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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.

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A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations—0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture

The synthesis and properties of submicrocontainers with a shell of nanoparticles of silicon dioxide and a core of polymerized 3-(Trimethoxysilyl) propyl methacrylate loaded with 5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) are considered. The resulting containers were characterized by scanning electron microscopy SEM, laser correlation spectroscopy and thermogravimetric analysis. The obtained submicrocontainers show low polydispersity with a small increase in size in comparison with the initial droplet size of the Pickering emulsion. The Zeta potential of the final containers was sufficiently negative at pH7 to be stable. The maximum release of encapsulated biocide was observed over approximately 24–27 h with a lease of about 78% of the encapsulated biocide during 3.5 h. The effectiveness of the encapsulated biocide by the Pickering emulsion technique was studied by tests on the growth rate of a microfungi colony (Aspergillus niger, Aspergillus awamori) and the growth rate of the bacteria Bacillus cereus. The test shows that the submicrocontainers of DCOIT facilitate a growth inhibition of 70% against 52% for the free biocide after 5 days; this is due to the fact that free biocide loses its activity promptly, while the encapsulated biocide is released gradually, and thus retains its effectivity for a longer time.