Confining the Sol-Gel Reaction at the Water/Oil Interface:Creating Compartmentalized Enzymatic Nano-Organelles for Artificial Cells

Living organisms compartmentalize their catalytic reactions in membranes for increased efficiency and selectivity. To mimic the organelles of eukaryotic cells, we develop a mild approach for in situ encapsulating enzymes in aqueous-core silica nanocapsules. In order to confine the sol-gel reaction at the water/oil interface of miniemulsion, we introduce an aminosilane to the silica precursors, which serves as both catalyst and an amphiphilic anchor that electrostatically assembles with negatively charged hydrolyzed alkoxysilanes at the interface. The semi-permeable shell protects enzymes from proteolytic attack, and allows the transport of reactants and products. The enzyme-carrying nanocapsules, as synthetic nano-organelles, are able to perform cascade reactions when enveloped in a polymer vesicle, mimicking the hierarchically compartmentalized reactions in eukaryotic cells. This in situ encapsulation approach provides a versatile platform for the delivery of biomacromolecules.</p

Tuning polymeric latex functionality via the miniemulsion technique

We describe in this document new advances in miniemulsion polymerizations. We investigated different po-lymerizations in miniemulsion, namely radical, anionic,and condensation polymerizations, in order to obtain different latex functionalities. First, hybrid polymer/ metal latexes were synthesized in direct miniemulsion. Hydrophobic platinum comple-xes were encapsulated in polystyrene particles matrix. These particles were deposited in an ordered mono-layer on silicon substrates due to their monodispersity. Secondly, we synthesized polyamide latexes via different techniques. Anionic polymerization was performed in inverse miniemulsion to give polyamide-6 latexes. The polyamide had a relatively high molecular weight, which was around 36 000 g.mol-1) and had less structural irregularities than the polymer prepared in bulk. Polyamide-6 dispersions in water were prepared under sonication upon addition of polyamide-6 dissolved in a water miscible solvent, to an aqueous solution containing a stabilizer. This novel process combines some features of the solvent displacement process and the miniemulsion technique. Only a small operating win-dow was found to be suitable in order to get stable submicrons particles. Polyamide-6 nanocapsules were prepared by another miniemulsion/ solvent displacement technique. Finally we investigated the synthesis of polymer latexes by polycondensation in miniemulsion. Hollow poly-meric capsules containing a hydrophilic liquid core were obtained in a simple one-pot miniemulsion process without the use of a sacrificial core. The polyurea, polythiourea or polyurethane shells are made by polycon-densation at the interface of the droplets. Capsules loaded with silver nanoparticles were synthesized upon reduction of silver nitrate encapsulated in polyurea shell

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

The miniemulsion technique is a particular case in the family of heterophase polymerizations, which allows the formation of functionalized polymers by polymerization or modification of polymers in stable nanodroplets. We present here an overview of the different polymer syntheses within the miniemulsion droplets as reported in the literature, and of the current trends in the field

Chimie de base, aluminium, sidérurgie : quelle adaptation à la crise ?

Anizon Daniel, Crespy Guy, Remy André. Chimie de base, aluminium, sidérurgie : quelle adaptation à la crise ?. In: Revue d'économie industrielle, vol. 37, 3e trimestre 1986. pp. 74-92

Tuning Polymeric Latex Functionality via The Miniemulsion Technique

2. THEORETICAL SECTION………………………….......………………………….…11 2.1. Heterophase polymerizations……………...…………………………………………...12 2.1.1. The different types of polymerization………………………………………………….12 2.1.1.1. Chain-growth polymerization……...………………………………………………...1

pH-Sensitive Polymer Conjugates for Anticorrosion and Corrosion Sensing

In 2015, the global cost of corrosion in the world was estimated to be around 2.5 trillion dollars and has been continuously increasing. The active protection by corrosion inhibitors is a well-known technique for protecting metals against corrosion. However, one major disadvantage is that corrosion inhibitors can be leached in the environment, even when corrosion does not occur. We design and synthesize smart polymer/corrosion inhibitor conjugates as a new generation of materials for corrosion protection. These materials release inhibitors upon acidification, which may occur either by acidic rain or as a consequence of the metal corrosion process itself. A polymerizable derivative of 8-hydroxyquinoline (8HQ), an effective corrosion inhibitor, is prepared so that it contains acid-labile β-thiopropionate linkages. The monomer is copolymerized with ethyl acrylate, and the obtained functional polymer is processed to form nanoparticles. Under acidic conditions, >95% 8HQ is released from the nanoparticles of the polymer conjugates after 14 days. However, the release was significantly slower under neutral conditions, reaching only 15% during the same period. Additionally, nonconjugated 8HQ can be physically entrapped in the nanoparticles of the polymer conjugates by encapsulation. The nonconjugated 8HQ is then released in less than 30 min so that the coexistence of both conjugated and nonconjugated 8HQ in the nanoparticles allows a release profile, which is a hybrid of sustained and burst releases. Furthermore, the nanoparticles are advantageously used as nanosensors. The 8HQ released from the nanoparticles displays enhanced fluorescence upon chelation with aluminum ions. Therefore, the nanoparticles can be used simultaneously for corrosion sensing and protection

Fabrication of Polymer Ellipsoids by the Electrospinning of Swollen Nanoparticles

Electrospinning is used to deform originally spherical polymer nanoparticles into ellipsoidal nanoparticles. The polymer nanoparticles are swollen and the dispersion is then electrospun. Under certain conditions, the stretching generated in the electrospinning jet is enough to generate elongated nanoparticles embedded in fibers. The formation of the anisotropic particles is observed by stimulated emission depletion (STED) microscopy performed on fluorescent nanoparticles and by electron microscopy measurements on the nanoparticles recovered after removal of the fiber matrix