Stimuli-Responsive Bubbles and Foams Stabilized with Solid Particles

Abstract

Particle-stabilized bubbles and foams have been observed and used in a wide range of industrial sectors and have been exploited as a technology platform for the production of advanced functional materials. The stability, structure, shape, and movement of these bubbles and foams can be controlled by external stimuli such as the pH, temperature, magnetic fields, ultrasonication, mechanical stress, surfactants, and organic solvents. Stimuli-responsive modes can be categorized into three classes: (i) bubbles/foams whose stability can be controlled by the adsorption/desorption/dissolution of solid particles to/from/at gas-liquid interfaces, (ii) bubbles/foams that can move, and (iii) bubbles/foams that can change their shapes and structures. The stimuli-responsive characteristics of bubbles and foams offer potential applications in the areas of controlled encapsulation, delivery, and release.

pH-Responsive Aqueous Bubbles Stabilized With Polymer Particles Carrying Poly(4-vinylpyridine) Colloidal Stabilizer

“…Bubble stability depends on the hydrophilicity-hydrophobicity balance of the particle surfaces, in other words, the wettability of the particles at the air-water interface (Ramsden, 1903; Binks and Horozov, 2006; Studart et al, 2006; Fujii and Murakami, 2008; Hunter et al, 2008; Kruglyakov et al, 2011; Stevenson, 2012; Pugh, 2016; Fujii and Nakamura, 2017); therefore, the behavior of bubbles stabilized with these P4VP-PS particles is expected to change at pH values close to the p K a of the P4VP stabilizer in a significant manner. To evaluate bubble forming ability and bubble stability, the bubble formation was estimated after shaking aqueous dispersions of the P4VP-PS aqueous latex particles (5.0 wt%) at different pHs.…”

“…For a long time, it has been known that gas bubbles can be stabilized solely by solid colloidal particles in aqueous media (Ramsden, 1903; Binks and Horozov, 2006; Studart et al, 2006; Fujii and Murakami, 2008; Hunter et al, 2008; Kruglyakov et al, 2011; Stevenson, 2012; Pugh, 2016; Fujii and Nakamura, 2017). The hydrophilicity-hydrophobicity balance of the particle surfaces determines the adsorption behavior of such particles at the air-water interface, and the bubbles stabilized by solid particles of the suitable hydrophilicity-hydrophobicity balance show excellent long-term stability.…”

“…Disruption of bubbles is also often required in practical applications. It has been shown that the stability of bubbles stabilized with stimulus-responsive solid particles can be controlled in situ by application of external stimulus such as pH, temperature, light and magnetic fields, as reviewed recently (Fujii and Nakamura, 2017). In such cases, disruption of bubbles can be realized by decreasing the adsorption energy of the solid particles at the interface or by application of external energy exceeding the adsorption energy.…”

Interfacial Nanoprecipitation toward Stable and Responsive Microbubbles and Their Use as a Resuscitative Fluid

“…[4] However,l ipid systems often lack the stability needed for many practical uses and tremendous efforts have been made to identify alternative shell materials, [5] forexample,proteins [6] and polyvinyl alcohol. [8,9] Furthermore,s timuli-responsive and multifunctional Pickering MBs have also been created for advanced biomedical applications. [8,9] Furthermore,s timuli-responsive and multifunctional Pickering MBs have also been created for advanced biomedical applications.…”

“…[7] Notably,m icro-and nanoparticle-stabilized (Pickering-type) MBs have been developed that exhibit superior stability. [9,10] However,s everal limitations must be overcome before Pickering MBs can be used in vivo.F or example,m any systems contain nondegradable materials,for example,silica, polystyrene,ortoxic additives. [9,10] However,s everal limitations must be overcome before Pickering MBs can be used in vivo.F or example,m any systems contain nondegradable materials,for example,silica, polystyrene,ortoxic additives.…”