Linear and nonlinear shear rheology of linear metallo-supramolecular polymers

Details

Supervisors

Van Ruymbeke, Evelyne

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

Supramolecular polymers are a promising class of polymers with highly tunable and dynamic properties, which makes them a great candidate for the development of new, adaptive and sustainable materials. The present master thesis investigates entangled metallo-supramolecular assemblies from a rheological point of view. All samples were based on the same entangled polymer, the poly(n-butyl acrylate) end-terminated by tridentate terpyridine ligands (PnBAtpy2), to which different densities of copper and/or zinc ions were added. The objective was to analyze these samples’ rheological behavior in both linear and nonlinear regimes, including the influence of ion nature, ion density and temperature on their dynamics. For the linear modeling of PnBAtpy2, several approaches have been proposed and tested to describe the linear viscoelastic data of the samples. The assumption that it is the mono-complexes which phase separate gave us consistent results. The model allows to confirm the presence of aggregates in samples containing copper ions as well as in the sample containing 2.5eq. zinc ions. For the nonlinear analysis of the metallo-supramolecular polymers’ viscoelasticity under larger shear flows, we measured and compared the transient viscosity of the different samples. The main observation was an unexpected double overshoot, a phenomenon which still needs further investigation, but to which we can already impute the presence of aggregates.