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Séminaire SIMM - Oscar Lopez-Pamies (Illinois)
29 novembre 2023Mercredi 13 décembre 2023 de 11h00 à 12h30 - HolweckOscar Lopez-Pamies (University of Illinois Urbana-Champaign)
Towards a Complete Theory of Fracture : The Special Case of RubberIn this talk, I will present a macroscopic (continuum) theory, alongside its numerical implementation, aimed at describing and predicting when and how fracture nucleates and propagates in a body made of rubber that is subjected to arbitrary quasistatic loading conditions.
I will begin by summarizing the slew of existing experimental observations on nucleation and propagation of fracture in rubber that have been generated ever since vulcanized rubber was invented by Charles Goodyear in the 1840s. The observations will reveal that there are three basic ingredients that any attempt at a complete macroscopic theory of fracture ought to account for : i) the elasticity of the rubber, ii) its strength at large, and iii) its fracture energy.
Having pinpointed the basic ingredients required for a complete theory, I will then present one such theory, regularized, of phase-field type. The theory can be viewed as a natural generalization of the phase-field approximation of the celebrated variational theory of brittle fracture of Francfort and Marigo (1998) — which is nothing more than the mathematical statement of Griffith's competition of bulk and fracture energies — to account for the material strength at large.
In the latter part of the presentation, I will illustrate the descriptive and predictive capabilities of the theory via simulations of several famous experiments, including poker-chip experiments in both natural and synthetic rubber.
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SEMINAIRE SIMM/C3M - Martina Stenzel (UNSW, CAMD, Sydney)
29 novembre 2023Vendredi 8 décembre 2023 de 11h00 à 12h30 - HolweckMartina Stenzel (UNSW, CAMD, Sydney)
Sugar coated nanoparticles big and small – how polymer science can enhance nanomedicine
Nanomedicine is a field of interesting interest. Rapid development of nanotechnology has allowed the incorporation of multiple therapeutic, sensing and targeting agents into nanoparticles. Most commercially available nanoparticles use poly(ethylene glycol) PEG as hydrophilic coatings. However, materials based on sugars such as polymers with pendant carbohydrates, coined glycopolymers, are attractive alternatives. Carbohydrates play a pivotal role in many biological processes and by using glycopolymers we mimic naturally occurring events. The presence of carbohydrates on the surface on nanoparticles can therefore help the uptake of these nanoparticles into mammalian cells. In this presentation, we look into a range of nanoparticles based on glycopolymers, ranging from ultrasmall nanometer sizes nanoparticles to large micron-sized 2D platelets and discuss how these particles can be used in drug delivery applications. A focus will be how small molecules such as drugs can be loaded and how the drugs change the properties of polymers, and thus their biological activity.