Plant Latex as a Versatile and Sustainable Emulsifier

Abstract

Emulsions are a class of high-surface-energy materials typically stabilized by surfactants, polymers, particles, or a combination of these. There has been considerable effort to develop new emulsifiers by exploiting developments in synthetic chemistry; however, synthetic surface-active species may assist in the stabilization of a specific type of immiscible liquid–liquid systems. That is, one stabilizer does not provide a solution for all interface stabilization problems. Moreover, the synthesis of surface-active systems involves high production costs and complex synthesis routes and generates a substantial amount of chemical waste. In this work, we show that plant latex, an aqueous dispersion of colloidal-scale particles in which small as well as large bioactive species are also present, can be used as a versatile and sustainable source for interface stabilization. The constituents of the latex are found to reduce the oil–water interfacial tension due to the spontaneous adsorption of surface-active species present in the latex. The surface-active nature of latex is further exploited to obtain very stable single emulsions, double emulsions (DEs), and multiple emulsions (MEs). Our results conclusively show that plan latex is a potential versatile source for the stabilization of emulsions created by considering different types of immiscible liquid systems.

Tailoring Pickering Double Emulsions by in Situ Particle Surface Modification

“…In general, a hydrophilic particle (θ < 90°) gives an o/w emulsion, whereas a hydrophobic particle (θ > 90°) produces w/o emulsions. When a mixture of hydrophilic and hydrophobic particles is used, double or multiple emulsions form. , However, the type of double emulsion (w/o/w or o/w/o) can be controlled by choosing the appropriate proportion of hydrophilic and hydrophobic particles in the system. ,, Thus, the use of a mixture of hydrophilic and hydrophobic particles is vital for the design of double emulsions. In the present work, the sequential addition method is employed to effect the formation of double emulsions in single- and two-particle systems.…”

“…12,13 However, the type of double emulsion (w/o/w or o/w/o) can be controlled by choosing the appropriate proportion of hydrophilic and hydrophobic particles in the system. 18,20,28 Thus, the use of a mixture of hydrophilic and hydrophobic particles is vital for the design of double emulsions. In the present work, the sequential addition method is employed to effect the formation of double emulsions in single-and two- particle systems.…”

“…Most of the earlier studies were performed using premodified particles of different surface chemistry, but in situ surface modification of particles has not yet been explored in the context of double emulsion formulation. Recently, some efforts have been made to prepare double emulsions in a single step by using biodegradable materials such as corn-peptide functionalized calcium phosphate (CP-CaP) particles and plant latex particles . However, there are no reports that have explored the stabilization of different types of double emulsions via a single-step method using a multicomponent system by tuning the wettability of one type of particle in the presence of another oppositely charged particle.…”

Oil-in-Water Emulsions Stabilized by Hydrophilic Homopolymers

“…This figure indicates the presence of birefringence in all PEO-stabilized emulsions, indicating the presence of the PEO polymer layer at the decane–water interface. A similar birefringence has been observed in the emulsions stabilized by plant latex . It has been reported that the PEO solution under magnetic stirring could degrade PEO chains into shorter chains and facilitate the formation of insoluble aggregates of several microns.…”

“…Oil-in-water emulsions find wide applications in cosmetic, paint, pharmaceutics, petroleum, and food industries . Surfactants, particles, and polymers have been studied as emulsifying agents. − However, attention in recent times has been given to naturally occurring emulsifiers such as biosurfactants, phospholipids, biopolymers, and colloidal particles. , Water-soluble polymeric emulsifiers have the balance of hydrophilic and hydrophobic components in their structure to adsorb at the oil–water interface, and their eco-friendly character is an added advantage over the synthetic surfactants. , The polymer at interfaces is widely studied with regard to several aspects such as adsorption, interfacial effects, colloidal stability, and interfacial rheology . For instance, cellulose, which is an abundantly available natural polymer, has been used to stabilize oil-in-water emulsions. , Scanning electron microscopy images of the oil drops showed the presence of a cellulose film at the drop surface.…”