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College Park, Maryland      June 6 - 10 , 2004

WP52: Effects of Temperature and Salts on the Micelle Structure of Triblock Copolymer P84 in Aqueous Solutions

L. Guo, P. Thiyagarajan (Intense Pulsed Neutron Source, Argonne National Lab)

We investigated the phase behavior of aqueous solutions of a triblock copolymer Pluronic P84 (EO19PO43EO19) at different copolymer and sodium carbonate concentrations and temperatures by using small angle neutron scattering (SANS). We obtained information on the shape and size of Pluronic P84 micelles, aggregation number and the volume fraction of the micelles. The results show that temperature and carbonate ion concentration have strong influence on the phase behavior of the triblock copolymer. The micelle aggregation number and size increase with polymer and carbonate ion concentrations as well as temperature. The CMT decreases with increasing temperature and carbonate ion concentration. At high temperatures and carbonate ion concentrations, spherical to cylindrical micelle transformation occurs. Phase separation is observed at sufficiently high temperatures and carbonate ion concentrations.

This work benefited from the use of the Intense Pulsed Neutron Source at Argonne National Laboratory funded by the Office of BES, US DOE under the contract # W-31-109-ENG-38. We thank Denis Wozniak at IPNS for his assistance with the SANS experiments.

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