Solution Properties of a Hydrophobically Associating Cellulosic Polymer

Abstract

Electron spin resonance spectroscopy has been used to investigate the solution properties of a hydrophobically associating cellulosic polymer. Nitroxide spin labels covalently attached to the cellulosic backbone have given information with regard to the segmental motion of the polymer chains, whereas nitroxide spin probes have demonstrated the formation of regions of hydrophobicity above a critical polymer concentration. The data is consistent with the formation of an extensive three--dimensional network in which the hydrophilic cellulosic backbones are effectively cross-linked by the intermolecular association of neighbouring hydrophobic side chains. The work has been extended to study the interaction of the polymer with sodium dodecyl sulphate surfactant and the electron spin resonance data has been used to elucidate the mechanism of interaction, and to explain the unusual rheological behaviour.Hydrophobically associating polymers are finding increasing industrial use due to their ability to impart improved rheological behavior to particulate dispersions (1,2). Consequently, there have been a number of research publications concerning such polymers over recent years (3-13). Essentially, these polymers consist of a hydrophilic backbone and possess a small number of hydrophobic side chains, usually in the range of 8 to 40 carbon atoms in length. Whilst the nature of their backbone usually renders the polymer soluble in aqueous media, intermolecular association of the hydrophobic groups leads to the formation of a weak three-dimensional network structure giving rise to solutions of very high viscosity at low shear rates (8). Addition of surfactants to solutions of hydrophobically associating polymers has also been shown to have a dramatic effect on the rheological properties

Salt Tolerance of an Aqueous Solution of a Novel Amphiphilic Polysaccharide Derivative

“…Aqueous solutions of hydrophobically modified polysaccharide derivatives, which can form three-dimensional network structures through the intermolecular associations of their hydrophobic side chains, have been investigated with respect to their viscoelastic properties, aggregation numbers, and surface tensions. − Several previous reports have described the interactions between hydrophobically modified water-soluble polymers and anionic surfactants, and have discussed the unique rheological properties of these mixed polymer−surfactant solutions. − In particular, the effects of salt addition on the polymer−surfactant associations within these mixtures have been the focus of much interest. − However, despite the growing body of literature concerning hydrophobic nonionic polymers, relatively little is known about amphiphilic polymers that contain both hydrophobic and hydrophilic substituents.…”