Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems

Polymers for enhanced oil recovery: A paradigm for structure–property relationship in aqueous solution

pH-Responsive polymers are systems whose solubility, volume, and chain conformation can be manipulated by changes in pH, co-solvent, and electrolytes. This review summarizes recent developments covering synthesis, physicochemical properties, and applications in various disciplines. A variety of synthetic methodologies comprising of emulsion polymerization and living radical polymerization techniques are described, and some of their salient features are highlighted. Several polymeric systems, such as homopolymers, block copolymers, microgels, hydrogels and polymer brushes at interfaces are reviewed, where important characteristics that govern their behavior in solutions are described. Potential applications of these systems in controlled drug delivery, personal and home care, industrial coatings, biological and membrane science, viscosity modifiers, colloid stabilization, and water remediation, are discussed.

pH-Responsive polymers: synthesis, properties and applications

Water soluble polymers with pendant hydrophobic substituents associate in water to form extended structures. Solutions of the polymers have important applications in technologies ranging from paints and paper coatings (as rheology modifiers) to DNA sequencing (where the network structure serves as a sieving medium). Recent experiments are beginning to reveal the nature of the structures formed and their response to shear. Many facets of the behavior of these polymers are under active investigation.

http://mitran-lab.amath.unc.edu:8082/subversion/Papers/2011/VE_Entrain_JCP_Spec_Issue_MMS/biblio/NetworkModels/WennikYekta_AssociativePolymersAqueousSolution_1997.pdf

Associative polymers in aqueous solution

Principles of Polymer Science and Technology in Cosmetics and Personal Care

Rheology measurements and fluorescent probe experiments were used to study the association process in aqueous solutions of an alkali swellable copolymer of methacrylic acid, ethyl acrylate, and an ethoxylated hydrophobic monomer The pyrene-probe experiments monitor hydrophobic cluster formation in the polymer solution and indicate a rearrangement of the system as a function of pH The polymer, present as a latex at pH < 4, dissolves at pH 57 In this solution, many small hydrophobic domains are present As the pH is raised and the polymer further neutralized, the viscosity of the solution increases, accompanied by formation of a smaller number of larger hydrocarbon domains, detected as a large increase in the extent of pyrene excimer emission

Fluorescence Studies of an Alkaline Swellable Associative Polymer in Aqueous Solution

The effects of salt on four model hydrophobically modified alkali-soluble emulsion (HASE) associative polymers were studied. Their reduced viscosities in aqueous solution at different salt concentrations (10 -4 to 10 -1 M) were measured and the corresponding intrinsic viscosities were determined. The results show that the intrinsic viscosity at any given salt concentration decreases as the hydrophobicity of the hydrophobes (i.e., n in the side chain C n H 2n+4l ) increases. The interpretation is that stronger intra-molecular association of the more hydrophobic macromonomer leads to smaller polymer molecular coils. An increase of salt content in the solution causes the reduced viscosities of all the model polymers to decrease. This is believed to be the result of excess positive ions in solution which have a shielding effect and reduce the mutual repulsion of the charges along the polymer backbone. In dilute solution the hydrophobic associations of the model associative polymers are predominantly intra-molecular. The addition of salt to the polymer solutions hinders the inter-molecular interaction of the model polymers. The increase in salt content also leads to an increase of intra-molecular aggregations of the hydrophobes of the model associative polymers. Stiffness indices such as the stiffness parameter B and the persistence chain length were used to correlate the polymer conformation of the model associative polymers in NaCI solutions.

Liang Guo

Papers

Fluorescence Studies of an Alkaline Swellable Associative Polymer in Aqueous Solution

Effects of salt on the intrinsic viscosity of model alkali-soluble associative polymers