Search results for "Radical polymerization"
showing 10 items of 184 documents
Surfactant-Free Emulsion Polymerization of Various Methacrylates: Towards Monodisperse Colloids for Polymer Opals
2004
A systematic investigation of the surfactant-free emulsion polymerization (SFEP) on three different methacrylates (MMA, tert-butyl methacrylate and 2,2,2-trifluoro ethyl methacrylate) is described to obtain monodisperse colloids for the preparation of artificial polymer opals. The experimental results are in agreement with a model, in which seed particles are formed very early during the polymerization process. The particles are formed very early during the polymerization process. The particles grow afterwards into the colloids until all monomer is consumed. This gives rise to a linear relationship between the volume of the colloids and the ratio of monomer to water in the reaction batch. T…
Macromonomers on the basis of 2-phenyl-2-oxazoline
1988
By initiation of the ring-opening polymerization of 2-phenyl-2-oxazoline (1) with p-iodomethylstyrene a macromonomer with a styrene end-group (2) is obtained. The degree of polymerization was varied between 10 and 16. The radical copolymerization of 2 with styrene is described. 1 forms with methyl triflate a very stable oxazolinium salt which is a good initiator for the bulk polymerization of 1 at temperatures of 50–70°C. It was conclusively proved that under these conditions the polymerization proceeds by a living mechanism. By termination with N, N-dimethylaminopropylmeth-acrylamide a macromonomer (5) was obtained. 5 can be radically homopolymerized. This comb-like polymer 6 has the typic…
RAFT Polymerization of Pentafluorophenyl Methacrylate: Preparation of Reactive Linear Diblock Copolymers
2005
Reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) was carried out in the presence of cumyldithiobenzoate and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid, respectively. These chain transfer agents with 2,2'-azoisobutyronitrile (AIBN) as initiator yielded the active ester polymer poly(PFMA) with M n up to 17000 g . mol -1 and low polydispersity index (M w /M n <1.2). Kinetic analysis using 19 F NMR spectroscopy and gel permeation chromatography (GPC) measurements showed controlled polymerization behavior for both chain transfer agents. Successful preparation of linear diblock copolymers consisting of an active ester block and m…
Amphipolar Core−Shell Cylindrical Brushes as Templates for the Formation of Gold Clusters and Nanowires
2002
Methacryloyl end-functionalized block copolymers consisting of styrene and vinyl-2-pyridine were polymerized to poly(block co-macromonomer)s with a much higher main chain than side chain degree of ...
Effect of interfacial area on heterogeneous free radical grafting of vinyl monomers in supercritical carbon dioxide: Grafting of acrylic acid on poly…
2014
The role of the polymer interfacial area on free radical grafting of acrylic acid (AA) onto poly(vinylidenefluoride) (PVDF) was studied at 65°C using supercritical carbon dioxide (scCO2) as a solvent and swelling agent, benzoylperoxide (BPO) as chemical initiator and PVDF nanoparticles as polymer matrix. Under adopted conditions PVDF particles do not melt neither dissolve in the reaction medium and FTIR analyses performed on carefully washed nanoparticles confirmed the achievement of high grafting levels. The mass fraction of grafted AA increased with the grafting time and the BPO concentration while it decreased when the density of the fluid phase was enhanced. Collected results suggest th…
Synthesis and degradation of poly (2-hydroxyethyl methacrylate)-graft-poly (ε-caprolactone) copolymers
2004
Abstract Poly (e-caprolactone) macromonomers carrying a methacryloyl end groups were synthesized using different lanthanide derivatives as catalysts, and characterized by SEC and 1 H NMR. Hydrophilic–hydrophobic copolymers from macromonomers and 2-hydroxyethyl methacrylate (HEMA) were obtained by solution free radical polymerization. Depending on the feed ratio of the two components, different copolymer structures were obtained. The expected graft structure of the copolymers was confirmed by 1 H NMR. Thermal properties of the copolymers were determined by DSC and TGA. Hydrolytic and enzymatic degradations of the materials were performed. Poly (2-hydroxyethyl methacrylate)- graft -poly (e-ca…
HPMA Based Amphiphilic Copolymers Mediate Central Nervous Effects of Domperidone
2011
In this study we give evidence that domperidone encapsulated into amphiphilic p(HPMA)-co-p(laurylmethacrylate) (LMA) copolymer aggregates is able to cross the blood-brain barrier, since it affected motor behaviour in animals, which is a sensitive measure for CNS actions. Carefully designed copolymers based on the clinically approved p(HPMA) were selected and synthesized by a combination of controlled radical polymerization and post-polymerization modification. The hydrodynamic radii (R(h) ) of amphiphilic p(HPMA)-co-p(LMA) alone and loaded with domperidone were determined by fluorescence correlation spectroscopy.
Metal–organic covalent network chemical vapor deposition for gas separation
2016
The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal–organic covalent network (MOCN) layers. The resulting hyper-thin and flexible MOCN layers exhibit outstanding gas-separation performances for multiple gas pairs.
Fast Polymeric Functionalization Approach for the Covalent Coating of MoS2 Layers
2021
We present the covalent coating of chemically exfoliated molybdenum disulfide (MoS2) based on the polymerization of functional acryl molecules. The method relies on the efficient diazonium anchoring reaction to provoke the in situ radical polymerization and covalent adhesion of functional coatings. In particular, we successfully implement hydrophobicity on the exfoliated MoS2 in a direct, fast, and quantitative synthetic approach. The covalent functionalization is proved by multiple techniques including X-ray photoelectron spectroscopy and TGA-MS. This approach represents a simple and general protocol to reach dense and homogeneous functional coatings on 2D materials.