Thermodynamic study of crown ether-lithium/magnesium complexes based on benz-1,4-dioxane and its homologues.

The synthesis and characterization of benz-1,4-dioxane crown ethers (CEs) and some of its homologues are described and analyzed. The effect of added C-atom within the CE ring (increasing the hydrophobicity of the CE ring by increasing the number of CH-units) on the Li and Mg complexation within a liquid-liquid extraction (LLE) is investigated and thermodynamically analyzed. The complex stability constant , the change of entropy Δ and enthalpy Δ, and the Gibbs energy Δ are determined.

Improved alkali metal ion capturing utilizing crown ether-based diblock copolymers in a sandwich-type complexation.

The compexation behavior of metals with free crown ethers (CE) and diblock copolymer-based CE is investigated. The latter shows at least 10 000 times stronger complexation than free CEs. On this basis, a highly stable CE complex within the polymer for efficient extraction of metal ions from low concentrations, lithium in seawater, is presented.

Synthesis of Poly(methacrylic acid)--Polystyrene Diblock Copolymers at High Solid Contents via RAFT Emulsion Polymerization.

The combination of polymerization-induced self-assembly (PISA) and reversible-addition fragmentation chain transfer (RAFT) emulsion polymerization offers a powerful technique to synthesize diblock copolymers and polymeric nanoparticles in a controlled manner. The RAFT emulsion diblock copolymerization of styrene and methacrylic acid (MAA) by using a trithiocarbonate as surfactant and RAFT agent was investigated. The Z-group of the RAFT agent was modified with a propyl-, butyl- and dodecyl- sidechain, increasing the hydrophobicity of the RAFT agent to offer well-controlled polymerization of poly(methacrylic acid)--polystyrene (PMAA--PS) diblock copolymers at high solid contents between 30-50 wt% in water.

A Highly Selective Polymer Material using Benzo-9-Crown-3 for the Extraction of Lithium in Presence of Other Interfering Alkali Metal Ions.

The recovery of lithium from global water resources continues to be challenging due to interfering metal ions with similar solution properties. Hence, a lithium-selective diblock copolymer system containing crown ethers (CEs) is developed. A polystyrene-block-poly(methacrylic acid) diblock copolymer is synthesized first via a one-pot solution-emulsion reversible addition-fragmentation chain transfer polymerization.