Topological Dynamics of Micelles Formed by Geometrically Varied Surfactants

Abstract

The molecular architecture of sugar-based surfactants strongly affects their self-assembled structure, i.e., the type of micelles they form, which in turn controls both the dynamics and rheological properties of the system. Here, we report the segmental and mesoscopic structure and dynamics of a series of C16 maltosides with differences in the anomeric configuration and degree of tail unsaturation. Neutron spin-echo measurements showed that the segmental dynamics can be modeled as a one-dimensional array of segments where the dynamics increase with inefficient monomer packing. The network dynamics as characterized by dynamic light scattering show different relaxation modes that can be associated with the micelle structure. Hindered dynamics are observed for arrested networks of worm-like micelles, connected to their shear-thinning rheology, while nonentangled diffusing rods relate to Newtonian rheological behavior. While the design of novel surfactants with controlled properties poses a challenge for synthetic chemistry, we demonstrate how simple variations in the monomer structure can significantly influence the behavior of surfactants.

Fabrication and Enzymatic Disorganization of Multiresponse Worm-Like Micelles

“…Beyond this point, no significant changes in η 0 were observed (Figure 6A). Simultaneously, it should be noted that shearthinning 40,42 ceased when the pH dropped below 2.3 (Figure S11B). The cryo-TEM result further confirmed that the PCB-AzoNa WLMs had been destroyed completely at pH 2.0 (Figure 6B).…”

“…Besides, a typical shear-thinning phenomenon was observed in the plot of shear rate (s −1 ) versus steady-state viscosity (η, mPa•s) for the PCB-AzoNa system (Figure S4), giving another strong signal of the formation of WLMs. 40,42 The zero-shear viscosities (η 0 , mPa•s) were obtained by extrapolating the viscosity plot (Figure S4) along the plateau to zero-shear rate. Then, the appropriate molar ratio of AzoNa to PCB (n AzoNa /n PCB ) was determined from the dependence of η 0 on n AzoNa /n PCB (Figure 1B).…”

“…However, slight modifications in the molecular structure of surfactants may lead to significant changes in their self-assembly behavior and aggregate structure. 40 Thus, the second reason why we are particularly interested in PCB is that, whether PCB can also form WLMs in the PCB-AzoNa solution, in the same way as conventional cetyltrimethylammonium bromide (CTAB) 13 does, due to the presence of the ester bond near the hydrophilic headgroup (Scheme 1A). If (i) PCB-AzoNa WLMs can be successfully constructed and (ii) PCB-AzoNa WLMs can also show obvious stimulus-response to light, heat, and pH as well as the BChE-catalytic hydrolysis of PCB, not only can the construction of a multiresponse WLMs be achieved but also the BChE-catalytic hydrolysis of PCB offers the possibility to safely dispose 39 waste WLMs.…”

“…The primary degradation products of PCB are the common metabolites, choline and fatty acid (Scheme D). However, slight modifications in the molecular structure of surfactants may lead to significant changes in their self-assembly behavior and aggregate structure . Thus, the second reason why we are particularly interested in PCB is that, whether PCB can also form WLMs in the PCB-AzoNa solution, in the same way as conventional cetyltrimethylammonium bromide (CTAB) does, due to the presence of the ester bond near the hydrophilic headgroup (Scheme A).…”

Performance Evaluation and Formation Mechanism of Viscoelastic Surfactant Fracturing Fluids with Moderate Interfacial Activity Enhanced by Janus-SiO2 Nanoparticles

“…Hydraulic fracturing technology has greatly stimulated the productivity of oil-gas wells in low-permeability formations for several decades. − In recent years, polymer-based fracturing fluids have dominated the fracturing industry due to their excellent fracturing performance. A major issue with these fluids is the formation damage, inhibiting their ability to improve production efficiency. , The eco-friendly viscoelastic surfactant (VES) fracturing fluid, which comprises highly entangled wormlike micelles (WLMs), is an ideal candidate to replace the traditional fracturing fluid.…”