A reversible polymer (or supramolecular polymer) is defined as a mono-dimensional array of a large number of repeat units held together by reversible (non-covalent) interactions.
Unlike classical polymers, which rely on covalent bonds, reversible polymers have a length which is a function of temperature, concentration, polarity of the surrounding medium, … Thus, the properties of these compounds is also a function of external stimuli (such as temperature or mechanical stress), which makes it possible to obtain materials with unusual properties.
As an example, the following photograph shows a dilute (1 wt %) viscoelastic solution of a supramolecular polymer in xylene :
Within this context, we are interested in the following topics :
- synthesis of associative compounds,
- self-assembly by hydrogen bonding, hydrophobic interaction or pi-stacking, in solution (water, solvent) or in solid state,
- structural characterization of reversible polymers,
- solution properties of reversible polymers,
- solid state (glass, liquid crystal, crystal) properties of reversible polymers.
The diversity of our systems makes it possible to consider various applications, such as :
- rheology enhancers (personal care, inks, bitumen),
- self-healing materials,
- microporous membranes.
Recent achievements :
Drag reduction of hydrocarbon turbulent flow
In collaboration with Professor Edvaldo Sabadini (Campinas, Brasil), we have shown that the concept of supramolecular polymers can be fruitfully applied to the phenomenon of drag reduction in hydrocarbons. The added value of supramolecular polymers (compared to usual polymers) is the reversibility of their backbone, which suppresses chemical degradation due to the high shear forces (which typically occur in pipelines).
For more information, see : "Bis-urea based supramolecular polymer : The first self-assembled drag reducer for hydrocarbon solvents" E. Sabadini, K. R. Francisco, L. Bouteiller Langmuir 2010, 26, 1482-1486.
Improving bitumen mechanical properties
Low molar mass organogelators are known to turn liquids into thermoreversible gels, because they self-assemble into a fibrous network. In collaboration with Total company, we have extended this concept to bitumen, which is already solid-like on its own. We have shown that crystalline fibres of simple organic compounds are strong enough to improve the hardness and elastic modulus of bitumen at room temperature. Moreover, at high temperature, melting of the fibres improves processing.
For more information, see : "The weak help the strong : low molar mass organogelators harden bitumen" B. Isare, L. Petit, E. Bugnet, R. Vincent, L. Lapalu, P. Sautet, L. Bouteiller Langmuir 2009, 25, 8400-8403.