Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 8: Glasses I (with CPP, talks by CPP)

DY 8.1: Hauptvortrag

Montag, 26. März 2012, 15:00–15:30, C 243

Glass transition by molecular network topology freezing and discovery of vitrimers — •Ludwik Leibler, Damien Montarnal, Mathieu Capelot, and François Tournilhac — Matière Molle et Chimie, ESPCI, 10, rue Vauquelin, 75005 Paris, France

We will discuss a concept and practical realizations of a glass transition by reversible topology freezing of a molecular network. Permanently cross-linked materials, like thermosets or rubbers, have outstanding mechanical properties and solvent resistance, but they cannot be processed and reshaped once synthesized. Non-cross-linked polymers and those with reversible cross-links are processable, but they are soluble. We design epoxy networks able to rearrange their topology by exchange reactions without depolymerization and show that they are insoluble and processable. Unlike organic compounds and polymers whose viscosity varies abruptly near glass transition, these networks, vitrimers, show Arrhenius-like gradual viscosity variations just like vitreous silica. Like silica, the vitrimers can be wrought and welded to make complex objects by local heating without the use of molds. The concept of a glass, made by reversible topology freezing in epoxy networks can be readily scaled up for applications and generalized to other chemistries.