Stimuli responsive graft polysiloxanes

International audience; Stimuli sensitive amphiphilic polymers based on partially substituted graft polysiloxanes were obtained and characterized. The polymers were synthesized in a two-step reaction, starting from a polysiloxane with chlorobenzile groups in the side chain. In the first step, the polysiloxane was modified with dinitro- or azo-aromatic group and, in the second step, the unreacted chlorobenzile groups were grafted with thermo-sensitiue poly (N, N-dimethylacrylamide (PDMA) side chains in a Single Electron Transfer-Living Radical Polymerization (SET-LRP) reaction. The polymer structures and their properties were investigated by 1H-NMR spectroscopy, DSC, fluorescence and UV-VIS spectroscopy and rheology. Because of the amphiphilic character, these polymers are self-assembling in aqueous solution in a core-shell micelles, the critical concentration of the aggregation value being in the 10-1 range. The thermo-sensitive character, the lower critical solution temperature (LCST) and the conformational changes of the side-chains are evidenced by rheological temperature sweep tests.