Search results for "surface modification"
showing 10 items of 417 documents
Impact of non-functionalized and ionic liquid modified carbon nanotubes on mechanical and thermal properties of ethylene- octene copolymer nanocompos…
2016
In this article the development and characterization of composites made from metallocene based ethylene-octene copolymer (EOC) with 38% octene content, non-modified or modified multi walled carbon nanotubes (MWCNTs), covalently functionalised with long chain hexadecyl moiety imidazolium ionic liquid (IL-f-MWCNTs), is presented. The procedure of MWCNTs functionalization is discussed. In order to obtain a good dispersion of the filler, composites with MWCNTs and IL-f-MWCNTs in the concentration range of 0.5-12 wt.% were made by ultrasonication / thermoplastic mixing method. The results indicated improvement in mechanical properties with increase of the filler content. The methodology of the d…
Functionalization of aliphatic polyesters by nitroxide radical coupling
2014
Functionalized poly(butylene succinate) (PBS) samples were prepared by a post-polymerization method based on the coupling reaction between TEMPO derivatives bearing different functionalities and PBS macroradicals generated by H-abstraction using a peroxide. 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine-1- oxyl (BzO-TEMPO) and 4-(1-naphthoate)-2,2,6,6-tetramethylpiperidine-1-oxyl (NfO-TEMPO), a pro-fluorescent nitroxide, were successfully grafted on PBS, as revealed by MALDI TOF MS and UV-Vis spectroscopy. The functionalization degrees were accurately determined by UV-Vis analysis and confirmed by 1H-NMR spectroscopy. The grafting site was identified by combining theoretical calculations with e…
Enhanced Sieving of C2‐Hydrocarbon from Methane by Fluoro‐Functionalization of In‐MOF with Robust Stability
2021
Developing efficient adsorbent materials is crucial for adsorption and separation to realize the purification of energy source and raw chemicals. Here, we report a novel and robust 3D In-based MOF built up with fluorine-functionalized ligands, QMOF-2F, with improved separation properties of C2-light hydrocarbons over methane at room temperature respect isoreticular non-fluorinated MOF. QMOF-2F shows a remarkable chemical stability in different solvents, including water, and pH (2-12). DFT calculations support the key role of fluorine-functionalization on the improved performance of QMOF-2F.
Photosensitive functionalized surface-modified quantum dots for polymeric structures via two-photon-initiated polymerization technique.
2015
In this paper, the surface modification of CdSe- and CdZnS-based quantum dots (QDs) with a functional silica shell is reported. Functionalized silica shells are prepared by two routes: either by ligand exchange and a modified Stober process or by a miniemulsion process with amphiphilic poly(oxyethylene) nonylphenylether also know as Igepal CO-520 (IG) as oligomeric amphiphile and modified silica precursors. The polymerizable groups on the functionalized silica shell allow covalent bonding to a polymer matrix and prevent demixing during polymerization and crosslinking. This allows the homogeneous incorporation of QDs in a crosslinked polymer matrix. This paper furthermore demonstrates that t…
Cationic copolymers of ?,?-poly-(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and ?,?-polyasparthylhydrazide (PAHy): synthesis and characterization
2000
In the present study the derivatization of two water-soluble synthetic polymers, α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and α,β-polyasparthylhydrazide (PAHy), with glycidyltrimethylammonium chloride (GTA) is described. This reaction permits the introduction of positive charges in the macromolecular chains of PHEA and PAHy in order to make easier the electrostatic interaction with DNA. Different parameters affect the reaction of derivatization, such as GTA concentration and reaction time. PHEA reacts partially and slowly with GTA; on the contrary the reaction of PAHy with GTA is more rapid and extensive. The derivatization of PHEA and PAHy with GTA is a convenient method to introdu…
Versatile ω-end group functionalization of RAFT polymers using functional methane thiosulfonates
2009
Five different polymers, poly[methyl methacrylate] (PMMA), poly[lauryl methacrylate] (PLMA), poly[diethylene glycol methacrylate] (PDEGMA), poly[N-iso-propylacrylamide] (PNIPA), and poly[styrene] (PS) prepared by the RAFT process and thus terminated with dithioesters were aminolyzed in the presence of S-3-butynyl methane thiosulfonate (MTS), which was synthesized in two steps. Analysis of the polymers by 2D NMR, UV–vis absorbance, and gel permeation chromatogra-phy revealed them to quantitatively carry acetylene end groups connected with disul-fide bridges, indicating that functional MTS reagents can be employed for end group functionalization of RAFT polymers. This versatile method is of ad…
Inorganic Polymers: Morphogenic Inorganic Biopolymers for Rapid Prototyping Chain
2013
In recent years, considerable progress has been achieved towards the development of customized scaffold materials, in particular for bone tissue engineering and repair, by the introduction of rapid prototyping or solid freeform fabrication techniques. These new fabrication techniques allow to overcome many problems associated with conventional bone implants, such as inadequate external morphology and internal architecture, porosity and interconnectivity, and low reproducibility. However, the applicability of these new techniques is still hampered by the fact that high processing temperature or a postsintering is often required to increase the mechanical stability of the generated scaffold, …
Isoreticular two-dimensional magnetic coordination polymers prepared through pre-synthetic ligand functionalization
2018
Chemical functionalization is a powerful approach to tailor the physical and chemical properties of two-dimensional (2D) materials, increase their processability and stability, tune their functionalities and, even, create new 2D materials. This is typically achieved through post-synthetic functionalization by anchoring molecules on the surface of an exfoliated 2D crystal, but it inevitably alters the long-range structural order of the material. Here we present a pre-synthetic approach that allows the isolation of crystalline, robust and magnetic functionalized monolayers of coordination polymers. A series of five isostructural layered magnetic coordination polymers based on Fe(ii) centres a…
Solvent-free ruthenium-catalysed triflate coupling as a convenient method for selective azole-o-C-H monoarylation.
2019
Metal-catalysed ortho-directed C–H functionalization usually faces selectivity issues in the competition between mono- and disubstitution processes. We report herein the ruthenium-catalysed N-directed C–H monoarylation of arylpyrazoles with a selectivity of up to 96% or that generally reaches values above 80%. This selectivity is an effect of solvent-free conditions associated with sulfonate reagents, in the absence of frequently used acidic additives.
Silica-Immobilized NHC-Gold(I) Complexes: Versatile Catalysts for the Functionalization of Alkynes under Batch and Continuous Flow Conditions
2017
Immobilized sterically demanding NHC-Au(I) complexes silica-[(IPrR)Au]Cl and silica-[(IAdPrR)Au]Cl are synthesized and characterized. These complexes are suitable catalysts in typical homogeneous Au(I)-catalyzed alkyne reactions such as hydration, hydroamination, hydroarylation, or cycloisomerization. The results obtained with the immobilized catalysts in reactions in batch are comparable to those obtained with their homogeneous counterparts with the advantage of easily recovered and recycled in successive reactions. Their catalytic activity decreases when reused in batch reactions, probably because of crushing that is associated with magnetic stirring. In contrast, these immobilized cataly…