Fig. 51). This dissolution process can best be understood in terms of the low molecular weight electrolyte penetrating the ionically cross-linked network whereupon the ions screen the net attractive interactions between the polymer chains and hence promote solubility. The addition of the salt also results in an-tipolylelectrolyte behavior, ie chain expansion upon the addition of the salt. 

Solution interactions are ubiquitous in most pharmaceutical processes in both micro and macroscopic regimes. Water is a major component of the vapor and liquid phases that co-crystals encounter therefore, it is natural to ask what the consequences of such solution phase processes are on co-crystal aqueous solution behavior and what errors can occur if they are ignored. The answers to these questions will be addressed in the following sections. 

MUHer, A.H.E., Cai, Y, Hartenstein, M., Gradzielski, M., Zhang, M., Mori, H. and Pergushov, D.V. (2004) Effect of topology on the aqueous solution behavior of amphiphilic block- and graft copolymers of fj-butylacrylate and acrylic acid. ACS Polym. Prepr. (Div. Polym. Chem.), 45(2), 267-268. 

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