Properties of various thermoassociating polymers: pharmaceutical and cosmetic applications

This paper describes the main results obtained in our group on three thermoassociating polymers with interesting applications in the pharmaceutical and cosmetic fields. These three polymers are based on the poloxamer structure. The poloxamer macromolecules per se have interesting thermoassociating properties in aqueous solutions but they can also be integrated as sub-units in the design of more complex molecular architectures such as grafted poloxamers. The thermoassociating properties and the sol–gel transition of these three different systems were investigated in aqueous solutions mainly by rheology. The poloxamer gels were then assessed as in situ generated implants for the controlled release of vancomycin. They were also incorporated in more complex formulations containing liposomes to protect unstable actives such as antisense oligonucleotides. As regards the grafted poloxamers, a lower polymer concentration was required to induce the gelation. Moreover, the viscosity of these hydrogels remains high enough under shear rates that correspond to a topical application. These properties make them suitable for the formulation of multiple emulsions that can release an entrapped active molecule under shear when the formulation is topically applied.