Highly Viscoelastic Wormlike Micellar Solutions Formed by Cationic Surfactants with Long Unsaturated Tails

Abstract

Cationic surfactants having long (C22) mono-unsaturated tails were studied in aqueous solutions containing salt using steady and dynamic rheology. The surfactant erucyl bis(hydroxyethyl)methylammonium chloride self-assembles into giant wormlike micelles, giving rise to unusually strong viscoelasticity. Under ambient conditions, the viscosity enhancement due to surfactant exceeds a factor of 107. Some samples behave as gel-like solids at low temperatures and revert to the viscoelastic (Maxwellian) response only at higher temperatures. These samples display appreciable viscosities (>10 Pa·s) up to very high temperatures (ca. 90 °C). Salts with counterions that penetrate into the hydrophobic interior of the micelles, such as sodium salicylate, are much more efficient at promoting self-assembly than salts with nonbinding counterions, such as sodium chloride. Changing the surfactant headgroup to the more conventional trimethylammonium group reduces the viscosity at high temperatures.

A systematic rheological study of alkyl amine surfactants for fluid mobility control in hydrocarbon reservoirs

“…In particular, as temperature increases, the viscosity initially rises to an inflection point then begins degrading afterward and this process can repeat at higher temperatures (Rabie and Nasr-El-Din 2015). This viscosity ''enhancement'' suggests that not all of the micelles entangled to form wormlike micelles at low temperatures (Raghavan and Kaler 2001). As temperature increases, the wormlike micelles grow to a lesser extent thereby reducing the micellar length and leading to a decrease in rheological properties .…”

“…The length and composition of the tail are of primary importance when it comes to altering rheological properties of the solution (Raghavan and Kaler 2001). In this case, surfactants with coco-based tails, such as ARM and ECA, typically contain 12-16 carbon atoms, while surfactants with tallow-based tails, such as DTTM and EDM, consist of 14-18 carbons.…”

“…The presence of hydrophobic terminals, such as methyl groups found in DTTM and ARM, can dehydrate the surfactant molecules with excess salt in the aqueous solution. This hydrophobicity favors the growth of long micelles, since hydrophobic molecules have higher end-cap energies, and end-cap energy is exponentially proportional to the micellar length (Berret 2006;Raghavan and Kaler 2001;Raghavan et al 2002). End-cap energy represents the excess packing energy for surfactants with preferential cylindrical aggregation and is defined as the energy required to create two new chain ends for neutral micelles (Berret 2006).…”

Effects of Temperature on the Rheological Behavior of Worm-like Micelles in a Mixed Nonionic Surfactant System

“…Wormlike micelles are known to mutually entangle to form a gel with a high viscoelasticity, which arises due to the formation of a transient network structure. It is already known that worm-like micelles can be formed by the addition of aromatic salts such as sodium salicylate to cationic surfactants such as cetyltrimethylammonium bromide or cetylpyridinium chloride [1][2][3][4] . Recently, Kunieda et al [5][6][7][8] reported that a worm-like micelle of high viscoelasticity was formed by mixing two types of nonionic surfactants with very different HLB (hydrophilic-lipophilic balance) values.…”

“…Raghavan et al 4) examined the influence of temperature on the rheological properties of worm-like micelles, and they clarified that worm-like micelles formed from ionic surfactants typically show an exponential decrease in zeroshear viscosity (h 0 ) upon heating. However, there were few reports about the temperature behavior of worm-like micelles consisting of nonionic surfactants 10,11) .…”