The Influence of the Surface Chemistry of Cellulose Nanocrystals on Ethyl Lauroyl Arginate Foam Stability

Abstract

Guanidine-based surfactant ethyl lauroyl arginate (LAE) and cellulose nanocrystals (CNCs) form complexes of enhanced surface activity when compared to pure surfactants. The LAE-CNC mixtures show enhanced foaming properties. The dynamic thin-film balance technique (DTFB) was used to study the morphology, drainage and rupture of LAE-CNC thin liquid films under constant driving pressure. A total of three concentrations of surfactant and the corresponding mixtures of LAE with sulfated (sCNC) and carboxylated (cCNC) cellulose nanocrystals were studied. The sCNC and cCNC suspension with LAE formed thin films, with stability increasing with surfactant concentration and with complex rheological properties. In the presence of LAE, the aggregation of CNC was observed. While the sCNC aggregates were preferentially present in the film volume with a small fraction at the surface, the cCNC aggregates, due to their higher hydrophobicity, were preferentially located at film interfaces, forming compact layers. The presence of both types of aggregates decreased the stability of the thin liquid film compared to the one for the LAE solution with the same concentration. The addition of CNC to LAE was critical for foam formation, and foam stability was in qualitative agreement with the thin films’ lifetimes. The foam volume increased with the LAE concentration. However, there was an optimum surfactant concentration to achieve stable foam. In particular, the very resistant foam was obtained with cCNC suspensions that formed the interfaces with a complex structure and rheology. On the other hand, at high LAE concentrations, the aggregates of CNC may exhibit antifoaming properties

Particle Size and Rheology of Silica Particle Networks at the Air–Water Interface

“…Understanding the parameters governing the assembly of particles at interfaces is vital towards tailoring the physico-chemical characteristics of networks in order to control the stability of multiphase fluidic systems, such as emulsions and foams [14,[19][20][21][22].…”

“…Understanding the parameters governing the assembly of particles at interfaces is vital towards tailoring the physico-chemical characteristics of networks in order to control the stability of multiphase fluidic systems, such as emulsions and foams [ 14 , 19 , 20 , 21 , 22 ]. Furthermore, in various applications involving multiphase fluids, such as enhanced oil recovery and bio-film degradation [ 23 , 24 , 25 , 26 , 27 , 28 ], the interface is present in non-equilibrium conditions and is subjected to flows causing shear and compressional stresses [ 29 ].…”