Photo-responsive supramolecular polymer bottlebrushes in solution

The synthesis of Azo-(U-PEO)2 was recently achieved by L. Harvey, a novel molecule containing both as a bis-urea and an azobenzene, imparting 1D self-assembly through cooperative hydrogen bonding and light responsiveness, respectively. Two poly-(ethylene oxide) arms (2000 g/mol per arm) are linked to the core, providing isolated polymer bottlebrushes in solution, that are soluble in both aqueous media and some organic solvents. Light scattering and cryo-TEM measurements show that this system self-assembles into long nanocylinders in water (several hundreds of nm long, Nagg = 900), and are disrupted upon irradiation. It is however mandatory to carry out SAXS measurements to study the polymer bottlebrush nanostructure in toluene as well as in mixtures of water/DMSO, probed in absolute scale of intensity over a wide q range (like D2AM-ESRF SAXS-detector at 2.9m: q=0.0025 to 0.15 Å-1 with WAXS overlap (det. 0.3m: q=0.08 to 1.4 Å-1 ) as already tested ; idem SWING-SOLEIL).