Dynamic Light Scattering for Critical Micellisation of Polymeric Systems with Temperature

Wyatt Technology Corporation has been chosen by the University of Navarra for its instruments to characterise phase transitions and structures in micellar polymeric systems. Wyatt Technology’s dynamic light scattering instrument, the DynaPro, facilitated the detection of aggregation in early stages of micellisation of pluronic polymeric surfactant due to temperature effects, pH, salinity concentration and composition. The DynaPro from Wyatt Technology offers scientists the ability to measure small volumes of dilute protein samples. These novel dynamic light scattering (DLS) instruments have been indispensable tools for scientists examining protein structure. One of the key strengths of DLS technology is its capability of detecting aggregation early due to temperature effects, pH, salinity concentration or composition. The unique temperature control capability of the DynaPro allows for accelerated stability, thermal melting and temperature studies of multiple samples to be performed in parallel and with improved response time. The DynaPro achieves simultaneous and rapid evaluation of the total scattering intensity and the hydrodynamic radii spectrum in micellar polymeric systems with temperature in a non-invasive fashion.

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 demonstrate that, at a low temperature, the polymeric surfactant exists in monomer form. The onset of micellisation can be easily perceived both in the intensity and in the hydrodynamic radius obtained by the cumulants method of Wyatt Technology’s DYNAMICS software. The regularisation analysis of DYNAMICS provides the size spectrum of the sample and reveals a new peak corresponding to the micelles.