Phosphonic acid functionalized monomers

In addition, there are several investigations on proton exchange polymers, whose phosphonic acid sites are linked to aromatic ring directly or by means of alkylene spacers. These polymers can be prepared by polycondensation of phosphonic acid functionalized monomers or phosphorylation of existing aromatic condensation polymers. There are several methods reported for the preparation of arene phosphonates from aryl bromides [38-40]. The classical Arbuzow reaction [41,42] is commoifly used, in which triethylphos-phite and nickel dichloride are employed as catalysts. The reaction often requires harsh conditions (160 °C) and suffers from low yields. Alternative paUadiiun-catalyzed reaction [43-45] useful for phosphonation proceeds more smoothly. 

In general, few articles on the polycondensation of phosphonic acid functionalized monomers can be found. 

Generally, preparation of phosphonic acid functionalized monomers and their polymerization are problematic, because of the strong aggregation and condensation of phosphonic acid imits which result in poor yields [7,33,56-58]. Consequently, a more attractive strategy is to phospho-rylate existing polymers [59]. 

FIG. 2.21 Synthesis of new aromatic perfluorovinyl ether monomers containing phosphonic acid functionality [99]. 

Various strategies for the syntheses of either aliphatic or aromatic functional fluorinated monomers have been proposed in the hterature. Because of their costs, they have been involved in copolymerization with fluoroalkenes, and although a lack of basic research is noted (e.g., no assessment of the reactivity ratios), many apphed investigations have been developed. In fact, most companies producing fluorinated monomers and derivatives have solved the challenge to prepare fluorocopolymers bearing sulfonic acid side groups. Nevertheless, quite a few studies concern phosphonic acid function. Compared with direct copolymerization, the alternative to prepare fluorofunctional copolymers by chemical modification of polymers is often employed. 

Souzy, R., Ameduri, B., Boutevin, B., Virieux, D. (2004) Synthesis of new aromatic perfluorovinyl ether monomers containing phosphonic acid functionality. Journal of Fluorine Chemistry, 125, 1317-1324. 

Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. This research has been conducted in an effort to functionalize a polymer with a variety of different reactive sites for use in membrane applications. These membranes are to be used for the specific separation and removal of metal ions of interest. A porous support was used to obtain membranes of a specified thickness with the desired mechanical stability. The monomer employed in this study was vinylbenzyl chloride, and it was lightly crosslinked with divinylbenzene in a photopolymerization. Specific ligands incorporated into the membrane film include dimethyl phosphonate esters, isopropyl phosphonate esters, phosphonic acid, and triethyl ammonium chloride groups. Most of the functionalization reactions were conducted with the solid membrane and liquid reactants, however, the vinylbenzyl chloride monomer was transformed to vinylbenzyl triethyl ammonium chloride prior to polymerization in some cases. The reaction conditions and analysis tools for uniformly derivatizing the crosslinked vinylbenzyl chloride / divinyl benzene films are presented in detail. 

Ester hydrolysis is most conveniently used because (1) its reaction mechanism is well established, and (2) both substrate and transition state analogs are easy to obtain. In Fig. 8.8b, phosphonic acid (2) is used as a transition state analog of the hydrolysis of substrate 3 [26]. A vinyl monomer of amidine 1 is chosen as a functional monomer because it readily forms stable complexes with the carboxylic acid ester and the phosphonic acid monoester. The imprinted polymers are synthesized in THF from 1 (the monomer), 2 (the template), and ethylene glycol dimethacrylate (the cross-linker) by using AIBN as the radical initiator. 

The invention of Heath et al. relates to novel phosphonate allyl monomers, made from reaction of an unsaturated oxirane with amine- or hy-drojyl-functionalized phosphonic acids (Scheme 3.21). These monomers were copolymerized with other unsaturated species (acrylic acid, maleic acid, acrylamide, or monomer derivatives of sulfonic acid, etc), yielding phosphonate polymers or oligomers. Phosphorus-containing monomers were incorporated at a ratio of 0.1-30% and polymerized in aqueous media. The final polymers had a molecular weight of 800-30 000 g mol . With their phosphonic acids groups (free acid or salts forms), they are of particular use as oilfield scale inhibitors. 

Phosphonate monomers of type 1 were made from the reaction of allyl glycidyl ether with hydroxy-functionalized phosphonic acid. To obtain azo-phosphonated products (type 2), multicomponent reactions (amine-, aldehyde/ketone-, or phosphorus-containing compounds) such as the Kabachnick-Fields," Mannich," or Moedritzer ° reactions, were used. These reactions generated in a selective way the a-aminoallq lphosphonate products. 

Acidic monomers could be phosphates as well as carboxylic, sulfonic, or phosphonic acids. Some examples of carboxylic acid monomethactylates are 4-(2-methactyloyloxyethyl)trimellitic acid (4-MET) and 11-methactyloyloxy-1,1-undecanedicarboxylic acid (MAC-10). Among the functionalized monomers, free-radically polymerizable phosphonic acids (PAs) and dihydrogen phosphates (DHPs) have found wide and intensive applications as adhesive components in enamel/dentin adhesives. In this chapter, a review of the various PAs and DHPs prepared for application in dental adhesives is provided. 

In addition to functionalization of polyanilines with sulfonic and carboxylic acids, the corresponding phosphonic acid derivatives have been prepared, o-Aminobenzylphosphonic acid was prepared as shown in Figure 20.54 [42,43]. Oxidative coupling of the above monomer in an acidic medium yielded poly(o-aminobenzylphosphonic acid) (Figure 20.55). Spectroscopic analysis was consistent with head-to-tail oxidative coupling through the /Jara-position. The as-prepared polymer was in its emeraldine oxidation state in which 43% of the N-atoms were protonated by the pendent acid. This polymer was insoluble in both non-aqueous solvents and aqueous acidic solutions. 

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