Monitoring pH-dependent conformational changes in aqueous solutions of poly(methacrylic acid)-b-polydimethylsiloxane copolymer based on fluorescence spectra of pyrene and 1,3-bis(1-pyrenyl)propane

Chemical Engineering Communications

Chen

Jiang

2014

A water-soluble terpolymer, PAAB, was copolymerized using acrylamide (AM), sodium 2-acrylamido-2-methylpropanesulphonate (NaAMPS), and a novel macro-monomer, p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VBE, polymerization degree: 24). This polymer exhibited associating effect and good thickening properties in unsalted and brine solutions, and the effect of salt on apparent viscosity was much weaker than that of the linear associating polymers only containing small hydrophobic monomers. Its brine solution exhibited salt-thickening behavior twice and good resistances to heat because of the incorporation of the functional poly(ethylene oxide) side chains. The PAAB aqueous and brine solutions also displayed obvious shear thickening behavior upon repetitious three-shear cycles. It was found by a scanning electron microscope (SEM) that the polymer chains were extended and large associated structures were formed in brine solutions as well as in water at the PAAB concentrations of 0.05-0.15 g=dL.

Section: Resultsmentioning

confidence: 99%

Viscosity Behavior and Associated Morphologies of a Branched Acrylamide-Based Terpolymer in Water and Brine Solutions

Chemical Engineering Communications

Chen

Jiang

2014

“…Hence, the I e /I m ratio has often been used as an indicator of the degree of interaction between fluorophores. [21,22] For hydrophobically associating polymers, the I e /I m ratio provides a measure to characterize the association degree of hydrophobic segments in the polymer chains and the microviscosity of hydrophobic microdomains. Figure 15 shows the I e /I m values as a function of polymer concentration in water and in the 5 g L −1 NaCl solutions.…”

Section: Influence Of Polymer Concentration On Aggregation In Unsaltementioning

confidence: 99%

Surface and Interface Properties and Associated Behavior in Water and Brine Solutions of an Acrylamide-Based Terpolymer with a Macromonomer

Journal of Macromolecular Science, Part B

Jiang

2012

A novel macromonomer, p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VBE, polymerization degree: 24), was copolymerized with acrylamide (AM) and sodium 2-acrylamido-2-methylpropane-sulfonate (NaAMPS) to form a water-soluble terpolymer (abbreviation: PAAB). It exhibited remarkable surface and interface activities as well as a thickening effect in unsalted and brine solutions. The variation of surface and interface tensions with NaCl concentration was investigated; the interface tensions in water and in a 70 g L −1 NaCl solution were, respectively, 4.1 mN m −1 and 2.3 mN m −1 at a polymer concentration of 0.1 g dL −1 . The intermolecular hydrophobic associations in unsalted and brine PAAB solutions as a function of polymer concentration and the conformation of polymer chains were characterized by a fluorescent probe. The results indicated that the incorporation of long side chains could expand the polymer chains in brine solutions as well as in the unsalted solutions. The probe investigation in the unsalted and brine polymer solutions also showed that the extended monomolecules were dominant at the polymer concentrations lower than 0.05 g dL −1 and that the intermolecular hydrophobic associations were enhanced sharply above the critical association concentrations of 0.10 g dL −1 .

“…Their emission peaks (with intensity I e ) are broad featureless spectral peaks centered at 445-475 nm. Hence, the I e /I m ratio has often been used as an indicator of the degree of interaction between fluorophores (26)(27)(28). For hydrophobically associating polymers, the I e /I m ratio provides a measure to characterize the association degree of hydrophobic segments in the polymer chains and the microviscosity of hydrophobic microdomains.…”

Section: Effect Of Polymer Concentration On Associations In Aqueous Smentioning

confidence: 99%

Thickening and Associating Behavior in Aqueous Solutions of a Terpolymer with Poly(ethylene oxide) Side Chains

Journal of Macromolecular Science, Part A

Cai

Rao

2012

A water-soluble terpolymer (PAVA) was synthesized by aqueous free radical copolymerization technique using acrylamide(AM), sodium 2-acrylamido-2-methylpropane-sulphonate (NaAMPS) and a macromonomer: p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VPEO, degree of polymerization: 10). The remarkable intermolecular hydrophobic associations were formed in water and a brine solution for this polymer, which resulted in a good thickening effect, resistance to salt and salt-thickening. The hydrophobically associating microstructures of PAVA in aqueous solutions were measured by the fluorescent probe and scanning electron microscope. As polymer concentration was increased in water and brine solutions, the associating strength and non-polarity of hydrophobic microdomains increased remarkably. However, at the polymer concentrations higher than 0.20 g/dL, the non-polarity of hydrophobic microdomains tended to remain constant, and the I 1 /I 3 value changed slightly in 0.5 g/dL NaCl. The continuous associating structures were formed by the expanded polymer chains in brine solutions, as well as in water. As the NaCl concentration increased, the non-polarity of associating microstructures increased slowly, but the compact degree of these microstructures increased.