Synthesis and Properties of Hydrophilic Polymers I. Preparation and Metal Complexation of Poly(4-vinylpyridine-co-N-allylthiourea)

Abstract

ABSTRACT:Copolymers of 4-vinylpyridine and N-allylthiourea with different mole fractions were synthesized by radical copolymerization in bulk. The AIBN-initiated copolymerization was found to strongly favor the 4-vinylpyridine monomer in the copolymer composition. This was confirmed by viscosity measurements with a linear relationship between the reduced viscosity and the comonomer content. Interactions and complexation of the water-soluble copolymers with nine metal ions were investigated in aqueous solution by means of a membrane filtration technique. This technique is designed to remove and separate metal ions from diluted solutions by binding them to soluble polymers. The effects of several parameters, such as copolymer composition, filtration factor, and pH were studied as a function of the interaction of the copolymers with metal ions. A strong selectivity for copper(Il) was found which was pronounced at a monomer ratio of I: 2 (4-vinylpyridine: N-allylthiourea). Also a partial interaction of iron(III) and the copolymer (2: 1) was observed at pH 3 which was strongly pH-dependent.KEY WORDS N-Allylthiourea / Aqueous Solution / Copolymerization / Metal Complexation / 4-Vinylpyridine / Hydrophilic polymers represent an important class of polymeric materials due to their salient properties and their great spectrum of practical applications. A number of different polymer structures can provide the desired properties of materials with respect to the application purpose. 1 · 2 A hydrophilic character of the polymer and compatibility with many polar solvents are especially suitable that can be attained by introducing solubilizing constitutional repeat units by copolymerization. Among these, pyridine groups play an essential role by reason of the chemical functionality of such materials as well as the commercial availability of the corresponding monomers. affinity of pyridines as monomeric and polymeric derivatives is well-known. 4 Poly(4-vinylpyridine)s have been also investigated in terms of their metal complexing behavior. 5 • 6 Nishide and Tsuchida investigated the selective adsorption of metal ions on resins based on 4-vinylpyridine. 7 In that study, fixed coordination sites were produced using a template technique with 1,4-bromobutane as crosslinking agent. Additionally, another study showed that the incorporation of pyridine moieties has an enhancing effect on the stability of metal complexes. 8 However, very few studies focus on the properties of poly(4-vinylpyridine)s and copolymers in aqueous solution. 2 • 9 Fundamental studies on the homopolymerization and copolymerization of the 4-vinylpyridine monomer have been the subject of a number of studies. 3 The metal binding Previously, N-allylthiourea copolymers with acrylic acid were reported and studied as macromolecular complexing agents. 10 In more detail, the influence of the thiourea ligand on 115

Removal of Metal Ions from Aqueous Solutions by Complexation –Ultrafiltration Hybrid Process: A Bibliographical Overview

“…Besides, the process finds an important area of applications in the removal of particularly toxic metal species as lead which is one of the most dangerous metal species contaminants, cadmium [81,82], one of the most toxic heavy metals with its negative effect on the environment where it accumulates throughout all the food chain [83] and mercury which is collectively known as one of the most toxic metal species pollutants [66,[84][85][86]. Numerous other metal species have found in complexation -ultrafiltration a relevant alternative to classical processes of separation [87][88][89][90][91], the above cited research studies are some samples of the rich fields of application of this promising hybrid process.…”

Synthesis and properties of hydrophilic polymers, 5. Viscosimetric study on poly(acrylamide-co-4-vinylpyridine) and its interaction with metal ions in aqueous solution

“…Also, the complexing properties of the acrylamide function 22) and particularly of polymer 3 23) have been studied. Previous studies included also other copolymers of 4-vinylpyridine 24) . At a constant concentration of 1, 2, and 3, an increase in the amount of copper(II) caused a decrease in the viscosity (Fig.…”

Study of the Liquid-Phase Hydrogenation of Benzene in the Presence of Metal-Polymer Complexes Based on Polyvinylpyridines

“…Attempts to eliminate the shortcomings of a homogeneous catalyst led to the creation of complexes containing organic polymers as microligands. In this case, the polymers act mainly as a heterogenizing substrate [8][9][10][11][12][13][14][15][16][17][18][19].…”