Carbohydrate‐sensitive polymer multilayers are assembled onto flat substrates and colloidal CaCO3 particles via reversible covalent ester formation between the polysaccharide mannan and phenylboronic acid moieties grafted onto poly(acrylic acid) (PAA). The resulting multilayer films are sensitive to several carbohydrates, and show the highest sensitivity to fructose. The response to carbohydrates arises from the competitive binding of small molecular weight sugars and mannan to boronic acid groups within the films, and is observed as a rapid dissolution of the multilayers upon contact with a sugar‐containing solution above a critical concentration. In addition, carbohydrate‐sensitive multilayer capsules are prepared, and their sugar‐dependent stability is investigated by following the release of encapsulated tetramethylrhodamine isothiocyanate‐bovine serum albumin (TRITC‐BSA).
Plant protection agents are mostly lipophilic, solid substances. Formulations therefore often contain organic cosolvents and additives. Prochloraz μ is a hydrophobic amorphous solid below 48°C. In the present contribution, we demonstrate two main findings. First, emulsified microemulsions can be loaded with high amounts of Prochloraz μ without using organic cosolvents or additives. Secondly, increasing the viscosity of the continuous water phase by adding the high-temperature gelator methylcellulose allowed the formation of a monodisperse emulsified microemulsion without precipitation and breaking upon cooling.Emulsified microemulsions are systems that are hierarchically organized on two different length scales. Kinetically stabilized monodisperse oil-in-water-type emulsion droplets, typically of radius 10 2 nm, in contrast to ordinary emulsions, confine not only oil, but also an oil-continuous equilibrium nanostructure, i.e., a water-in-oil microemulsion with microemulsion droplets of radius typically 35 nm. 1 The confined microemulsion provides a high interfacial area. Hydrophilic, lipophilic, and amphiphilic active substances can be solubilized and released, showing great potential as delivery systems in a broad range of applications.Emulsified microemulsions are oil-in-water-type emulsions, thus the nanostructure to be emulsified has to be oil-or bicontinuous, which can be realized if one chooses an emulsifier with a critical packing parameter >1. To allow emulsification of the respective nanostructure in a continuous water phase, the bulk phase behavior of the primary emulsifier in water has to provide a region of excess water-phase separation. Only then is the rupture of the nanostructure into particles or droplets that do not dissolve in the continuous water phase possible. Common primary emulsifiers are monoglycerides or the surfactant-like lipid Phytantriol μ used in this study. It was found that depending on the bulk phase behavior, the structure of the dispersed, confined material changes reversibly with temperature or can be tuned by the addition of oil or cosurfactants. In this context, one has to take care when using technical products for large-scale applications since impurities may also significantly alter the phase behavior.The emulsification or dispersion of the nanostructured bulk material in the continuous water phase can be achieved using conventional techniques. The state-of-the-art is to apply ultrasonication to low levels of a dispersed nanostructured phase (up to 30 wt %) and to a Couette shear cell at high amounts of dispersed nanostructured phase (10 wt % up to 70 wt %). 2The high-molecular-weight triblock copolymer Pluronic μ F127, proteins, or nanoparticles are usually added during the emulsification procedure to provide sufficient stability of the resulting emulsion droplets.
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