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Updated: May 11, 2026
Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Photo-responsive supramolecular polymer bottle-brushes: The key role of the solvent on self-assembly and
Luke Harvey1, Ralf Schweins2, Isabelle Morfin3
1Institut des Molécules et Matériaux du Mans (IMMM), UMR 6283 CNRS, Le Mans Université, 72085 Le Mans Cedex 9, France.
Hypothesis:
Supramolecular polymer bottlebrushes (SPBs) consist in the 1D self-assembly of building blocks composed of a self-assembling core with pendant polymer arms. Kinetic hurdles often hinder their stimuli-responsiveness in solution. Changing the nature of the solvent should alleviate these hurdles by modulating the self-association strength, leading to stimuli-responsive SPBs.
Experiments:
The SPBs were formed, in various solvents, by hydrogen bond-driven self-assembly of an azobenzene-bisurea decorated with poly(ethylene oxide) polymer arms. The photo-isomerization of the azobenzene unit was studied by UV/visible spectroscopy and proton NMR spectroscopy, whereas the consequences on supramolecular self-assembly were studied by small angle neutron and X-ray scattering.
Findings:
In water, the assembly was previously shown to be driven by both hydrogen-bonds and strong hydrophobic effects, the latter rendering the system kinetically frozen and the disassembly irreversible. Here we show that in organic solvents such as toluene or chloroform, reversible light-responsive dissociation is achieved. Solvophobic effects in these solvents are expected to be much weaker than in water, which probably allows reversibility of the light-response in the former solvents. The key role of the solvent on the reversibility of the process opens up new perspectives for the design of stimuli-responsive SPBs and their applications in various fields.
