Hexameric cycles from hydrogen-bonded ureido-pyrimidinones

Supramol. polymers form a new class of polymers in which the reversibility of the non-covalent bonds between the monomers gives rise to interesting material properties. Ureido-pyrimidinone mols. strongly dimerize via quadruple hydrogen bonds and bi-functional derivs. form polymers or cyclic structures depending on the pre-organization of the linker and external conditions such as concn. and temp. Bi-functional ureido-pyrimidinone mols. with a meta-phenylene linker aggregate into hexameric cycles, due to pre-organization of the phenylene linker. SANS, viscosity and NMR-diffusion measurements showed that the hexameric cycles self-assemble into cylindrical aggregates, with solvent, concn. and temp. dependent length. These cylindrical aggregates may be used as scaffolds for thermoplastic elastomers, in which the cylinders form the hard-block and the polymer the soft-block. [on SciFinder (R)]