Search results for " modifica"
showing 10 items of 817 documents
Self-assembly of amphiphilic calixarenes and resorcinarenes in water
2010
The calixarenes and resorcinarenes are macrocyclic phenolic molecules that can be modified “a facon” and a wide range of chemical modification strategies have been published over the last 30 years. Because of their remarkable structural properties and their relative ease of chemical modification, they represent excellent and highly versatile bases to design complex building blocks capable of self-assembly and molecular recognition. They have been widely studied for their ability to form supramolecular structures targeting a wide range of applications. The possibility to regio(rim)-selectively modify these macrocycles with different polar and apolar moieties provides synthetic chemists with …
ChemInform Abstract: Self-Assembly of Amphiphilic Calixarenes and Resorcinarenes in Water
2011
The calixarenes and resorcinarenes are macrocyclic phenolic molecules that can be modified “a facon” and a wide range of chemical modification strategies have been published over the last 30 years. Because of their remarkable structural properties and their relative ease of chemical modification, they represent excellent and highly versatile bases to design complex building blocks capable of self-assembly and molecular recognition. They have been widely studied for their ability to form supramolecular structures targeting a wide range of applications. The possibility to regio(rim)-selectively modify these macrocycles with different polar and apolar moieties provides synthetic chemists with …
Preparation of organic monolithic columns in polytetrafluoroethylene tubes for reversed-phase liquid chromatography
2017
[EN] In this work, a method for the preparation and anchoring of polymeric monoliths in a polytetrafluoroethylene (PTFE) tubing as a column housing for microbore HPLC is described. In order to assure a covalent attachment of the monolith to the inner wall of the PTFE tube, a two-step procedure was developed. Two surface etching reagents, a commercial sodium naphthalene solution (Fluoroetch®), or mixtures of H2O2 and H2SO4, were tried and compared. Then, the obtained hydroxyl groups on the PTFE surface were modified by methacryloylation. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification…
A rapid and eco-friendly route to synthesize graphene-doped silica nanohybrids
2016
International audience; In the present study, the possibility to synthesize graphene oxide (GO)-based nanohybrids with pure and O2-doped silica nanoparticles by a rapid and easy hydrothermal process has been explored. The nanohybrids were prepared by varying the type of silica nanoparticles (average diameter 7 nm or 40 nm) and the silica/GO weight ratio. All the materials were fully characterized by spectroscopic and morphological techniques.The experimental results revealed that it is possible to tune the characteristics of the obtained nanohybrids, such as morphology and amount of ester/ether linkages upon varying the preparation parameters, together with the nanosilica's typology and the…
Morphology modification of a polyethylene/clay nanocomposite samples under convergent flow
2009
The morphology of PE/CL nanocomposite samples subjected to convergent flows is studied. Elongational flow – the typical flow involved in spinning and film-blowing processing operations – significantly increases with the reduction of the capillary diameter. The values of the convergent extensional stress (calculated by Cogswell's formula) for the PE/CL systems, for all the adopted capillary geometries, are greater than the calculated values for pure polyethylene. The applied convergent flow, at the entrance of the capillary, is able to change the clay morphology and consequently the final material properties on the PE/CL system with limited affinity between the matrix and organo-modified cla…
Morphology modification in nanofilled polymer based systems upon shear and elongational flow
2011
Morphology modification of polymer-filled nanocomposites subjected to non-isothermal elongational flow
2010
A new route for the preparation of flexible skin–core poly(ethylene-co-acrylic acid)/polyaniline functional hybrids
2011
Abstract Surface modification of polymeric films is a way to obtain final products with high performance for many specific and ad hoc tailored applications, e.g. in functional packaging, tissue engineering or (bio)sensing. The present work reports, for the first time, on the design and development of surface modified ethylene–acrylic acid copolymer (EAA) films with polyaniline (PANI), with the aim of inducing electrical conductivity and potentially enable the electronic control of a range of physical and chemical properties of the film surface, via a new “grafting from” approach. In particular, we demonstrate that PANI was successfully polymerized and covalently grafted onto flexible EAA su…
Effect of the nanotube aspect ratio and surface functionalization on the morphology and properties of multiwalled carbon nanotube polyamide-based fib…
2013
In this study, the effect of the carbon nanotube (CNT) aspect ratio and surface functionalization on the mechanical behavior and morphological changes of polyamide (PA)-based fibers was investigated. Composites were prepared by the melt blending of CNTs with PA, and at a later time, the fibers were prepared by melt spinning and cold drawing. A reinforcement effect was noticed for all of the CNTs samples, and the increase in the mechanical properties and dimensional stability was more pronounced for highly oriented filaments. When the elongational flow was increased, the orientation of CNTs along the fiber direction was observed, but the nanotube alignment was much more difficult for CNTs wi…
Small genomes and the difficulty to define minimal translation and metabolic machineries
2015
The notion of minimal life has sparked the interest of scientists in different fields, ranging from the origin-of-life research to biotechnology-oriented synthetic biology. Whether the interest is focused on the emergence of protocells out of prebiotic systems or the design of a cell chassis ready to incorporate new devices and functions, proposing minimal combinations of genes for life is not a trivial task. Using comparative genomics and biochemistry of endosymbionts (i.e., intracellular mutualistic symbionts) and intracellular parasites, a decade ago we proposed the core of a minimal gene set for a simple heterotrophic cell adapted to a chemically complex environment. In this work, we di…