Title: Viscoelastic properties of associating polymers: When several dynamics are coming into play
Speaker: Prof. Evelyne Van Ruymbeke
Time: May 30, 10:00
Venue: Lecture Hall 324, Building 2, Wushan Science and Technology Park, Wushan Campus
[Abstract]
Understanding and tailoring the viscoelastic response of polymer melts or concentrated solutions from the knowledge of their molecular structure (architecture) represents a formidable challenge and remains an important field of soft matter research. In order to further study the dynamics of these samples, we have developed a general coarse-grained approach based on the tube model, that we are now using as a tool to investigate the viscoelastic properties of complex, entangled polymer architectures.
In the present work, we extend this approach to investigate the dynamics of reversible polymer networks, containing supramolecular junctions. The combination of stickers, exchangeable bonds and entanglements as topological constraints provides a large room to modulate the viscoelastic response of the networks. On one hand, the network elasticity depends on the density of the reversible junctions but also on the entanglements trapped within the network, the proportion of which depends on the topology of the building blocks. On the other hand, the relaxation time of the network depends on the cooperative effects of the stickers, dangling ends and entanglements, their corresponding lifetimes being a function of the sample composition.
Considering these different mechanisms, we show that it is possible to design very different transient networks but with exactly the same linear viscoelastic response at a specific temperature. But interestingly, these networks do not behave similarly at another temperature or under large deformation. This opens new possibilities to further control the networks dynamics, towards the design of samples with desired properties.
Announced by the School of Molecular Science and Engineering
