Synthesis and metal cation separation of chelating polymers containing crown ether units
Each of the three parts of this dissertation research involves organic synthesis, monomer polymerization and polymer characterization, analytical chemistry and host-guest chemistry. The overall goal is to synthesize several different types of novel monomers and polymers which contain crown ether units and then study their complexation behavior with metal cations by sorption measurement, liquid-liquid or liquid-solid extraction or membrane transport techniques. The types of crown ether polymers described in the dissertation include formaldehyde condensation crosslinked resins, linear styryl-type polymers and polyamides. In the first part of the research, the influence of adding alkali-metal cations in the formaldehyde polymerization of dibenzo polyethers was investigated. It was found that cation complexation of the dibenzocrown ether monomer diminished the efficiency of the polymerization process, neutral crown ether resins and crown ether carboxylic acid resins with different levels of crosslinking were also prepared and their alkali-metal ion sorption efficiency and selectivity have been studied. Lastly, formaldehyde dibenzo- 18-crown-6 resins with varying levels of phosphonic monoacid and diacid group substitution were also prepared. The effect of the identity and level of the phosphonic acid groups on alkali-metal cation sorption by the resins was investigated. The second part of the research in the dissertation was the synthesis of some novel linear styryl-type crown ether polymers, some of which include ion-exchange sites in the polymer structure. The influence on metal picrate extractions for variation of the crown ether substituent group, side arm and spacer group between crown ether unit and polymer backbone in the polymers was studied. Factors, including the introduction of crown ether units and preorganization of the ion-exchange site relative to crown ether cavity, were also examined with regard to their effects on the metal cation sorption behavior of the ion-exchange crown ether polymers. The final part of the research in the dissertation involves the synthesis and characterization of a number of novel crown ether polyamide esters and acids. The crown ether units were incorporated within the polymer backbones. Some of the prepared polyamides could be cast to form mechanically strong membranes. This feature is crucial for potential applications in industry. Alkali-metal cation sorption by the crown ether polyamide acids and transport of alkali-metal cations across crown ether polyamide carboxylic acid membranes were investigated.