Self-Assembly and Critical Solubility Temperature of Supramolecular Polystyrene Bottle-Brushes in Cyclohexane

Abstract

The formation of polystyrene (PS) supramolecular bottle-brushes by self-assembly in cyclohexane of hydrogen-bonding tris­(urea) units decorated by PS chains was investigated using light and neutron scattering. Atom transfer radical polymerization (ATRP) was used to control the length of the PS side-chains and allowed the straightforward synthesis of the targeted tris­(urea)­s. It was shown that their extent of self-assembly strongly depended on the degree of polymerization and chemical nature of the polymer side chains, in contrast with what was previously observed with cyclic oligopeptides, another type of self-assembling units. With sufficiently short PS side-chains, anisotropic supramolecular bottle-brushes could be obtained. Their critical solubility temperature, <i>T</i>_c, was measured in cyclohexane, proving experimentally for the first time that densely grafted PS bottle-brushes exhibit a much lower <i>T</i>_c than linear PS or even star-shaped PS of similar molecular weight