Encapsulation by interfacial polycondensation. II. The membrane wall structure and the rate of the wall growth

Polyelectrolyte hydrogel capsules as stabilizers for reconfigurable complex emulsions

Polyelectrolyte capsules stabilize biphasic oil droplets while preserving droplet reconfigurability in the presence of surfactants.

Technological solutions for encapsulation

Encapsulation offers broad scope of applications. It can be used to deliver almost everything from advanced drugs to unique consumer sensory experiences; it could be also employed as a protection system or a sensing material. This cutting-edge technology undergoes rapid growth in both academic and industrial conditions. Research in this matter is continuing to find a new application of microcapsules as well as to improve the methods of their fabrication. Therefore, in this review, we focus on the art of the encapsulation technology to provide the readers with a comprehensive and in-depth understanding of up-to-day development of microcapsule preparation methods. Our goal is to help identify the major encapsulation processes and by doing so maximize the potential value of ongoing research efforts.

Nano-capsules of amphiphilic poly(ethylene glycol)-block-poly(bisphenol A carbonate) copolymers via thermodynamic entrapment

Fast and simple preparation of nano-capsules by water addition to poly(ethylene glycol)-block-poly(bisphenol A carbonate) copolymers in THF.

Simulation of thin film membranes formed by interfacial polymerization

Interfacial polymerization is widely used today for the production of ultrathin films for encapsulation, chemical separations, and desalination. Polyamide films, in particular, are employed in manufacturing of reverse osmosis and nanofiltration membranes. While these materials show excellent salt rejection, they have rather low water permeability, both properties that apparently stem from the rigid cross-linked structure. An increasing amount of experimental research on membranes of different chemistries and membrane characterization suggests the importance of other factors (such as unreacted functional groups and surface roughness) in determining membrane performance. We developed a molecular simulation model to qualitatively study the effects of various synthesis conditions on membrane performance, in terms of its estimated porosity and permeability. The model is of an interfacial aggregation process of two types of functional monomers. Film growth with time and structural characteristics of the final film are compared with predictions of existing theories and experimental observations.

Polymeric microcapsules for synthetic applications

For decades scientists have been working on closed systems for transportation, catalysis and protection, which are inspired by natural cells. Only recently polymer based systems have emerged for these systems, since they are more robust, give protection from the environment and give a more stable membrane. Various methods have been developed to prepare polymer based capsules. They can be made by self-assembly, templating, in situ polymerization or precipitation. Their application has been explored in various areas e.g. drug delivery, diagnostics, sensors and nano reactors. Considering the output in this field has substantially grown, more developments can be expected from this latter application.

Polyamide microcapsules containing jojoba oil prepared by inter-facial polymerization

Jojoba oil containing polyamide microcapsules having diameter of approximately 5 microm were prepared by inter-facial polycondensation by direct method (oil-in-water). Qualitative effects of both the formulation and the process parameters on microcapsules characteristics were investigated by SEM observations. Morphological analysis showed the dependence of the external membrane compactness on the chemical nature of the water-soluble polyamine and the oil-soluble acid polychloride: 1,6-hexamethylenediamine (HMDA) and terephthaloyl dichloride (TDC) were found to favour the production of smooth and dense surfaces. The use of ultrasonic irradiations during the dispersion step to get a further reduction of microcapsules size was also evaluated.

Formation of liquid core-polymer shell microcapsules

Polymer shell microcapsules with liquid cores are used in a wide variety of industries, from food and flavour protection to inkless paper. There is a number of production methods, each with different characteristics and this article reviews a number of them. The methods considered are colloidosome formation, polymer precipitation by phase separation, polycondensation interfacial polymerisation, layer-by-layer polyelectrolyte deposition, polymer growth by surface polymerisation and copolymer vesicle formation. Each production method is described and the relative strength of each is outlined.

Theoretical model of interfacial polymerization

We present a theoretical description for the creation of a thin polymeric layer through the interfacial polymerization of two immiscible, low molecular weight liquids. The theory specifically takes into account the effects of polydispersity on the formation of the polymer film at the liquid-liquid interface. Consequently, we can describe the structure of the growing film and the molecular weight distribution of the resultant polymer chains. We focus on a model system where alternating AB copolymers are formed at the interface between phase-separated, low molecular weight species A and B. It is assumed that any A(B) unit can reversibly attach to any available B(A) unit or B(A)-ended chain. The formation of the copolymer layer is described by a system of reaction-diffusion equations, which detail the chemical evolution and diffusive dynamics of the polydisperse mixture of AB copolymers around the interface, and the evolution of the interface itself. Using this model, we determine the effects of the chemical reaction rates and the initial conditions on the kinetics of forming the AB copolymer layer and the structure of this film.

Complexing capsules--metal extraction and modeling of ion transfer

Polyamide complexing capsules containing a poly(acrylic acid) gel are synthesized by a two steps polymerization process with various diameters (10 microm for microcaps or 200 microm for mcaps). A cationic exchange between gel carboxylic functions and metal ions is realized. Extraction and stripping measurements show that the composition of the capsule membrane doesn't hinder the mass transfer. A model, taking account only of the diffusion in the gel phase, is studied.