Nanoporous thin films from ionically connected diblock copolymers

in European Polymer Journal (2012), 48(5), 940-944

An ionically connected polystyrene-block-poly(ethylene oxide) diblock copolymer (PS−+PEO) has been prepared by blending a PEO block functionalized by a dimethylamino group at one extremity with a sulfonic ... [more ▼]

An ionically connected polystyrene-block-poly(ethylene oxide) diblock copolymer (PS−+PEO) has been prepared by blending a PEO block functionalized by a dimethylamino group at one extremity with a sulfonic acid terminated PS block. Proton transfer occurs from the sulfonic acid to the dimethylamino group, resulting in the formation of an ion pair acting as a junction between the two polymer blocks. This copolymer was further used to prepare thin films with a cylindrical morphology consisting of PEO cylinders embedded in a PS matrix and oriented perpendicularly to the film surface. Nanoporous thin films with sulfonate groups on the pore walls have been finally obtained after solvent extraction of the PEO microphases. The presence of those sulfonate groups was evidenced by grafting a positively charged fluorescent dye on the pore walls. [less ▲]

Surfactant-free synthesis of amphiphilic poly(ethylene oxide)-b-poly(n-butyl acrylate) copolymers by ab initio batch emulsion polymerization under RAFT control

Poster (2008, August 19)

Mannosylated poly(ethylene oxide)-b-Poly(epsilon-caprolactone) diblock copolymers: Synthesis, characterization, and interaction with a bacterial lectin

in Biomacromolecules (2007), 8(9), 2717-2725

A novel bioeliminable amphiphilic poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) diblock copolymer end-capped by a mannose residue was synthesized by sequential controlled polymerization of ... [more ▼]

A novel bioeliminable amphiphilic poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) diblock copolymer end-capped by a mannose residue was synthesized by sequential controlled polymerization of ethylene oxide and epsilon-caprolactone, followed by the coupling of a reactive mannose derivative to the PEO chain end. The anionic polymerization of ethylene oxide was first initiated by potassium 2-dimethylaminoethanolate. The ring-opening polymerization of epsilon-caprolactone was then initiated by the omega-hydroxy end-group of PEO previously converted into an Al alkoxide. Finally, the saccharidic end-group was attached by quaternization of the tertiary amine (alpha-end-group of the PEO-b-PCL with a brominated mannose derivative. The copolymer was fully characterized in terms of chemical composition and purity by high-resolution NMR spectroscopy and size exclusion chromatography. Furthermore, measurements with a pendant drop tensiometer showed that both the mannosylated copolymer and the non-mannosylated counterpart significantly decreased the dichloromethane/water interfacial tension. Moreover, these amphiphilic copolymers formed monodisperse spherical micelles in water with an average diameter of similar to 11 nin as measured by dynamic light scattering and cryo-transmission electron microscopy. The availability of mannose as a specific recognition site at the surface of the micelles was proved by isothermal titration microcalorimetry (ITC), using the BclA lectin (from Burkholderia cenocepacia), which interacts selectively with a-D-mannopyranoside derivatives. The thermodynamic parameters of the lectin/mannose interaction were extracted from the ITC data. These colloidal systems have great potential for drug targeting and vaccine delivery systems. [less ▲]

Synthesis of novel amphiphilic and pH-sensitive ABC miktoarm star terpolymers

in Macromolecules (2006), 39(17), 5652-5656

Novel amphiphilic ABC miktoarm star terpolymers were synthesized that consist of hydrophilic poly( ethylene oxide) (PEO), hydrophobic poly(is an element of-caprolactone) (PCL), and pH-sensitive poly(2 ... [more ▼]

Novel amphiphilic ABC miktoarm star terpolymers were synthesized that consist of hydrophilic poly( ethylene oxide) (PEO), hydrophobic poly(is an element of-caprolactone) (PCL), and pH-sensitive poly(2-vinylpyridine) (P2VP), thus a water-soluble block upon protonation. In the first step, poly( ethylene oxide monomethyl ether) (MPEO) was capped by one omega-epoxy end group by reaction of the original hydroxy end group with epichlorohydrin. MPEO-b-P2VP diblock copolymers were prepared by nucleophilic addition of living P2VP-Li+ chains onto the epoxy group of MPEO's. Finally, the hydroxy group formed at the junction of the MPEO and P2VP blocks was used to initiate the ring-opening polymerization of is an element of-caprolactone in the presence of tin octoate. The ABC starshaped triblocks were characterized by H-1 NMR spectroscopy and size exclusion chromatography. [less ▲]

Simple method for the stretching and alignment of single adsorbed synthetic polycations

in Small : Nano Micro (2006), 2(7), 910-916

Spin-coating of isolated positively charged macromolecules onto mica in the presence of octylamine was found to be a simple and general method of stretching and aligning the macromolecular chains. The ... [more ▼]

Spin-coating of isolated positively charged macromolecules onto mica in the presence of octylamine was found to be a simple and general method of stretching and aligning the macromolecular chains. The contour length and molar mass for the stretched macromolecules can be directly measured by atomic force microscopy, which makes this method a very useful analytical tool. Moreover, the molecular height is increased by codeposition with octylamine, which drastically improves the molecular resolution and allows even ultrathin polycations to be visualized. The reason for the key role of the octylamine is found in the formation of an ultrathin liquidlike alkylamine film, which reduces the surface energy of mica and weakens the interactions between the surface and the charged macromolecules. [less ▲]

Molecular weight determination by visualization of stretched polycation molecules

in PMSE Preprints (2006), 95

Synthesis and deposition of water-dispersed prussian blue nanocrystals on polymers and CNTs

in Progress in Colloid & Polymer Science (2006), 132

Nanoparticles can be used for decoration and functionalization of single polymer molecules that have been adsorbed to a solid substrate. Initial attempts to prepare Prussian Blue nanoclusters by a layer ... [more ▼]

Nanoparticles can be used for decoration and functionalization of single polymer molecules that have been adsorbed to a solid substrate. Initial attempts to prepare Prussian Blue nanoclusters by a layer-by-layer deposition technique of hexacyanoferrate anions and ferric cations onto isolated polycation chains in water failed because of the desorption of the first layer upon deposition of the next one. A simple method for the preparation of charge-stabilized Prussian Blue nanoparticles of readily adjustable size is reported. Prussian Blue nanoparticles have been purified by addition of non-solvents and redispersed in water without aggregation. Thus formed Prussian Blue nanoparticles are crystalline and display a long-range ferromagnetic ordering at 5.1 K. Prussian Blue nanoparticles were selectively deposited along single polycation molecules to form a one-dimensional array or were attached to the surface of carbon nanotubes (CNTs) functionalized with poly2-vinylpyridine (P2VP). These nanoparticle-based nanostructures might be useful materials for manufacture of electrooptical devices, or mechanically robust ion-sieving membranes. [less ▲]

An easy and economically viable route for the decoration of carbon nanotubes by magnetite nanoparticles, and their orientation in a magnetic field

in Chemical Communications (2005), (36), 4532-4533

A simple, cheap and tunable approach for the decoration of carbon nanotubes by magnetite nanoparticles and their orientation in a magnetic field is reported.

A novel strategy for the dispersion, selective deposition and decoration of carbon nanotubes

Poster (2005, May 11)