Search results for "rafting"
showing 10 items of 234 documents
Surface coatings based on polysilsesquioxanes: Grafting-from approach starting from organic polymers
2009
AbstractPoly(methylsilsesquioxane) (PMSSQ) based hybrid materials are promising candidates to produce substrate-independent stable and adherent surface coatings. Usually these materials are synthesized by controlled radical polymerization from inorganic precursors. The presented synthetic pathway in here demonstrates how to graft PMSSQ networks from an endgroup-functionalized organic polymer and thus enlarges the range of accessible inorganic/organic hybrid coating materials.
High-energy radiation processing, a smart approach to obtain PVP-graft-AA nanogels
2014
Abstract Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiate…
Patterning of a Surface Immobilized ATRP Initiator with an Inkjet Printer
2010
A new technique for patterning polymer brushes on the micrometer scale has been developed in which an inkjet printer was used to deposit droplets of acid on a surface-immobilized initiator for atom transfer radical polymerization (ATRP). The acid cleaved an ester bond in the ATRP initiator in a saponification reaction. As a result, the ATRP initiator was rendered inactive. To control the degree of defunctionalization, a new initiator containing a weak ester bond was derived from a tertiary alcohol. Comparison to an established ATRP initiator, derived from a primary alcohol, showed that the novel initiator was defunctionalized with a higher efficiency. Control of the reaction time allowed to…
Saccharide modified silica particles by enzymatic grafting
1997
The surface of silica particles has been chemically modified with oligo- or poly-(α,1→4)-D-glucopyranose (amylose) chains of various length by covalently attaching maltoheptaose derivatives to the solid support and enzymatic polymerization of glucose-1-phosphate with a potato phosphorylase as catalyst. The characterization of the products by solid-state NMR spectroscopy showed an interesting dependence of the linewidth with the grafting density of the glucan chains. The modified silica particles showed chiral discrimination in liquid chromatography.
Branched polymers starting from ethylene-vinyl acetate copolymers
1995
Abstract Polyethylene-graft-poly-2-phenyl-2-oxazoline, polyethylene-graft-poly-2-methyl-2-oxazoline and polyethylenegraft-poly(ethylene oxide) were prepared using poly(ethylene-co-vinyl chloroformate) as macroinitiator or polyfunctional precursor. The vinyl acetate groups of ethylene-vinyl acetate copolymer were hydrolyzed, the corresponding alcohol functions were converted into chloroformate, which in turn was used for grafting of oxazolines. Comb-like polymers with hydrophilic poly(ethylene oxide) grafts with definite length were synthesized as well. The resulting graft copolymers were characterized by GPC, IR, and 1 H-NMR spectroscopy and differential scanning calorimetry.
Linear-Hyperbranched Graft-Copolymers via Grafting-to Strategy Based on Hyperbranched Dendron Analogues and Reactive Ester Polymers
2012
The synthesis of hyperbranched polyglycerol dendron analogues with precisely one focal amino functionality (H2N-hbPG) and their use for the synthesis of linear-hyperbranched graft-copolymers in a grafting-to approach is reported. By use of N,N-dibenzyl tris(hydroxylmethyl) aminomethane as a novel initiator for the ring-opening multibranching polymerization of glycidol, dendron analogues with one focal amino functionality of molecular weights ranging from 500 to 15000 g mol–1 and narrow to moderate polydispersities (Mw/Mn = 1.2–1.9) were synthesized, as confirmed by NMR and SEC. After removal of the benzyl protective groups, the accessibility and selective transformation of the focal amino g…
Gamma radiation induced maleation of polypropylene using supercritical CO 2 : preliminary results
2000
Abstract The charging of maleic anhydride (MA) and dicumyl peroxide (DCP) into polypropylene matrices has been carried out by CO2 in supercritical conditions. The grafting of MA into polymer chains was done through gamma irradiation in CO2 atmosphere (0.1 MPa, 25°C). The grafting was successful and the amount of grafted anhydride was dependent on the amount of MA and DCP charged into the polypropylene matrix. The presence of grafted succinic anhydride was shown by FT-IR spectroscopy and its amount was determined through a calibration curve derived from standard samples. The effect of swelling due to supercritical CO2, maleic anhydride grafting and gamma irradiation on the molecular structur…
Adsorption of Oligomers and Polymers into a Polymer Brush Formed from Grafted Ring Polymers
2013
The interaction of a ring polymer brush with a solution containing oligomers or free linear flexible macromolecules is studied by Monte Carlo simulation, varying the chain length of the free chains, and in selected cases also the lengths of the rings. Two grafting densities are studied, corresponding to semidilute and very concentrated conditions, and a comparison with the corresponding case of brushes formed from grafted linear chains is made. Although the ring polymer linear dimensions in the brushes show an anomalous scaling with ring length, similar to (noncatenated) ring polymer melts, the concentration profiles of oligomers and long macromolecules in ring polymer brushes differ only v…
Interaction Between Polymer Brush-Coated Spherical Nanoparticles: Effect of Solvent Quality
2012
The interaction between two spherical polymer brushes in solvents of variable quality is studied by molecular dynamics simulation and by self-consistent field theory, varying both the radius of the spherical particles and their distance, as well as the grafting density and the chain length of the end-grafted flexible polymer chains. Both the potential of mean force between the particles as a function of their distance is computed, for various choices of the parameters mentioned above, and the structural characteristics are discussed (density profiles, average end-to-end distance of grafted chains, etc.) It is found that for rather short chain lengths and not too large grafting densities, is…
How does the pattern of grafting points influence the structure of one-component and mixed polymer brushes?
2005
Using Monte Carlo simulations of a coarse-grained bead-spring model we study the lateral structure formation of one-component polymer brushes in a bad solvent and of a mixed polymer brush upon increasing the incompatibility of the two species. We compare the morphology of the brush with a regular distribution of grafting points and with a random arrangement. Density or composition fluctuations of the grafting points enhance the formation of irregular structures but randomness prevents the formation of long-range order. Even small fluctuations of the grafting points are sufficient to pin the lateral structures of the brush.