Star-shaped macromolecules with calixarene core and neutral amphiphilic block copolymer arms: New hosts for ions

Two neutral star-shaped polymers with calix[8]arene core and eight amphiphilic alkyloligoethyleneoxide arms have been synthesised using the arm-first approach. One of them has arms with oligoethylene oxide block attached to the calix[8]arene core, whereas the other one has arms where the oligoethylene oxide is the outer block. Both polymers are soluble in most common organic solvents and form true, i.e., molecularly dispersed solutions. In highly dilute aqueous solutions these polymers form loose multimolecular clusters, which do not disintegrate upon further dilution but break in a shear flow. Aggregation of these star polymers in water is investigated using light scattering and the structure of the aggregates is discussed. The ability of the stars to bind a series of metal ions and the effectiveness of these polymers as phase-transfer agents were investigated in respect to their molecular architecture. The performance of the star-shaped polymers was also compared to that of crown ethers.