Solution properties sulfonate monomers

This chapter describes the synthesis, kinetics, and solution properties for copolymers ofN-vinylpyrrolidone (NVP) with sulfonate ionic and zwitterionic monomers. Examples of the sulfonate ionic monomers are sodium styrenesulfonate (NaSS) and sodium acrylamido-2-meth-ylpropanesulfonate (NaAMPS) an example of the zwitterionic sulfonate monomer is 2-hydroxyethyt)dimethyl(3-sulfopropyt)-ammonium inner salt, methacrylate (SPE). The NVP-NaAMPS monomer pair was exceptional, showing evidence for donor-acceptor character and an alternating tendency in copolymerization. The NVP copolymers containing simple sulfonate ionic monomers e.g., NaAMPS) showed polyelectrolyte solution properties. On the other hand, the NVP copolymers with zwitterionic sulfonate monomers showed antipoly electrolyte solution behavior. 

Poly(N-vinylpyrrolidone), P(NVP), is a nonionic, water-soluble polymer with high thermal and hydrolytic stability (7-9). Copolymers of N-vinylpyr-rolidone (NVP) with various carboxylate and carboxylate-precursor monomers (e.g., acrylic acid, sodium acrylate, crotonic acid, itaconic acid, and maleic anhydride) are also well-known (10). In addition, the homo- and copolymerization kinetics of these monomers are well-established. On the other hand, reports of copolymerizations of NVP with sulfonate monomers are sparse 11, 12). This chapter describes the synthesis, kinetics, and reactivity ratios for the copolymerization of NVP and some of the newer sulfonate monomers. A comparison of some of the solution properties for such copolymers is also included. 

It has also been shown [254] that a commercial petroleum sulfonate surfactant which consists of a diverse admixture of monomers does not exhibit behavior typically associated with micelle formation (i.e., a sharp inflection of solvent properties as the concentration of surfactant reaches CMC). These surfactants exhibit gradual change in solvent behavior with added surfactant. This gradual solubility enhancement indicates that micelle formation is a gradual process instead of a single event (i. e., CMC does not exist as a unique point, rather it is a continuous function of molecular properties). This type of surfactant can represent humic material in water, and may indicate that DHS form molecular aggregates in solution, which comprise an important third phase in the aqueous environment. This phase can affect an increase in the apparent solubility of very hydrophobic chemicals. 

Information on microviscosity is obtained by studying the excimer forming capabilities of suitable fluorescent probes. The excimer, which is a complex of a ground state and excited state monomer, has a characteristic emission frequency. The intramolecular excimer formation for example, of 1,3-dinaphthyl propane (DNP), is a sensitive function of the microviscosity of its neighborhood. This property, expressed as the ratio of the excimer and monomer yield (/e//m) for DNP, has been determined for dodecyl sulfonate solutions and its adsorbed layer for the various regions of the adsorption isotherm (Fig. 4.18) (Somasundaran et al., 1986). Comparing the ratios thus obtained to the /e//m values of DNP in mixtures of ethanol and glycerol of known viscosities, a microviscosity value of 90 to 120 cPs is obtained for the adsorbed layer in contrast to a value of 8 cPs for micelles. The constancy of microviscosity as reported by DNP is indicative of the existence of a condensed surfactant assembly (solloids) that holds the probe. 

Polymer 44 undergoes oxidation when treated with perbenzoic acid to generate the highly fluorescent bis(sulfone) 45 (Scheme 21.5) [88]. In this case, the advantageous properties of the polymer over the monomer are its enhanced emission (the fluorescence quantum yield of polymer 45 is six times greater than that of the monomer), fatigue resistance and photostationary state. The improved photochromism and fluorescence are not unique to the polymer in solution and are retained in a film of 45. The significance... 

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