Silicone Nanocapsules Templated Inside the Membranes of Catanionic Vesicles

Abstract

A simple and effective way to synthesize hollow silicone resin particles of controlled diameter is presented. The synthesis utilizes catanionic vesicles as templates for the polycondensation/polymerization processes of 1,3,5,7tetramethylcyclotetrasiloxane (D 4 H ) within their membranes. Two different surfactant systems were used to form the vesicular templates: mixtures of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylbenzenesulfonate (SDBS) in the cationic (the DTAB/SDBS system) or anionic (the SDBS/DTAB system) rich region of the phase diagram. The templates obtained from these surfactant mixtures form spontaneously unilamellar vesicles in aqueous solution. The vesicular templates swell upon addition of D 4 H , thus increasing their size. The silicone resin was obtained in acid-or base-catalyzed polycondensation and ring-opening polymerization processes of D 4 H . In the case of the DTAB/SDBS system the formation of a densely cross-linked silicone material with SiO 3/2 units allowed the nanocapsules to retain the vesicular shape after removal of the template, whereas in the SDBS/DTAB system, the polymer produces capsules which are too smooth to support surfactant lysis. The morphology of the silicone nanocapsules was analyzed using transmission electron microscopy (TEM) and, in some cases, atomic force microscopy (AFM). TEM and AFM reveal discrete hollow particles with a small amount of linked or aggregated hollow silica shells.

Drug‐Induced Micelle‐to‐Vesicle Transition of a Cationic Gemini Surfactant: Potential Applications in Drug Delivery

“…These aggregates exhibit interesting and useful physicochemical properties, for example, rheological and biological properties . Surfactant aggregates that are employed in biotechnology, drug delivery, and the cosmetic and food industries are spherical or ellipsoidal particles, have charged or neutral interfaces, and are classified according to their size, for example, unilamellar, large unilamellar, and multilamellar vesicles . The encapsulation of a drug into vesicles may lead to favorable changes in its pharmacological properties, for instance, better‐controlled drug release and fewer side effects.…”

Biocompatible and thermo-responsive nanocapsule synthesis through vesicle templating

“…On the one hand, vesicles are able to internalize hydrophobic monomers into their surfactant bilayer and therefore, subsequent polymerization could lead to the formation of hollow nanocapsules. 23,24 On the other hand, vesicles have been explored successfully as so templates in the layer-by-layer approach offering different advantages over conventional substrates. Among them, there is the possibility of pre-encapsulation of different substances before the formation of the nanocapsules.…”

Kinetics of thermo-induced micelle-to-vesicle transitions in a catanionic surfactant system investigated by stopped-flow temperature jump

“…On the other hand, catanionic vesicles have been the subject of extensive experimental and theoretical investigations due to their long-term stability and spontaneous formation from mixed surfactant systems. The versatile physicochemical properties of catanionic vesicles have allowed for several application-related studies, such as the preparation of magnetic nanoparticles 39 and hollow spheres 40 and the formation of polymer-vesicle gels and networks. 41 Furthermore, they have been employed for the encapsulation of probe molecules 42 and pharmaceutical drugs, 43 or as gene delivery nanocarriers.…”