Manfred L. Hallensleben

Gold Nanoparticles with Covalently Attached Polymer Chains

Living/controlled radical polymerization according to the atom transfer radical polymerization mechanism is a suitable method for the graft-polymerization of nanoparticles. With this method, in which the core nanoparticles remain unchanged, the chain length and therefore the thickness of the polymer shell can be adjusted.

Graft copolymers and composites of poly(methyl methacrylate) and polypyrrole Part II

Abstract Pyrrole (2) was grafted onto a poly(methyl methacrylate) backbone which already contained the pyrrole moiety within via oxidative polymerization with FeCl 3 in nitromethane. The maximum conductivity of films cast from the reaction mixture was about 10 −2 S/cm. The conductivity and the morphology of the graft copolymers 3 depended on several effects which were studied in detail using FT-IR, thermogravimetric analysis, light and scanning electron microscopy.

Oxidative polymerization of poly(2-(N-pyrrolyl)ethyl methacrylate) with iron chloride

Abstract Polymers 2 containing pyrrole in the side group were synthesized by radical polymerization of 2-( N -pyrrolyl)ethyl methacrylate 1 (PEMA). The PEMA units were coupled by oxidation with iron chloride in nitromethane. The polymers reached conductivities about 5 × 10 −5 S/cm upon doping with iodine. The polymers were further characterized using 1 H NMR, IR, gel permeation chromatography and thermogravimetric analysis.

Conductive polymer composites and copolymers of pyrrole and N-vinylcarbazole

Abstract The synthesis of composites and copolymers of pyrrole and N -vinylcarbazole is described. Both insulating and conducting polymers of N -vinylcarbazole are utilized in the electroinitiated polymerization of pyrrole. The influence of coating either of the conducting polymers prior to the other on the percolating threshold is discussed. The initial presence of both monomers in the reaction medium leads to a copolymer, whereas consecutive electrode coatings from the monomer solution yield inhomogeneous composites together with grafts. Characterizations are carried out via FT-IR, DSC, TGA and SEM analyses.

Electrically conductive poly(methyl methacrylate-g-pyrrole) via chemical oxidative polymerization

Abstract Methyl methacrylate (MMA) and 2-bromoethyl methacrylate (BEMA) were copolymerized and the reactivity ratios of the monomers were determined. A pyrrole moiety was introduced into the copolymer via polymer analogous reaction and grafting between this molecule and pyrrole was achieved by chemical oxidative polymerization of pyrrole with iron-(III) chloride. Conductivities of 10 −2 S/cm were measured.

Oxidative polymerization of some N-alkylpyrroles with ferric chloride

Polymers of N-(2-hydroxyethyl)pyrrole (HEP, 1), 2-(N-pyrrolyl)ethyl acetate (PEA, 2) and 2-(N-pyrrolyl)ethyl stearate (3) were synthesized via oxidative polymerization with ferric chloride. Poly(2-(N-pyrrolyl)ethyl acetate) (PPEA, 5) and 2-(N-pyrrolyl)ethyl stearate) (PPES, 6) were partially soluble in organic solvents and transparent films were cast from solution. Selective thermal decomposition of the alkyl chains yielded almost pure polypyrrole moiety. The polymers 4–6 had conductivities of about 10−7−10−5 S/cm upon doping with iodine. The polymers were further characterized using 1H NMR, IR, UV-Vis, differential scanning calorimetry and gel permeation chromatography.

Electrochemical studies on carbazole/pyrrole-copolymers

Abstract We investigated the copolymerization of pyrrole and N-methylpyrrole with N-vinylcarbazole (NVC) and N-ethylcarbazole. The grafting of pyrrole onto poly(N-vinylcarbazole) was examined. The resulting conducting polymers were characterized via cyclic voltammetry and conductivity measurements. Alternating copolymers were synthesized via a novel dipyrrolylcarbazole derivative.

Polypyrrole Grafts Synthesized via Electrochemical Polymerization

Abstract Electrically conducting polypyrrole grafts with poly[(methyl meth-acrylate)-co-(2-(N-pyrrolyl) ethyl methacrylate)] (PMMA-co-PEMA) were synthesized by constant potential electrolysis. Cyclic Voltammetry, DSC, TGA, SEM and elemental analysis were used in order to characterize the free standing films. Conductivities of the polymers were measured by a four-probe technique.

Soluble polycarbazoles and carbazole modified electrodes

Abstract Poly(dicarbazol-9-ylalkane)s and end-capped dicarbazol-9-ylalkanes were studied in order to obtain information about the redox behavior of poly(9-vinylcarbazole). Strong π-dimer effects were observed in the case of 1,3-bis(3,6-diethylcarbazol-9-yl)propane. An additional electron transfer in case of poly(9-vinylcarbazole) at higher potentials (1.7 V vs. Ag/AgCl) was also attributed to interaction between the carbazole tings.

Oxidative polymerization of pyrrole with iron chloride in nitromethane

Abstract Pyrrole was found to polymerize very slowly in nitromethane in the presence of iron(III) chloride to yield a polymer of thin particle size. Addition of water traces increased the rate of reaction about ten times as well as the particle size and the conductivity of polypyrrole formed. The particle size was also affected by reaction temperature. These effects were interpreted in terms of changes in the coordination sphere of the oxidant as well as in reaction kinetics.