The University of Navarra has chosen Wyatt Technology’s DynaPro dynamic light scattering instrument (DLS) to characterise phase transitions and structures in micellar polymeric systems. With ability to measure small volumes of dilute protein samples, a key strength of DLS technology is its capability of detecting aggregation early due to temperature effects, pH, salinity concentration or composition. For the application at the University of Navarra, the system was used for the micellisation of a Pluronic polymeric surfactant with temperature. These amphiphiles are low molecular weight linear triblock copolymers of polyethylene oxide (PEO) and polypropylene oxide (PPO), with structures PEO-PPO-PEO, in which the hydrophilic character is controlled according to the PEO block length. Pluronic F108 was chosen which was a central block of 52 PO monomers and PEO wings of 131 EO.
The results demonstrated that, at a low temperature, the polymeric surfactant exists in monomer form. The onset of micellisation was perceived both in the intensity and in the hydrodynamic radius obtained by the cumulants method of the company’s DYNAMICS software. A copy of an application note, entitled ‘Critical Micellization Temperature (CMT) of Block Copolymers of PEO and PPO’, is available to download at www.wyatt.com