Search results for "polymers"
showing 10 items of 3567 documents
Solvent-tuned ultrasonic synthesis of 2D coordination polymer nanostructures and flakes
2021
Highlights • Combined ultrasound and solvent assisted synthesis of 2D coordination polymers. • Role of interstitial solvent molecules in the delamination of 2D-CPs. • Influence of the sonication time in delamination and nanostructuration processes. • Morphological and supramolecular transformations in 2D-CPs.
Spray freeze drying as an alternative technique for lyophilization of polymeric and lipid-based nanoparticles.
2016
The use of nanoparticles for drug delivery is still restricted by their limited stability when stored in an aqueous medium. Freeze drying is the standard method for long-term storage of colloidal nanoparticles; however the method needs to be elaborated for each formulation. Spray freeze drying (SFD) is proposed here as a promising alternative for lyophilizing colloidal nanoparticles. Different types of polymeric and lipid nanoparticles were prepared and characterized. Afterwards, samples were spray freeze dried by spraying into a column of cold air with a constant concentration of different cryoprotectants, and the frozen spherules were collected for further freeze drying. Similar samples w…
Porous materials applied to biomarker sensing in exhaled breath for monitoring and detecting non-invasive pathologies
2020
International audience; Overview of the use of porous materials for gas sensing to analyze the exhaled breath of patients for disease identification.The quantification of specific gases among thousand of VOCs (Volatile Organic Compounds) present in the human breath at the ppm/ppb level can be used to evidence the presence of diseases in the human body. The detection of these biomarkers in human exhaled breath through a noninvasive approach is an important field of research which is still attracting important attention to this day. A portable device working at room temperature and usable directly on exhaled breath samples is still a challenge requiring a sensing material with high performanc…
Halloysite nanotubes/pluronic nanocomposites for waterlogged archeological wood: thermal stability and X-ray microtomography
2020
Filling a polymer with halloysite nanotubes is considered a promising strategy to generate nanocomposites with tailored physicochemical properties. We have focused our attention on pluronic block copolymer/halloysite nanocomposites prepared by melt blending. The effect of composition on thermal stability and polymer crystallinity was investigated by thermogravimetry and differential scanning calorimetry. Electron microscopy was used to monitor the nanoparticle distribution in the polymeric matrix. The pluronic thermal stability is reduced by the clay nanoparticles. Concerning the polymer crystallinity, it is slightly decreased even if the melting temperature is lowered by halloysite. Furthe…
Optimization of two-step techniques engineered for the preparation of polyamide 6 graphene oxide nanocomposites
2019
Abstract Different processing conditions to achieve polyamide 6 (PA6)-graphene oxide (GO) nanocomposites were investigated. GO was pre-dispersed in PA6 by three different solvent-based methods and, further, melt processed to prepare nanocomposites at two different loading levels, namely 2 and 5 wt.%. The evolution of rheological and mechanical properties was analyzed by investigating eventual changes in the microstructure and polymer crystallinity, aiming at providing a detailed processing-structure-properties relationship for these systems.
Synthesis and catalytic performance in ethylene and 1-octene polymerization of chlorotitanium(IV) silsesquioxane complexes. Effect of increasing liga…
2016
Abstract The series of titanasilsesquioxanes that differ in a way of binding to the transition metal ( via one, two or three oxygen atoms) and type of nonreactive substituents bonded to inorganic oxygen-silicon cage ( i -Bu, Ph, c -C 6 H 11 ) were prepared by reacting of TiCl 4 with 1 eqv. of the silsesquioxane ligand. Upon treatment with an appropriate cocatalyst, all titanium precatalysts are active in ethylene and 1-octene polymerization and produce from low to high molecular weight polyethylenes and moderately ([ mmmm ] = 44–74%) isotactic poly(1-octene)s. The influence of polymerization parameters, type of cocatalyst and the silsesquioxane structure on the catalytic behavior of the tit…
Photocatalytic degradation enhancement in pickering emulsions stabilized by solid particles of bare TiO 2
2019
Pickering emulsions provide a new way to enhance the efficiency of photocatalytic degradation of water-insoluble pollutants. Indeed, the semiconductor solid particles dually act as the photocatalyst and stabilizer of the emulsion droplets whose size dramatically affects the photocatalytic reaction. The present work aims at the validation of this concept by using bare TiO 2 without any surface modification. Nanostructured TiO 2 has been prepared by a simple sol-gel process and characterized by X-ray diffraction, specific surface area analysis, scanning electron microscopy, and diffuse reflectance spectroscopy. The emulsions were prepared by using 1-methylnaphthalene (1-MN) as a model organic…
Curing of an epoxy resin modified with nanoclay monitored by dielectric spectroscopy and rheological measurements
2006
Dielectric and rheological measurements have been performed in “real-time” to follow curing reaction on blends of a diglycidyl ether of bisphenol-A epoxy resin with 4,4-methylene bis(2,6-diethylaniline) hardener and different amounts of organically modified nanoclay (Nanofil 919) as modifier. The effect of the modifier and its amount on the curing reaction, as well as that of the curing temperature has been studied. Changes in molecular mobility in the reaction mixture have been investigated by dielectric relaxation spectroscopy. Evolutions of ionic conductivity and main relaxation have been analyzed and vitrification times have been obtained and compared with those obtained by rheological …
LbL multilayer capsules: recent progress and future outlook for their use in life sciences.
2010
In this review we provide an overview of the recent progress in designing composite polymer capsules based on the Layer-by-Layer (LbL) technology demonstrated so far in material science, focusing on their potential applications in medicine, drug delivery and catalysis. The benefits and limits of current systems are discussed and the perspectives on emerging strategies for designing novel classes of therapeutic vehicles are highlighted. © 2010 The Royal Society of Chemistry.
Asphalt surface mixtures with improved performance using waste polymers via dry and wet processes
2017
"Published online: June 29, 2017"