S. Samal

Syntheses and properties of macromolecular fullerenes, a review

The recent progress and prospects of macromolecular fullerenes with respect to their syntheses and properties are compiled and discussed. The variety of macrofullerenes with emphasis on C60 and C70 is presented and synthetic concepts of polymer derivatives of fullerenes are outlined. After a concise consideration of the fundamentals of fullerene reactivity, both major types of fullerene-containing polymers, main-chain and side-chain polymers, together with special types, such as telechelic, macrocyclic, dendrimeric and star-shaped fullerene materials, are covered. Also, the synthesis of fullerene-containing copolymers via radical polyreactions and preparative aspects of surface-attached fullerenes are described. The properties of the macromolecular fullerene derivatives are discussed in view of their structure and application. Finally, the role of macrofullerenes for new materials or their precursors is elucidated. © 1999 Society of Chemical Industry

Chelating resins. III. Synthesis, characterization, and capacity studies of formaldehyde-condensed phenolic schiff bases derived from 1,2-diamines and hydroxy benzaldehydes

Schiff bases of hydroxy benzaldehydes with aliphatic and aromatic 1,2-diamines were re-sinified in HCHO in alkaline media. These resins were found to form complexes readily with Cu(II), Co(II), and Ni(II). The materials were characterized by infrared, 1H-NMR, UV-visible (UV-vis) spectral studies, and thermogravimetric analyses. The phenolic oxygen and the azomethene nitrogen were the ligating sites, one or more lattice positions in polychelates being occupied by water molecules. 1H-NMR provided evidence for bridging methylene and terminal methylol groups. The UV-vis spectra showed weak absorptions in the d—d transition range. Capacity studies of the resins indicated metal loading up to 70% at room temperature in an appropriate pH of the salt solutions. The effects of contact time, particle size of the sorbents, resin quantity, and pH on the adsorption characteristics were studied. In the pH range 3-8, the resins derived from the structurally rigid Schiff bases exhibited higher capacity for the metal ions than the resins derived from structurally flexible Schiff bases. Kinetic parameters computed from the thermogravimetric data indicated the resins to be more stable than the corresponding polychelates.

Photoinduced graft copolymerization: X—Graft copolymerization of methyl methacrylate onto wool using isoquinoline-sulphur dioxide charge-transfer complex as the initiator

Abstract The photoinduced graft copolymerization of methyl methacrylate onto wool fibre was investigated using an isoquinoline-sulphur dioxide charge-transfer complex as the initiator. The percentage of graft yield increases with increasing concentration of the monomer and the initiator. The reaction was carried out at three different concentrations and the overall activation energy was computed. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. A suitable kinetic scheme has been suggested.

Grafting Vinyl Monomers onto Chemically Modified Wool Fibers: Graft Copolymerization of Methyl Methacrylate onto Reduced Wool Fibers Using Acetylacetonate Complex of Manganese(III)

Abstract The graft copolymerization of methyl methacrylate (MMA) onto reduced Indian Chokla wool fibers was studied in aqueous solution using the acetylacetonato complex of Mn(III) as the initiator. Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, acidity of the medium, the temperature, and the reaction medium. It is observed that the graft yield increases with increasing concentration of the chelate and acid and with increasing temperature. There is an increase in graft yield within a certain concentration range of the monomer, after which it falls. The grafting is considerably influenced by changing the solvent composition of the reaction medium. A comparative study reveals that oxidized and reduced wools are better substrates than untreated and other chemically modified wools. The effect of various monomers on graft yield is investigated. MMA is found to be a most active monomer compared to other vinyl...

Grafting Vinyl Monomers onto Wool Fibers. X. Graft Copolymerization of Methyl Methacrylate onto Wool Using Acetylacetonato Complex of Manganese(lII)

Abstract The graft copolymerization of methyl methacrylate onto wool fibers was investigated in aqueous solution using the acetylacetonato complex of manganese(III). The rate of grafting was determined by varying the monomer, the complex, the temperature, the acidity of the medium, the nature of the wool, and the reaction medium. The graft yield increases with increasing monomer and complex concentrations. The graft yield also increases with increasing temperature. The grafting is considerably influenced by chemical modification of wool prior to grafting. A suitable mechanism has been proposed and a rate equation has been derived.

Synthesis, characterization, and metal-ion uptake studies of chelating resins derived from formaldehyde-condensed azodyes of aniline and 4,4'-diaminodiphenylmethane coupled with phenol/resorcinol

The diazonium salts of aniline and 4,4′-diaminodiphenylmethane coupled with phenol and resorcinol were condensed with formaldehyde in alkaline media to yield polymeric resins. These polymers were found to readily react with metal ions like Cu2+ and UO, forming polychelates. The azodyes, resins, and polychelates were characterized by several instrumental techniques such as elemental analysis, FTIR, 1H-NMR, GPC, XRD, TG–DTG, and DSC studies. The chelating capacity of the resins toward Cu2+ and UO ions was studied by spectrophotometry. The extent of metal loading of the resins was studied by varying the time of contact, metal-ion concentration, and pH of the reaction medium. The alkali and alkaline earth metal ions had little effect on the metal-ion uptake behavior of the resins. The resin derived from the azodye of 4,4′-diaminodiphenylmethane was found to be more efficient in removing the metal ions from solution than were the resins from aniline. The optimum conditions for effective separation of Cu2+ from UO were determined.

A comparative study on metal ion uptake behavior of chelating resins derived from the formaldehyde-condensed phenolic Schiff bases of 4,4′-diaminodiphenylsulfone and hydroxybenzaldehydes

Three reactive and functional polymers were synthesized by reacting formaldehyde with the phenolic Schiff bases derived from 4,4′-diaminodiphenylsulfone and o-, m-, and p-hydroxybenzaldehydes, respectively. The metal ion uptake behavior of these resins towards Cu2+, Ni2+, Co2+, and UO2 2+ ions in dilute aqueous media was studied. The optimum conditions for the absorption of metal ions were determined by varying the various parameters like contact time, size of the sorbents, concentration of the metal ion solutions, and the pH of the reaction medium. Suitable conditions were ascertained for preferential adsorption of the above metal ions from the salt solutions containing other interfering ions such as Na+, K+, and Mg2+. Presence of these alkali and alkaline earth metal ions in the salt solutions did not affect the adsorption behavior of the resins. It was observed that the structural features of the resins have a profound effect on the uptake characteristics. The position of the OH group present in the meta position with respect to the imine nitrogen atom in the resin, demonstrated a significant influence on the extent of metal ion adsorption by the resin. Out of the three resins reported here, the resin derived from the Schiff base of m-hydroxybenzaldehyde-4,4′-diaminodiphenylsulfone showed higher efficiency in uptake of metal ions from the solutions than the corresponding resins derived from the Schiff bases of o- and p-hydroxybenzaldehyde-4,4′-diaminodiphenylsulfone.

Photoinduced graft copolymerization: XII—Graft copolymerization of methyl methacrylate onto wool using peroxydiphosphate as the photoinitiator

Abstract The photoinduced graft copolymerization of methyl methacrylate onto wool fibers was investigated using peroxydiphosphate as the initiator. Up to a certain concentration of the monomer and the initiator the graft yield increased beyond that concentration a decreasing trend was observed. The reaction was carried out at four different temperatures and the energy of activation was evaluated. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. A suitable reaction scheme has been proposed.

Grafting Vinyl Monomers onto Silk Fibers: Graft Copolymerization of Vinyl Monomers onto Silk Using the Vanadyl Acetylacetonate Complex

Abstract The graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10−5 mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases with increasing concentration of HCIO4 and with increasing temperature. Inhibitors like picryl chloride and hydroquinone significantly decrease the extent of grafting. Alcoholic solvents at a solvents/water ration of 10:90 seem to constitute the most favorable medium for grafting. A suitable reaction scheme has been proposed, and the activation energy calculate...

Grafting vinyl monomers onto wool fibers: graft copolymerization of methyl methacrylate onto wool using ferric acetylacetonate complex

Abstract The graft copolymerization of methyl methacrylate (MMA) onto native and reduced Indian Chokla wool fibers was studied in aqueous solution using an acetylacetonate complex of Fe(III). Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, and the solvent composition of the reaction medium. The graft yield increases with increasing concentration of the initiator and with increasing temperature. An increase of monomer concentration up to 0.5634 mol/L and of the HClO4 concentration up to 0.01 mol/L increases the graft yield. Reduced and oxidized wools were found to be better substrates than untreated, esterified, cross-linked, and trinitrophenylated wools. Among the various monomers studied, MMA was found to be the most active. A suitable kinetic scheme is proposed. From the activation energy data, average molecular weight, and spectral studies, the reactivity of -SH groups, and ...