Partners and International Organizations
(English)
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A, B, CZ, DK, F, D, GR, H, IRL, I, NL, N, PL, P, SI, SK, E, S, CH, GB
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Abstract
(English)
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This project has been proposed to study the microscopic structure and dynamics of biopolymer systems undergoing a sol-gel transition and relate them to their macroscopic viscoelastic properties. In the first year the system under investigation was milk (fat-free and fat-containing milk) and the techniques used for its characterization were Diffusing Wave Spectroscopy (DWS), Dynamic and Static Light Scattering (DLS, SLS) and classical rheology. We focused in particular on the characterization of the microscopic structural and dynamic properties of the aggregating suspensions and gels using a modern multiple light scattering technique - Diffusing Wave Spectroscopy (DWS) - which is an extension of Dynamic Light Scattering (DLS) to turbid media. We were able to demonstrate that one can link the macroscopic properties of the sol-gel transition as well as of the final gels, e.g. their viscoelastic behavior (obtained from classical rheology), to their microstructural properties. In the second year we have focused on the use of colloidal tracer particles in order to apply DWS and optical microrheology as a non-invasive and in-situ tool also for transparent systems such as biopolymer solutions and gels. We have been able to demonstrate that with such an approach we can obtain rheological data with an unprecedented range of frequencies. This project has thus helped in preparing the ground to use DWS-based microrheology in complex gel systems.
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