Molecular Brush Surfactants: Versatile Emulsifiers for Stabilizing and Structuring Liquids

Abstract

Using amphiphilic molecular brushes to stabilize emulsions usually requires the synthesis of specific side chains, which can be a time-consuming and difficult challenge to meet. By taking advantage of the electrostatic interactions between water-soluble molecular brushes and oil-soluble oligomeric ligands, the in situ formation, assembly and jamming of molecular brush surfactants (MBSs) at the oil-water interface is described. With MBSs, stable emulsions including o/w, w/o and o/w/o can be easily prepared by varying the molar ratios of the molecular brushes to the ligands. Moreover, when jammed, the binding energy of MBSs at the interface is sufficiently strong to allow the stabilization of liquids in nonequilibrium shapes, i.e., structuring liquids, producing an elastic film at the interface with exceptional mechanical properties. These structured liquids have numerous potential applications, including chemical biphasic reactions, liquid electronics, and all-liquid biomimetic system.

The Assembly and Jamming of Nanoparticle Surfactants at Liquid–Liquid Interfaces

“…Since a single SPAA NP consists of one β‐CD, only one Ad‐PLLA chain is attached to SPAA NP. It should be noted that the interfacial activity of PAA chain can be enhanced by decreasing the pH, in terms of the increased degree of protonation of the carboxylic acid groups (p K a =4.2) and, therefore, the hydrophobicity [21] . To avoid the less‐controlled wetting conditions and spontaneous assembly of SPAA NPs at the interface, which can potentially influence the resultant binding energy of the NPS, the pH of the aqueous phase is fixed at 9.0 in the following experiments unless specifically noted, in which the carboxylic acid groups are almost fully deprotonated (Figure S7).…”

“…The binding energy of the NP to the interface is sufficiently increased to hold the NPSs at the interface under compression, causing the NPSs to jam, affording the possibility to arrest liquids in highly non‐equilibrium shapes, i.e., structuring liquids, which shows a myriad of potential applications in encapsulation, biphasic reactors, and programmable liquid constructs [15–20] . In addition to NPs, small molecules and polymers can also be used as building blocks to generate interfacial assemblies, underscoring the generality of NPSs [21–28] . A fundamental question arises as to the dynamic nature of the NPSs at the interface and whether the size‐dependent assembly of NPSs to the interface can be induced, since part of the NP surface is anchored by polymeric ligands in a NPS system, and the NPSs are irreversibly bound to the interface.…”

Strategies for dispersion of cariogenic biofilms: applications and mechanisms

“…The electrostatic interactions involved in the bonding of the biofilm matrix could be affected by hydrophilic agents ( Venault et al, 2014 ), surfactants ( Wang et al, 2021 ), and metal chelators ( Roman et al, 2014 ). Such electrostatic interaction agents have been found to destabilize the biofilm matrix and facilitate biofilm separation ( Xavier et al, 2005 ).…”

The Assembly and Jamming of Nanoparticle Surfactants at Liquid–Liquid Interfaces

“…[15][16][17][18][19][20] In addition to NPs, small molecules and polymers can also be used as building blocks to generate interfacial assemblies, underscoring the generality of NPSs. [21][22][23][24][25][26][27][28] A fundamental question arises as to the dynamic nature of the NPSs at the interface and whether the size-dependent assembly of NPSs to the interface can be induced, since part of the NP surface is anchored by polymeric ligands in a NPS system, and the NPSs are irreversibly bound to the interface. In previous studies, by using electrostatic interactions to generate NPSs at the interface, a displacement behavior of NPs with different sizes was observed.…”