Imparting antifouling properties of poly(2-hydroxyethyl methacrylate) hydrogels by grafting poly(oligoethylene glycol methyl ether acrylate)

in Langmuir (2008), 24(13), 6649-6658

The antifouling properties of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogels were improved by the surface grafting of a brush of poly(oligoethylene glycol methyl ether acrylate) [poly ... [more ▼]

The antifouling properties of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogels were improved by the surface grafting of a brush of poly(oligoethylene glycol methyl ether acrylate) [poly(OEGA)]. The atom-transfer radical polymerization (ATRP) of OEGA (degree of polymerization = 8) was initiated from the preactivated surface of the hydrogel under mild conditions, thus in water at 25 °C. The catalytic system was optimized on the basis of two ligands [1,1,4,7,10,10-hexamethyl-triethylenetetramine (HMTETA) or tris[2-(dimethylamino)ethyl]amine (Me6TREN)] and two copper salts (CuIBr or CuICl). Faster polymerization was observed for the Me6TREN/CuIBr combination. The chemical composition and morphology of the coated surface were analyzed by X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements by the water droplet and captive bubble methods, scanning electron microscopy, and environmental scanning electron microscopy. The hydrophilicity of the surface increased with the molar mass of the grafted poly(OEGA) chains, and the surface modifications were reported in parallel. The antifouling properties of the coatings were tested by in vitro protein adsorption and cell adhesion tests, with green fluorescent protein, β-lactamase, and lens epithelial cells, as model proteins and model cells, respectively. The grafted poly(OEGA) brush decreased the nonspecific protein adsorption and imparted high cell repellency to the hydrogel surface. [less ▲]

Toward protein and cell repellent properties by surface modification of intraocular lenses

Poster (2008, June 23)

Polymer composite material structures comprising carbon based conductive loads

Patent (2008)

The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 to 6 wt% carbon based ... [more ▼]

The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 to 6 wt% carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loads. The present invention furthermore provides a method for forming a polymer composite material structure comprising carbon based conductive loads. [less ▲]

Surface coating of hydrogel intraocular lenses toward resistance to posterior capsular opacification

Conference (2008, May 23)

Polyolefin matrixes with permanent antibacterial activity: preparation, antibacterial activity, and action mode of the active species

Poster (2008, May 22)

Effect of the addition of nanoclay on the extrusion foaming of poly(styrene-co-acrylonitrile) with supercritical carbon dioxide

Conference (2008, May 22)

Active Substance Delivery System Comprising A Hydrogel Matrix And Microcarriers

Patent (2008)

Synthesis of novel functional aliphatic polyesters by association of ring-opening polymerization and click chemistry

Conference (2008, April 09)

Nowadays, biodegradable and biocompatible aliphatic polyesters are widely used as environmentally friendly thermoplastics and biomaterials. Nevertheless, the absence of any functional group along the ... [more ▼]

Nowadays, biodegradable and biocompatible aliphatic polyesters are widely used as environmentally friendly thermoplastics and biomaterials. Nevertheless, the absence of any functional group along the chain is a severe limitation for the development of new applications. Very recently, it was reported by Emrick et al. and by us that copper(I)-mediated 1,3-dipolar Huisgen's cycloaddition of alkynes and azides, the most widely used “click” reaction in the frame of macromolecular engineering, is very efficient to derivatize aliphatic polyesters. Due to the tolerance for many functional groups, cumbersome protection and deprotection steps are not needed. One main advantage of copper(I)-mediated Huisgen's cycloaddition compared to other reactions previously used to derivatize aliphatic polyesters relies on the mildness of the experimental conditions, which results in limited degradation. Our most recent results dealing with the combination of “click” chemistry and ring-opening polymerization towards functional PCL and PLA, networks, graft and hyperbranched copolymers will be highlighted. [less ▲]

Core-Shell-Corona Micelles by PS-b-P2VP-b-PEO Copolymers: Focus on the Water-Induced Micellization Process

in Langmuir (2008), 24(7), 3009-3015

It is now well established that amphiphilic PS-b-P2VP-b-PEO linear triblock copolymers can form multilayered assemblies, thus core-shell-corona (CSC) micelles, in water. Micellization is triggered by ... [more ▼]

It is now well established that amphiphilic PS-b-P2VP-b-PEO linear triblock copolymers can form multilayered assemblies, thus core-shell-corona (CSC) micelles, in water. Micellization is triggered by addition of a small amount of water into a dilute solution of the PS-b-P2VP-b-PEO copolymer in a non-selective organic solvent. However, the phenomena that take place at the very beginning of this process are poorly documented. How these copolymer chains are perturbed by addition of water was investigated in this work by light and neutron scattering techniques and transmission electron microscopy. It was accordingly possible to determine the critical water concentration (CWC), the compactness of the nano-objects in solution, their number of aggregation, and their hydrodynamic diameter at each step of the micellization process. [less ▲]

Mechanistic Insights into the Cobalt-Mediated Radical Polymerization (CMRP) of Vinyl Acetate with Cobalt(Iii) Adducts as Initiators

in Chemistry : A European Journal (2008), 14(13), 4046-4059

Over the past few years, cobalt-mediated radical polymerization (CMRP) has proved efficient in controlling the radical polymerization of very reactive monomers, such as vinyl acetate (VAc). However, the ... [more ▼]

Over the past few years, cobalt-mediated radical polymerization (CMRP) has proved efficient in controlling the radical polymerization of very reactive monomers, such as vinyl acetate (VAc). However, the reason for this success and the intimate mechanism remained basically speculative. Herein, two mechanisms are shown to coexist: the reversible termination of the growing poly(vinyl acetate) chains by the Co(acac)(2) complex (acac: acetylacetonato), and a degenerative chain-transfer process. The importance of one contribution over the other strongly depends on the polymerization conditions, including complexation of cobalt by ligands, such as water and pyridine. This significant progress in the CMRP mechanism relies on the isolation and characterization of the very first cobalt adducts formed in the polymerization medium and their use as CMRP initiators. The structure proposed for these adducts was supported by DFT calculations. Beyond the control of the VAc polymerization, which is the best ever achieved by CMRP, extension to other monomers and substantial progress in macromolecular engineering are now realistic forecasts. [less ▲]