The Use of Polymer and Surfactants for the Microencapsulation and Emulsion Stabilization

Abstract

Polymer/surfactant mixtures have a wide range of industrial and technological applications, one of them being the use in microencapsulation and emulsion stabilization processes. These mixtures are able to form adsorption layers at the surface of oil droplets and so affect the emulsion stability, which depends on the polyelectrolyte/surfactant nature, concentrations ratio, method of the emulsification, etc. Polyelectrolytes alone show low surface activity in contrast to surfactants, which adsorb at the water/oil interface, making the droplets charged, but they are insufficient to stabilize emulsions. When an oppositely-charged polymer is added to the surfactant solution, a steric barrier is formed, which prevents coalescence and enhances the stability. The present review is devoted to the recent studies of the use of polymer/surfactant mixtures for the encapsulation of active ingredients and stabilization of single and double emulsions. Active ingredients are added to the oil phase prior to emulsification so that any subsequent dissolution of the core, like in other encapsulation protocols, can be omitted. By measuring the interfacial tension and dilational rheology it is possible to find optimum conditions for the emulsion formation and hence for encapsulation. Therefore, such systems have become a prominent approach for the encapsulation of active ingredients.

Dynamic Measurements with the Bicone Interfacial Shear Rheometer: Numerical Bench-Marking of Flow Field-Based Data Processing

“…The direct problem merely consists of finding the value of the complex amplitude ratio that corresponds to the programmed values of the frequency, ω, and the complex interfacial viscosity, η * s prog . Hence, it suffices to calculate the corresponding values of the complex Reynolds and Boussinesq numbers, respectively, Re * prog and Bo * prog , and to solve Equation (3) with the boundary conditions specified by Equations (4) and (5). Then, the numerically-obtained complex velocity amplitude function, g * prog (r,z), was used to calculate the value of the complex amplitude ratio, AR * prog (ω, η * s prog ).…”

“…Systems such as tear film, the lung's internal fluid film, cell membranes, foams, and emulsions constitute examples of complex interfacial fluid systems whose dynamical properties play a crucial role regarding their function or utility. Indeed, knowledge of the mechanical properties of such fluid interfacial systems is an essential factor in the development of medical therapies in lung [2] or eye diseases [3], or in the stability and performance of industrial products in the food [4], personal care [5,6], and oil recovery sectors [7].…”

Soft Cationic Nanoparticles for Drug Delivery: Production and Cytotoxicity of Solid Lipid Nanoparticles (SLNs)

“…The behavior of amphoteric surfactants is pH-dependent, being able of depicting a net positive charge (cationic) at low pH, a net negative charge (anionic) at high pH, and null net charge (zwitterionic) at intermediate pH values [13]. Surfactants have been used for a wide range of industrial applications in different sectors, e.g., foods, cosmetics, pharmaceuticals, with emphasis in the production of micro and nanoparticles [14]. The positive surface charge provided by the use of cationic surfactants may improve the cell-particle interaction as SLNs are attracted by the negatively charged membrane phospholipid.…”

“…However, the interaction of cationic SLNs with the cells may be followed by some degree of toxicity. Indeed, it has been documented that non-ionic surfactants are less toxic, than ionic surfactants [3,15], while cationic surfactants have been reported to produce higher toxicity, as a result of their higher interaction with cell membranes [3,14,16]. Among cationic surfactants, CTAB (cetyltrimethylammonium bromide) and DDAB (dimethyldioctadecylammonium bromide) have been used in various industrial processes (e.g., as biocides and antiseptic agents [17]), and in the production of drug-loaded nanoparticles for various applications [4,[18][19][20][21][22][23].…”

Stability of polyethylenimine solution‐in‐liquid paraffin emulsion for preparing polyamine microspheres with potential adsorption for ionic dyes

“…For the preparation of the PEI microsphere, the PEI emulsion was prepared and should be stable enough for maintaining the integrity of emulsion during the reaction processes. PEI contains a high density of amino groups, which can electrostatically interact with ionic stabilizer of emulsion impairing the emulsion stability . Nonionic surfactants do not dissociate in solution to yield a charge.…”