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Séminaire Exceptionnel
"Matière et Systèmes Complexes"

                      

Mercredi 13 juin 2007 à 11h30
Bâtiment Condorcet, 6ème étage, salle 646 A.

Cosima Stubenrauch
(
UCD School of Chemical & Bioprocess Engineering)


Microemulsions as Templates for High Surface Area Polymers

Microemulsions are increasingly gaining importance as reaction media and templates since a great deal is known about how to tune the structure and the size of the domains. However, the 1:1 replication of the bicontinuous structure has not yet been achieved. The aim of this project is to develop a route for the synthesis of a bicontinuous solid sponge with a surface area as large as possible whose surface properties can be tuned. Potential applications of nanoporous, i.e. high surface area polymers are countless depending on the type of polymer and its functional entities. For example, semiconducting polymers could be used in photovoltaic cells, while polymers functionalized with biologically active entities might serve as biomimetic materials. Another promising area is the controlled release of drugs in pharmaceutical applications for which nowadays responsive macro- or microporous polymers are used. Having access to responsive nanoporous polymers with a high surface area would allow us to accelerate the response significantly.

Our approach to the synthesis of a bicontinuous high surface area polymer is to create a gel-like oil phase and to polymerize the aqueous phase hoping that the templating structure is not destroyed during the polymerisation process. To achieve this goal a suitable gelator had to be found. Then, the phase diagrams had to be studied after each compositional change, as the addition of gelators to the oil phase as well as of polymerisable monomers to the aqueous phase significantly affect the phase behavior of the microemulsion. In the presentation the general concept will be explained, the respective phase diagrams will be presented, and their use in the templating process will be described. Last but not least, the different length scales of a gel and a microemulsion, respectively, will be discussed and a structure for the gelled microemulsion will be proposed.