CO₂-Triggered Pickering Emulsion Based on Silica Nanoparticles and Tertiary Amine with Long Hydrophobic Tails

Abstract

We describe a strategy of fabricating CO-triggered oil-in-water Pickering emulsion based on silica nanoparticles functionalized in situ by a trace amount of conventional CO-switchable surfactant, N-(3-(dimethylamino)propyl)alkyl amide (CPMA). By alternately bubbling CO and N at a moderate conditions (30 °C, 80 mL min), silica nanoparticles reversibly switch between amphipathic and hydrophilic as a result of the adsorption of ammonium (CO) and the desorption of tertiary amine (N). The emulsion can then be smart switched "on (stable)" and "off (unstable)", along with homogenization, without needing cooling and heating. The switching of the current tertiary-based system is simple, moderate, and environmentally friendly, without contamination and the restriction of rigorous conditions. The surfactant concentration window of the Pickering emulsion is closely related to the length of hydrophobic tail, and the upper limit is no more than 0.20 cmc of that of the corresponding ammonium surfactant. Such a strategy is also suitable for commercial alkyl tertiary amines, without needing complicated organic synthesis.

Application of pH‐Responsive Viscoelastic Surfactant as Recyclable Fluid at High Temperature

“…Thus, hydrotropes were also an effective way to enhance the viscoelasticity of VES fluids that formed by smart wormlike micelles. Numerous studies have been dedicated to investigate the relationship of structure–property in wormlike micellar solutions (Dai et al, ; Menger and Littau, ; Zhang et al, ). However, the reports on the high temperature (above 80 °C) influence of wormlike micellar solutions were less considered in the research (Baruah et al, n.d., , , ).…”

Effect of Pickering emulsion on the mechanical performances and fracture toughness of epoxy composites

“…Pickering emulsion, which is stabilized by ultrafine particles (for example colloidal silica) of sizes from a few nanometers to hundreds of micrometers, has attracted widespread interest in areas such as pharmaceutics, high‐performance polymer nanocomposites, environment protection, phase change materials, and functional materials . Some of the used stabilized particles are nanocelluloses, TiO 2, cellulose nanocrystals, and silica nanoparticles . It is well known that the nanoparticle stabilizers are adsorbed onto the interface between the two phases and the solutes are well dispersed and homogenized in solvents.…”

“…Leclercq et al produced a water‐in‐oil Pickering emulsion by using a series of polyoxometalate nanoparticles as stabilizers. Zhang et al described a strategy of fabricating CO 2 ‐triggered oil‐in‐water Pickering emulsion based on silica nanoparticles functionalized in situ by a trace amount of conventional CO 2 ‐switchable surfactant.…”

“…34,35 Some of the used stabilized particles are nanocelluloses, 29,36 TiO 2,35 cellulose nanocrystals, 30,37 and silica nanoparticles. [38][39][40][41] It is well known that the nanoparticle stabilizers are adsorbed onto the interface between the two phases and the solutes are well dispersed and homogenized in solvents. Therefore, it is easy to obtain a homogeneous solution which is consisted of nanoparticles Polystyrene/nano-SiO 2 composite microspheres with core/shell structure were synthesized in a Pickering emulsion route using nano-SiO 2 particles as stabilizers.…”

Strategy for Synthesizing Novel Acetamidines as CO2-Triggered Switchable Surfactants via Acetimidates

“…With respect to tertiary amines, their basicity is so weak that stable emulsions can hardly be formed [20]. As such, compounds containing an amidine head [21,22] are attracting more attention due to their mild basicity and superior stability.…”