M.B. Jackson

Synthesis of Cross-Linked Polyallylamines Which Are Resistant to Sulfite Attack

Abstract The effect of the type and amount of cross-linker, the monomer concentration, and the method of polymerization on the properties of some mine resins was studied. Resins were prepared by the free-radical initiated copolymerization of diallylamine or methyldiallylamine with a cross-linker such as 1,6-bis(N,N-dially1amino)hexane or triallylamine. Particular attention was given to controlling the factors responsible for the formation of pendant allyl groups in the resins since the presence of these groups is undesirable because they react with sulfite. Low monomer concentrations favored resins with low allyl content but the yield was also low. The best way of minimizing the number of pendant allyl groups is to use low levels of cross-linker. A resin with a very low pendant allyl group content, and therefore resistant to sulfite attack, was prepared from methyldiallylamine and 5 mol% 1,6-bis(N,N-dially1amino)hexane.

Polyampholytes for water treatment with magnetic particles

Abstract Amphoteric polymers which have cationic properties at acidic pH, but are neutral or anionic at alkaline pH, have been prepared and tested for water clarification and decolourization. The polymer is an adjunct to a magnetic iron oxide employed as the primary coagulant, which is recycled after alkaline treatment. A range of structures has been investigated, including copolymers of methacrylic acid with various quaternary ammonium monomers, terpolymers of these with methyl methacrylate as the third monomer, and polymers containing phenolic or amino acid moieties as well as quaternary ammonium sites. The last two groups of polymers were the most effective in enhancing water treatment performance, with concomitant facile regeneration behaviour.

Cyclopolymerization. XI. Polyelectrolytes and Polyampholytes from N-Alkyl-N, N-diallylamines and Methacrylamide

Abstract The preparation and properties of some poly[RN(CH2CH[dbnd]CH2)2hydrochlorides], where R may be methyl, n-propyl, n-hexyl, benzyl, and allyl, are discussed. Water-soluble polydiallyl-amine hydrochlorides have been prepared in high yields both by γ-irradiation and by chemical initiation. The polymers were characterized by solubility measurements, IR spectra, NMR spectra, and molecular weight determinations. Polydiallyl-amines as their free bases were found to gel both in solution and in the solid state; the factors influencing gelation were investigated. The polymerization of a mixture of methacrylamide and either methyl-or n-propyldiallylamine hydrochloride by chemical initiation and γ-irradiation in water, dioxane, and dimethylformamide was studied, and evidence is presented for and against the formation of a true copolymer. In all polymerizations, substantial quantities of either amine monomer or amine homopolymer were isolated. Although the amount of amine incorporated into the “copolymer” incr...

Reaction of Thiols and Bisulfite with the Pendant Allyl Groups in Polytriallylamine

Abstract The infrared spectrum of polytriallylamine prepared by the free-radical-initiated polymerization of triallylamine indicates the presence of a substantial amount of unsaturation. The usual quantitative methods of determining unsaturation (e. g., bromide/ bromate and mercuric acetate) cannot be used on polytriallylamine because of interference from the amino group. On the other hand, bisulfite was found to react rapidly and quantitatively with the pendant allyl groups of polytriallylamine. The reaction was studied over the pH range 4 to 10 and was fastest at pH 5.2. The reaction is a free-radical reaction which is catalyzed by metal ions and oxygen. The sulfonic acid groups which result from attack of bisulfite on the pendant allyl groups of polytriallylamine form strong zwitterion structures with the amine nitrogens. The addition of thiols is also a free-radical reaction. The reaction of HSCH2CH2OH, HSCH2CO2H, CH3SH, H2S, HSCH2CH2N(C2H5)2, CH5COSH, and C6H5SH with polytriallylamine was studied. Of...

The role of polyelectrolytes in a magnetic process for water clarification

Abstract Magnetite particles can be used to remove turbidity and colour from water supplies. The impurity-laden iron oxide particles are rapidly separated from the product water by magnetic techniques. The magnetite particles are then regenerated with alkali and reused. Turbidity removal by the process is greatly enhanced if a soluble cationic polyelectrolyte is employed in the clarification step. The present paper describes a range of commercially available and specially synthesized polyelectrolytes which have been tested to determine the polyelectrolyte structures required for the best performance in the process.

Preparation of Thermally Regenerable Ion-Exchange Resins by Polymerizing a Heterogeneous Mixture of Monomers

Abstract Crossinked resin beads containing regions of acidic and basic groups are the preferred structures for the efficient operation of a thermally regenerable ion-exchange process. In the present study they were prepared by polymerizing a heterogeneous mixture of acrylic esters and allylamines. Polymerization of unstable emulsions of acrylic esters and allylamines by heating the stirred emulsions gave very hard, strong resins which after hydrolysis had good acid, amine and thermally regenerable capacities. The thermally regenerable capacity depended very much on the nature of the acrylic ester and the allylamine. The order of increasing thermally regenerable capacity for the resins prepared is methyl acrylate (MA)/triallylamine (TAA), MA/diallylamine (DAA), MA/methyldiallylamine (MDAA) < ethyl acrylate (EA)/TAA, EA/DAA < EA/MDAA, butyl acrylate/MDAA. The dispersion of the unstable emulsions in a third phase resulted in immediate breakdown of the emulsion. The dispersion of partly prepolymerized emulsio...

Sulfur-containing resins from polyepichlorohydrin for mercury adsorption

Abstract The reaction of crosslinked polyepichlorohydrin (PECH) with either thioglycolic acid (TGA), KSH, NaSH or thiourea (TU) to give resins in which most of the pendent chloromethyl groups in the crosslinked PECH have been replaced by sulfur-containing groups is described. Despite the high sulfur content of the resins obtained by reaction with NaSH, no evidence for the formation of free thiol groups was found and their capacity for mercury(II) ions was low. On the other hand, the resins obtained by reaction with TGA had capacities for mercury(II) ions of greater than 2 mmol / g, while the best capacity for mercury of 4.2 mmol / g was found for a resin obtained by the TU reaction. The resins obtained by the TGA or TU reactions were difficult to regenerate, but could be completely regenerated with at least 1:1 HCl.

Amphoteric ion-exchange resins containing sulfonic acid groups from polyepichlorohydrin

Abstract The result of heating crosslinked polyepichlorohydrin (PECH) with sodium sulfite in water depends on which of two competing reactions is more important. The competing reactions are either chain cleavage, which produces water-soluble material, or nucleophilic displacement of the chloro groups to form sulfonic acid groups. With dithiol-crosslinked PECH chain cleavage is the predominant reaction to give water-soluble polymers. In contrast, the main reaction of diamine-crosslinked PECH with sodium sulfite is one which produces crosslinked resins containing sulfonic acid groups. Only a very small number of amino groups are needed in the crosslinked PECH to facilitate the latter reaction in which the covalently bound amino group acts as a covalently bound phase transfer catalyst. It is necessary for the phase transfer catalyst to be covalently bound because the use of phase transfer catalysts such as tetrabutylammonium iodide results in chain cleavage of dithiol-crosslinked PECH. Since some amino groups must be present in the crosslinked PECH to avoid chain cleavage, reaction with sulfite produces amphoteric resins. The formation of salt structures between the amino and sulfonic acids groups was demonstrated but it could not be determined whether they contributed to the degree of crosslinking.

Thermally regenerable ion-exchange resins. II the encapsulation of polyacid microparticles in a polyamine matrix

Abstract Thermally regenerable (TR) ion-exchange resins containing polyacrylic acid (PAA) microparticles encapsulated within a bis-diallylamino crosslinked polydiallylamine (PDAA) matrix were prepared with TR capacities of 1.2 to 1.3 meq/g. The effect of using various salts of the PAA including Co2+, Cr3+, Cu2+, Fe3+, Sn2+, Pb2+, Ca2+ and allylamine on the preparation and TR capacity of the resins was studied. The best capacity of 1.8 meq/g was obtained with the Ba2+ salt, but the resin lacked sufficient physical strength. Only relatively minor improvements in physical strength were achieved by an increase in the amount of the bis-diallylamino crosslinker from 5 to 15 mole % or by the use of the phosphate rather than the hydrochloride form of the diallylamine monomer. Post-crosslinking of the PDAA matrix with α,α′-dichloroxylene did not significantly improve the physical strength of the resin but reduced the resin swelling and therefore improved the TR capacity on a volume basis. The hypothesis that high TR capacities depend on the presence of low amounts of internal salt structures in the resin and therefore on low amounts of penetration of the amine monomers into the PAA or polyethyl acrylate (PEA) microparticles has been confirmed by the use of samples with different amounts of crosslinking. For example, the TR capacities for resins prepared from PAA with > 15% divinylbenzene (DVB), 10–15% DVB and 10% DVB as crosslinkers are 0.65, 1.23 and 1.31 meq/g, respectively. Similar, the TR capacities for resins prepared from PEA with > 15% DVB, 10–15% DVB and 2 1 2% DVB as crosslinkers are 1.55, 1.79 and 2.10 meq/g, respectively. The latter capacity of 2.1 meq/g for a resin prepared from the ester indicates that all the available sites in the resin are being used for salt adsorption.

The Reaction of Aliphatic Isocyanates with Some Compounds Which Contain an Active-Hydrogen

Abstract A study has been made of the kinetics and mechanism of the reactions of aliphatic isocyanates with several active-hydrogen compounds. The effect of hydrogen chloride on the reaction of aliphatic isocyanates with alcohols, water, ureas, and urethanes has been investigated. The significance of these results to the application of aliphatic isocyanate-terminated prepolymers to wool is discussed.