Dynamic Light Scattering of Semi‐Dilute Hydrophobically Modified Alkali‐Soluble Emulsion Solutions with Varying Length of Hydrophobic Alkyl Chains

Abstract

Dynamic light scattering as well as rheological technique was used to study the semi‐dilute hydrophobically modified alkali‐soluble emulsion (HASE) solutions. The solution viscosity increases dramatically, when the overlap concentration C* is exceeded. Two diffusional modes are evident from the decay time distributions of light scattering and they are related to the hydrodynamic correlation length and the apparent hydrodynamic radius of the HASE clusters. The hydrodynamic correlation lengths, as determined from the fast diffusion mode decrease in proportion to the polymer concentrations but increase with increasing the hydrophobicity of the hydrophobes of the macromonomers. The apparent hydrodynamic radii of the clusters, as determined from the slow diffusion mode, increase with increasing polymer concentrations. When the carbon number of the hydrophobes is increased from C1 to C8, both the viscosities and diffusion coefficients of the slow mode remain almost unchanged. However, they are strongly dependent on the carbon chain length when the carbon number exceeds C12, especially for the polymer with C20 alkyl chains. The solution viscosities decrease and diffusion coefficients of the slow mode increase with increasing temperatures, however, the parameters of Dη/T remain constant.

Evaluation of alternative comonomers for the production of ASE and HASE thickeners

“…This is due to the stronger association generated by longer hydrophobic tails. Similar results have been observed by other authors using different AM, with varying lengths [7,8,27]. This difference in viscosity is also observed at lower concentrations, as shown in Fig.…”

“…7b it is shown that there is a significant decrease in turbidity levels for smaller latex particles. This effect could be related to the fact that the reduction in particle diameter enhances the changes of intermolecular hydrophobic associations relative to intramolecular associations, decreasing the size of these hydrophobic domains and therefore scatters less visible light [26,27]. From Fig.…”

Rheological properties of hydrophobically modified polyelectrolyte systems: Concentration effects

“…The slower chain reptation will lead to the formation of longer multiple relaxation times observed in the polymer system as shown in the relaxation spectra. This behavior is proposed in Figure 8 34,35 for concentration greater than the established network concentration C**.…”

“…The reduction in the aggregation number in this low concentration regime reduces the lifetime of the polymer system as indicated by the shifting of fast relaxation peak to lower time as depicted in Figure 7(a and b). Such behavior was also detected by dynamic light scattering technique performed on HASE systems, 34,35 where the correlation length between the hydrophobic junctions decreases with increasing polymer concentration. This behavior was pictorially presented in Figure 8, where the concentration is increased from cluster overlapping concentration, C*, to established network concentration, C**.…”

Relaxation behavior of hydrophobically modified polyelectrolyte solution under various deformations

“…Hydrophobically modified alkali-soluble (HASE) associative polymer has receive increasing attentions in recent years [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Most of these studies focused on describing the microstructure and the behavior of HASE in the presence of surfactants.…”