Polymer-Supported 14-Crown-4 and Bifunctional Resins for Selective Metal Ion Complexation: Synthesis and Characterization

Polymer-supported 14-crown-4 and bifunctional resins containing amine and phosphonate ester ligands were synthesized and characterized. Complexation studies were performed to evaluate the metal ion selectivity of the resins.

The immobilization of 14-crown-4 onto crosslinked polymer supports for the complexation of Li(l) from aqueous solutions was studied. M any methods were attempted, but etherification of the hydroxymethyl form of 14-crown-4 was found to be the most successful. The polymers examined were poly(vinylbenzyl chloride), poly(vinylbenzyl chloride)-co-acrylamide and poly(glycidyl methacrylate). The amount of Li(l) complexed by the crown ether supported polymers was affected by the polarity (i.e., hydrophilicity) of the polymer matrix. The greater the hydrophilicity of the polymer matrix, the greater the amount of Li(l) complexed. The degree of functionalization of the crown ether was found to be affected by the resin porosity and the reaction conditions. Of the resins studied, the poly(glycidyl methacrylate) demonstrated the best performance.

Bifunctional resins containing dialkyl phosphonate esters and dialkylamines with groups corresponding to the phosphonate esters were prepared. Preliminary complexation experiments were performed using a bifunctional resin consisting of the methyl forms of the phosphonate and amine. For comparison, monofunctional analogues of the bifunctional resin and a dimethylamine-contacted fully functionalized dimethyl phosphonate ester were also prepared. Complexation results indicated that hydrolysis occurred with the dimethylamine-contacted phosphonate ester resin based on increased metal ion sorption capacities. Analysis for acid capacity and by FTIR demonstrated that a low level of hydrolysis occurred. Hydrolysis was also demonstrated with several other amines used for example, ethylenediamine and piperidine. Upon characterization of the butyl and ethyl analogues of the amine-contacted fully functionalized phosphonate ester resin, it was seen that hydrolysis did not occur. In complexation studies at the butyl/butyl form of the bifunctional resin demonstrated increased metal ion sorption capacity, in comparison to the other butyl resins synthesized however, the ethyl/ethyl form of the bifunctional resin did not.