Speaker: Prof. Laurence Brassart

Abstract

Understanding the relationships between the structure of polymer networks and their mechanical properties remains a long-standing challenge in polymer physics. In recent years, a new paradigm for network formation has emerged, whereby near-ideal hydrogels are produced by the cross-coupling of branched macromolecules with well-defined chain length. Such near-ideal networks constitute an excellent model system to revisit this question, as well as a promising platformfor the design of new materials with tuneable properties. In this work, we systematically investigate the relative contributions of various network parameters (chain length, crosslink coordination, second-order loops) to the elasticity of near-ideal polymer networks using a computational random network model. Numerical results are compared to classical estimates of rubber elasticity theory. Our results highlight the role of the chain pre-stretch on the mechanical response, as well as the importance of topological defects on the elastic properties. We also compare our results to experimental data for near-ideal tetra-arm PEG hydrogels.

Biography

Laurence Brassart is an Associate Professor in the Department of Engineering Science of the University of Oxford, and a Tutorial Fellow at Christ Church College. She graduated with a Diploma in Mechanical Engineering from the Université catholique de Louvain in 2007, and with a PhD in Engineering Sciences from the same university in 2011. She then successively held postdoctoral positions at Harvard University (Fellow of the Belgian American Educational Foundation) and the Université catholique de Louvain (Chargé de Recherche FNRS). From 2015 to 2019, she was a Senior Lecturer in the Department of Materials Science and Engineering at Monash University (Melbourne), before joining Oxford University in August 2019. Her research focuses on the development of original constitutive models and micromechanical approaches for a broad range of materials. Her current research focuses on modelling multiphysics couplings in soft materials and polymers.